c hmac

1. hmac.pl

#!/usr/bin/perl

use strict;
use warnings;
use Digest::SHA qw(hmac_sha1_hex);

print hmac_sha1_hex("my data", "secret key") . "\n";

2. hmac.c

#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <openssl/hmac.h>

int main() {

        char* key = "secret key";
        char* data = "my data";
        unsigned int result_len = 40;
        unsigned char* result = malloc(sizeof(unsigned char) * result_len);

        HMAC_CTX ctx;
        HMAC_CTX_init(&ctx);
        HMAC_Init_ex(&ctx, (unsigned char*) key, strlen(key), EVP_sha1(), NULL);
        HMAC_Update(&ctx, (unsigned char*) data, strlen(data));
        HMAC_Final(&ctx, result, &result_len);
        HMAC_CTX_cleanup(&ctx);

        //printf("output  : %s\n", (char*)result);

        printf("output  : ");
        int i;
        for(i=0; i<result_len; i++)
          printf("%.2x", result[i]);
        printf("\n");

        printf("expected: %s\n", "97a62219092f3ddab3707cc9e85e63e926f45c87");
        
        return 0;
}

gistfile1.sh

$ perl hmac.pl
97a62219092f3ddab3707cc9e85e63e926f45c87

$ gcc -Wall -lcrypto hmac.c -o hmac  && ./hmac
output  : ��"   /=ڳp|��^c�&�\�
expected: 97a62219092f3ddab3707cc9e85e63e926f45c87