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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
#pragma once
#include <stdint.h>
#include "crypto/s2n_hmac.h"
#include "utils/s2n_blob.h"
/*
* Label structure is `opaque label<7..255> = "tls13 " + Label` per RFC8446.
* So, we have 255-sizeof("tls13 ") = 249, the maximum label length.
*
* Note that all labels defined by RFC 8446 are <12 characters, which
* avoids an extra hash iteration. However, the exporter functionality
* (s2n_connection_tls_exporter) allows for longer labels.
*/
#define S2N_MAX_HKDF_EXPAND_LABEL_LENGTH 249
int s2n_hkdf(struct s2n_hmac_state *hmac, s2n_hmac_algorithm alg, const struct s2n_blob *salt,
const struct s2n_blob *key, const struct s2n_blob *info, struct s2n_blob *output);
int s2n_hkdf_extract(struct s2n_hmac_state *hmac, s2n_hmac_algorithm alg, const struct s2n_blob *salt,
const struct s2n_blob *key, struct s2n_blob *pseudo_rand_key);
int s2n_hkdf_expand_label(struct s2n_hmac_state *hmac, s2n_hmac_algorithm alg, const struct s2n_blob *secret, const struct s2n_blob *label,
const struct s2n_blob *context, struct s2n_blob *output);
bool s2n_libcrypto_supports_hkdf();
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