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

#define DELTA 0x9e3779b9

void xtea_encrypt(uint32_t v[2], uint32_t const key[4]) {
    uint32_t v0 = v[0], v1 = v[1], sum = 0;
    for (int i = 0; i < 32; i++) {
        v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + key[sum & 3]);
        sum += DELTA;
        v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + key[(sum >> 11) & 3]);
    }
    v[0] = v0;
    v[1] = v1;
}

void hash_file(const char *filename) {
    FILE *f = fopen(filename, "rb");
    if (!f) {
        perror("Erreur ouverture fichier");
        return;
    }

    uint8_t buffer[24];
    uint64_t final_hash[1] = {0};
    size_t bytes_read;

    while ((bytes_read = fread(buffer, 1, 24, f)) > 0) {
        if (bytes_read < 24) {
            memset(buffer + bytes_read, 24 - bytes_read, 24 - bytes_read);
        }

        uint32_t x[2];
        memcpy(x, buffer, 8);

        uint32_t key[4];
        memcpy(key, buffer + 8, 16);

        uint32_t x_orig[2] = {x[0], x[1]};
        xtea_encrypt(x, key);

        x[0] ^= x_orig[0];
        x[1] ^= x_orig[1];

        final_hash[0] ^= ((uint64_t)x[0] << 32) | x[1];
    }

    fclose(f);

    printf("Empreinte (hachage) : %016llx\n", (unsigned long long)final_hash[0]);
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage : %s <fichier>\n", argv[0]);
        return 1;
    }

    hash_file(argv[1]);
    return 0;
}