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

crypto/hmac.h

-// Copyright (c) 2012 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.
-
-// Utility class for calculating the HMAC for a given message. We currently
-// only support SHA1 for the hash algorithm, but this can be extended easily.
-
-#ifndef CRYPTO_HMAC_H_
-#define CRYPTO_HMAC_H_
-
-#include "base/basictypes.h"
-#include "base/compiler_specific.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/strings/string_piece.h"
-#include "crypto/crypto_export.h"
-
-namespace crypto {
-
-// Simplify the interface and reduce includes by abstracting out the internals.
-struct HMACPlatformData;
-class SymmetricKey;
-
-class CRYPTO_EXPORT HMAC {
- public:
-  // The set of supported hash functions. Extend as required.
-  enum HashAlgorithm {
-    SHA1,
-    SHA256,
-  };
-
-  explicit HMAC(HashAlgorithm hash_alg);
-  ~HMAC();
-
-  // Returns the length of digest that this HMAC will create.
-  size_t DigestLength() const;
-
-  // TODO(abarth): Add a PreferredKeyLength() member function.
-
-  // Initializes this instance using |key| of the length |key_length|. Call Init
-  // only once. It returns false on the second or later calls.
-  //
-  // NOTE: the US Federal crypto standard FIPS 198, Section 3 says:
-  //   The size of the key, K, shall be equal to or greater than L/2, where L
-  //   is the size of the hash function output.
-  // In FIPS 198-1 (and SP-800-107, which describes key size recommendations),
-  // this requirement is gone.  But a system crypto library may still enforce
-  // this old requirement.  If the key is shorter than this recommended value,
-  // Init() may fail.
-  bool Init(const unsigned char* key, size_t key_length) WARN_UNUSED_RESULT;
-
-  // Initializes this instance using |key|. Call Init
-  // only once. It returns false on the second or later calls.
-  bool Init(SymmetricKey* key) WARN_UNUSED_RESULT;
-
-  // Initializes this instance using |key|. Call Init only once. It returns
-  // false on the second or later calls.
-  bool Init(const base::StringPiece& key) WARN_UNUSED_RESULT {
-    return Init(reinterpret_cast<const unsigned char*>(key.data()),
-                key.size());
-  }
-
-  // Calculates the HMAC for the message in |data| using the algorithm supplied
-  // to the constructor and the key supplied to the Init method. The HMAC is
-  // returned in |digest|, which has |digest_length| bytes of storage available.
-  bool Sign(const base::StringPiece& data, unsigned char* digest,
-            size_t digest_length) const WARN_UNUSED_RESULT;
-
-  // Verifies that the HMAC for the message in |data| equals the HMAC provided
-  // in |digest|, using the algorithm supplied to the constructor and the key
-  // supplied to the Init method. Use of this method is strongly recommended
-  // over using Sign() with a manual comparison (such as memcmp), as such
-  // comparisons may result in side-channel disclosures, such as timing, that
-  // undermine the cryptographic integrity. |digest| must be exactly
-  // |DigestLength()| bytes long.
-  bool Verify(const base::StringPiece& data,
-              const base::StringPiece& digest) const WARN_UNUSED_RESULT;
-
-  // Verifies a truncated HMAC, behaving identical to Verify(), except
-  // that |digest| is allowed to be smaller than |DigestLength()|.
-  bool VerifyTruncated(
-      const base::StringPiece& data,
-      const base::StringPiece& digest) const WARN_UNUSED_RESULT;
-
- private:
-  HashAlgorithm hash_alg_;
-  scoped_ptr<HMACPlatformData> plat_;
-
-  DISALLOW_COPY_AND_ASSIGN(HMAC);
-};
-
-}  // namespace crypto
-
-#endif  // CRYPTO_HMAC_H_