HMAC_MD5_Update
HMAC_MD5_Update(&md5, "Hi There", 8);
HMAC_MD5_Update(&md5, "what do ya want for nothing?", 28);
HMAC_MD5_Update(&md5, data, sizeof data);
void HMAC_MD5_Update(HMAC_MD5_CTX *, const u_int8_t *, u_int)
HMAC_MD5_Update(&ctx.md5, (u_int8_t *)key, len);