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// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef QUICHE_QUIC_CORE_CRYPTO_QUIC_HKDF_H_
#define QUICHE_QUIC_CORE_CRYPTO_QUIC_HKDF_H_
#include <vector>
#include "absl/strings/string_view.h"
#include "quiche/quic/platform/api/quic_export.h"
namespace quic {
// QuicHKDF implements the key derivation function specified in RFC 5869
// (using SHA-256) and outputs key material, as needed by QUIC.
// See https://tools.ietf.org/html/rfc5869 for details.
class QUIC_EXPORT_PRIVATE QuicHKDF {
public:
// |secret|: the input shared secret (or, from RFC 5869, the IKM).
// |salt|: an (optional) public salt / non-secret random value. While
// optional, callers are strongly recommended to provide a salt. There is no
// added security value in making this larger than the SHA-256 block size of
// 64 bytes.
// |info|: an (optional) label to distinguish different uses of HKDF. It is
// optional context and application specific information (can be a zero-length
// string).
// |key_bytes_to_generate|: the number of bytes of key material to generate
// for both client and server.
// |iv_bytes_to_generate|: the number of bytes of IV to generate for both
// client and server.
// |subkey_secret_bytes_to_generate|: the number of bytes of subkey secret to
// generate, shared between client and server.
QuicHKDF(absl::string_view secret, absl::string_view salt,
absl::string_view info, size_t key_bytes_to_generate,
size_t iv_bytes_to_generate, size_t subkey_secret_bytes_to_generate);
// An alternative constructor that allows the client and server key/IV
// lengths to be different.
QuicHKDF(absl::string_view secret, absl::string_view salt,
absl::string_view info, size_t client_key_bytes_to_generate,
size_t server_key_bytes_to_generate,
size_t client_iv_bytes_to_generate,
size_t server_iv_bytes_to_generate,
size_t subkey_secret_bytes_to_generate);
~QuicHKDF();
absl::string_view client_write_key() const { return client_write_key_; }
absl::string_view client_write_iv() const { return client_write_iv_; }
absl::string_view server_write_key() const { return server_write_key_; }
absl::string_view server_write_iv() const { return server_write_iv_; }
absl::string_view subkey_secret() const { return subkey_secret_; }
absl::string_view client_hp_key() const { return client_hp_key_; }
absl::string_view server_hp_key() const { return server_hp_key_; }
private:
std::vector<uint8_t> output_;
absl::string_view client_write_key_;
absl::string_view server_write_key_;
absl::string_view client_write_iv_;
absl::string_view server_write_iv_;
absl::string_view subkey_secret_;
absl::string_view client_hp_key_;
absl::string_view server_hp_key_;
};
} // namespace quic
#endif // QUICHE_QUIC_CORE_CRYPTO_QUIC_HKDF_H_
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