blake2s_hmac
void blake2s_hmac(uint8_t *out, const uint8_t *in, const uint8_t *key,
blake2s_hmac(sec, x, ck, BLAKE2S_HASH_SIZE, x_len, NOISE_HASH_LEN);
blake2s_hmac(out, out, sec, BLAKE2S_HASH_SIZE, 1, BLAKE2S_HASH_SIZE);
blake2s_hmac(out, out, sec, BLAKE2S_HASH_SIZE, BLAKE2S_HASH_SIZE + 1,
blake2s_hmac(out, out, sec, BLAKE2S_HASH_SIZE, BLAKE2S_HASH_SIZE + 1,