| // Copyright (c) 2013 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 CRYPTO_HKDF_H_ |
| #define CRYPTO_HKDF_H_ |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| #include <vector> |
| |
| #include "base/strings/string_piece.h" |
| #include "crypto/crypto_export.h" |
| |
| namespace crypto { |
| |
| // HKDF 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 CRYPTO_EXPORT HKDF { |
| 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. |
| HKDF(const base::StringPiece& secret, |
| const base::StringPiece& salt, |
| const base::StringPiece& 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. |
| HKDF(const base::StringPiece& secret, |
| const base::StringPiece& salt, |
| const base::StringPiece& 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); |
| ~HKDF(); |
| |
| base::StringPiece client_write_key() const { |
| return client_write_key_; |
| } |
| base::StringPiece client_write_iv() const { |
| return client_write_iv_; |
| } |
| base::StringPiece server_write_key() const { |
| return server_write_key_; |
| } |
| base::StringPiece server_write_iv() const { |
| return server_write_iv_; |
| } |
| base::StringPiece subkey_secret() const { |
| return subkey_secret_; |
| } |
| |
| private: |
| std::vector<uint8_t> output_; |
| |
| base::StringPiece client_write_key_; |
| base::StringPiece server_write_key_; |
| base::StringPiece client_write_iv_; |
| base::StringPiece server_write_iv_; |
| base::StringPiece subkey_secret_; |
| }; |
| |
| } // namespace crypto |
| |
| #endif // CRYPTO_HKDF_H_ |