/** HMAC initialization  * @param ctx HMAC context  * @param key Key, 16 bytes  * @param hsize Expected hash length in bytes  * @param ctr 64-bit counter to prevent replay attacks, may be 0  * @return Actual hash length in bytes (0 if bogus)  */ int b2s_hmac_init(blake2s_state *S, const uint8_t *key, int hsize, uint64_t ctr); /** HMAC append byte  * @param ctx HMAC context  * @param c Byte to add to HMAC  */ void b2s_hmac_putc(blake2s_state *S, uint8_t c); /** HMAC append byte  * @param ctx HMAC context  * @param out Output hash  * @return Hash length in bytes  */ int b2s_hmac_final(blake2s_state *S, uint8_t *out);