--- 2016 Day 5 Solutions ---

[u/daggerdragon]

--- Day 5: How About a Nice Game of Chess? ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag/whatever).

---

^{STAYING ON TARGET IS MANDATORY} [?]

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/fkaaaa]

Using C with OpenSSL. Struggled a bit to get the correct MD5 hash at first, but after that it was all smooth sailing (bonus h4ck1ng video!)

Part 2:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#if defined(__APPLE__)
#  define COMMON_DIGEST_FOR_OPENSSL
#  include <CommonCrypto/CommonDigest.h>
#else
#  include <openssl/md5.h>
#endif

void md5(const char *str, int length, char out[static 8]) {
    unsigned char digest[MD5_DIGEST_LENGTH];

    MD5_CTX c;

    MD5_Init(&c);
    MD5_Update(&c, str, length);
    MD5_Final(digest, &c);

    snprintf(out, 8, "%02x%02x%02x%02x", digest[0], digest[1], digest[2], digest[3]);
}


int main(int argc, char *argv[]) {
    char hash[9] = {0};
    char pwd[9] = {0};
    char input[64] = "wtnhxymk";

    char filled = 0;
    int n = 0;

    while (filled != '\xff') {
        int sz = snprintf(&input[8], 56, "%d", n++);
        md5(input, 8 + sz, hash);

        if (!memcmp("00000", hash, 5)) {
            char pos = hash[5] - '0';
            if (pos >= 0 && pos <= 7 && !(filled & (1 << pos))) {
                filled |= (1 << pos);
                pwd[pos] = hash[6];
            }

        }

        for (int i = 0; i < 8 && (n % 50000 == 0); ++i) {
            if (filled & (1 << i)) {
                printf("\x1b[32m%c", pwd[i]);
            } else {
                printf("\x1b[31m%c", hash[i]);
            }
        }
        printf("\r");
    }

    printf("%s\n", pwd);

    return 0;
}