Function hmac_init_pad

freebsd/opencrypto/crypto.c:412–441

}

static void
hmac_init_pad(const struct auth_hash *axf, const char *key, int klen,
    void *auth_ctx, uint8_t padval)
{
	uint8_t hmac_key[HMAC_MAX_BLOCK_LEN];
	u_int i;

	KASSERT(axf->blocksize <= sizeof(hmac_key),
	    ("Invalid HMAC block size %d", axf->blocksize));

	/*
	 * If the key is larger than the block size, use the digest of
	 * the key as the key instead.
	 */
	memset(hmac_key, 0, sizeof(hmac_key));
	if (klen > axf->blocksize) {
		axf->Init(auth_ctx);
		axf->Update(auth_ctx, key, klen);
		axf->Final(hmac_key, auth_ctx);
		klen = axf->hashsize;
	} else
		memcpy(hmac_key, key, klen);

	for (i = 0; i < axf->blocksize; i++)
		hmac_key[i] ^= padval;

	axf->Init(auth_ctx);
	axf->Update(auth_ctx, hmac_key, axf->blocksize);
	explicit_bzero(hmac_key, sizeof(hmac_key));
}

void
hmac_init_ipad(const struct auth_hash *axf, const char *key, int klen,