Reland "Cut down /crypto and switch what is left of it to boringssl".

crypto/hkdf.h

-// 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 <vector>
-
-#include "base/basictypes.h"
-#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);
-  ~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> 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_