Standalone implementation of HMAC()
+ EVP_sha1()
in OpenSSL
#include "hmac/hmac.h"
void hmac_sha1(const uint8_t *k, /* secret key */
size_t lk, /* length of the key in bytes */
const uint8_t *d, /* data */
size_t ld, /* length of data in bytes */
uint8_t *out, /* output buffer, at least "t" bytes */
size_t *t);