135 lines
3.6 KiB
C
135 lines
3.6 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdbool.h>
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#include <ctype.h>
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#include <time.h>
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char *find_little_endian(const char *word)
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{
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size_t word_len = strlen(word);
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char *little_endian = (char *)malloc((2 * word_len + 1) * sizeof(char));
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for (size_t i = word_len; i-- > 0;)
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{
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snprintf(&little_endian[(word_len - 1 - i) * 2], 3, "%02X", (unsigned char)word[i]);
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}
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little_endian[2 * word_len] = '\0';
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return little_endian;
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}
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char *find_big_endian(const char *word)
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{
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size_t length = strlen(word);
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char *big_endian = (char *)malloc((2 * length + 1) * sizeof(char));
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for (size_t i = 0; i < length; i++)
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{
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snprintf(&big_endian[i * 2], 3, "%02X", (unsigned char)word[i]);
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}
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big_endian[2 * length] = '\0';
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return big_endian;
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}
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char *generate_random_word()
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{
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printf("Welcome to the Endian CTF!\n");
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printf("You need to find both the little endian and big endian representations of a word.\n");
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printf("If you get both correct, you will receive the flag.\n");
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srand(time(NULL));
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int word_length = 5;
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char *word = (char *)malloc((word_length + 1) * sizeof(char));
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for (int i = 0; i < word_length; i++)
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{
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word[i] = (rand() % 26) + 'a';
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}
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word[word_length] = '\0';
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return word;
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}
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int main()
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{
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char *challenge_word = generate_random_word();
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printf("Word: %s\n", challenge_word);
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fflush(stdout);
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char *little_endian = find_little_endian(challenge_word);
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size_t user_little_endian_size = strlen(little_endian);
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char user_little_endian[user_little_endian_size + 1];
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bool correct_flag = false;
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while (!correct_flag)
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{
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printf("Enter the Little Endian representation: ");
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fflush(stdout);
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scanf("%10s", user_little_endian);
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for (size_t i = 0; i < strlen(user_little_endian); i++)
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{
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user_little_endian[i] = toupper(user_little_endian[i]);
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}
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if (strncmp(user_little_endian, little_endian, user_little_endian_size) == 0)
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{
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printf("Correct Little Endian representation!\n");
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fflush(stdout);
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correct_flag = true;
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}
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else
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{
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printf("Incorrect Little Endian representation. Try again!\n");
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fflush(stdout);
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}
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}
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char *big_endian = find_big_endian(challenge_word);
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size_t user_big_endian_size = strlen(big_endian);
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char user_big_endian[user_big_endian_size + 1];
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bool final_flag = false;
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while (!final_flag)
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{
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printf("Enter the Big Endian representation: ");
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fflush(stdout);
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scanf("%10s", user_big_endian);
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for (size_t i = 0; i < strlen(user_big_endian); i++)
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{
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user_big_endian[i] = toupper(user_big_endian[i]);
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}
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if (strncmp(user_big_endian, big_endian, user_big_endian_size) == 0)
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{
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printf("Correct Big Endian representation!\n");
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fflush(stdout);
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final_flag = true;
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}
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else
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{
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printf("Incorrect Big Endian representation. Try again!\n");
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fflush(stdout);
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}
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}
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FILE *flag = fopen("flag.txt", "r");
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if (flag == NULL)
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{
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printf("Flag not found. Please run this on the server\n");
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fflush(stdout);
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exit(0);
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}
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char flag_content[100];
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fgets(flag_content, sizeof(flag_content), flag);
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printf("Congratulations! You found both endian representations correctly!\n");
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fflush(stdout);
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printf("Your Flag is: %s\n", flag_content);
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fflush(stdout);
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exit(0);
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return 0;
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}
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