/*
 * gcc -O2 proof.c $(pkg-config --cflags --libs openssl) -o proof
 */
#include <stdio.h>
#include <string.h>
#include <openssl/sha.h>

int main(int argc, char **argv) {
    const char *target = "31C";
    char data[40];

    if (argc < 2) {
        printf("Usage: proof [init]\n");
        return 1;
    }

    memset(data, 'A', sizeof data);
    memcpy(&data[sizeof(data) - 32], argv[1], 32);

    unsigned long *first = (unsigned long *) data;
    unsigned char hash[32];
    do {
        ++*first;
        SHA256((unsigned char *) &data, sizeof(data), hash);
    } while (memcmp(target, hash, strlen(target)) != 0);
    
    write(1, data, sizeof(data) - 32);
    return 0;
}