44 lines
1.3 KiB
C
44 lines
1.3 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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// Define the length of the serial number
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#define SERIAL_LENGTH 5
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int verify_key(char *serial) {
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// Allocate a buffer to store the derived key (5 capital letters + null byte)
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char derived[SERIAL_LENGTH + 1] = {0};
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// Derive the key from the serial by iterating over the serial
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// and subtracting 2 times the current index from each character
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for(int i = 0; i < SERIAL_LENGTH; i++) {
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derived[i] = serial[i] - 2 * i;
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}
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// Compare the derived key with the expected key "MMNNQ"
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if(strcmp(derived, "MMNNQ") == 0)
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return 1; // Return 1 if the keys match
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return 0; // Return 0 if the keys do not match
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}
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int main(int argc, char **argv) {
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// Buffer to store the user input (5 capital letters + null byte)
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char serial[SERIAL_LENGTH + 1] = {0};
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// Read the serial number from the user and store it in the serial buffer
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printf("Enter serial (5 capital letters):\n");
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scanf("%5s", serial);
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// Verify the serial number
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if(verify_key(serial)) {
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// Print this message if the serial is correct
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printf("Key is valid! Whoop whoop :)\n");
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} else {
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// Print this message if the serial is not correct
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printf("Key is not valid :(\n");
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}
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// End the program without errors
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return 0;
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}
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