Language: C

Source code:

#include <stdio.h> #include <stdlib.h> #include <string.h> // The flag looks like FLAG{md5} const char *flag = "464c41477b32653135356238376435383234653835656634313039346165633761383364637d"; int check(const char *text) { char buf[512]; memset(buf, 0, sizeof(buf)); char *ptr = buf; for (size_t i = 0; text[i]; i++) { sprintf(ptr, "%02x", text[i]); ptr += 2; } return strcmp(flag, buf); } int main(int argc, char *argv[]) { char buf[256]; memset(buf, 0, sizeof(buf)); printf("Enter your flag: "); fgets(buf, sizeof(buf), stdin); buf[strlen(buf)-1] = '\0'; if (!check(buf)) { printf("[+] You win!\n"); } else { printf("[-] You lose!\n"); } exit(EXIT_SUCCESS); }

Compiled Linux binary: crackme
Compiled Windows binary: crackme.exe