int8_t check_param_nonce(unsigned char* message, uint16_t full_message_length, mpz_t B, uint8_t *nonce, RSA_key *key) {
    uint16_t position = 0, data_length = 0, i = 0;
    unsigned char nonce_hex[33] = {"\x00"};
    uint8_t ok = 1;
    ok &= check_input_and_copy_str_to_bignum(message, B, &position, 5, "OK:B=", full_message_length);
    if (strncmp(message + position + 1, "nonce=", 6) != 0) {
        return 0;
    }
    position += 7;
    if ((full_message_length - position < 32) || (message[position + 32] != 124)) {
        return 0;
    }
    memcpy(nonce_hex, &message[position], 32);
    ok &= hex_to_bytes(nonce, nonce_hex);
    if (!ok) {
        return 0;
    }
    return 1;
}

unsigned char *bytes_to_hex(uint8_t *bytes, uint8_t length) {
    unsigned char chr[3] = {0};
    unsigned char *hex;
    hex = malloc(2 * length + 1);
    if (hex == NULL) {
        return NULL;
    }
    memset(hex, 0, 2 * length + 1);
    for (int8_t i = 0; i < length; i++) {
        if (bytes[i] == 0) {
            memcpy(hex + 2 * i, "00", 2);
            }
        else {
            sprintf(chr, "%x", bytes[i]);
            if (chr[1] == 0) {
                chr[1] = chr[0];
                chr[0] = '0';
            }
            memcpy(hex + 2 * i, chr, 2);
        }
    }
    return hex;
}