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// 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.
#include "crypto/hmac.h"
#include <algorithm>
#include "base/logging.h"
#include "crypto/secure_util.h"
#include "crypto/symmetric_key.h"
namespace crypto {
bool HMAC::Init(SymmetricKey* key) {
std::string raw_key;
bool result = key->GetRawKey(&raw_key) && Init(raw_key);
// Zero out key copy. This might get optimized away, but one can hope.
// Using std::string to store key info at all is a larger problem.
std::fill(raw_key.begin(), raw_key.end(), 0);
return result;
}
size_t HMAC::DigestLength() const {
switch (hash_alg_) {
case SHA1:
return 20;
case SHA256:
return 32;
default:
NOTREACHED();
return 0;
}
}
bool HMAC::Verify(const base::StringPiece& data,
const base::StringPiece& digest) const {
if (digest.size() != DigestLength())
return false;
return VerifyTruncated(data, digest);
}
bool HMAC::VerifyTruncated(const base::StringPiece& data,
const base::StringPiece& digest) const {
if (digest.empty())
return false;
size_t digest_length = DigestLength();
scoped_array<unsigned char> computed_digest(
new unsigned char[digest_length]);
if (!Sign(data, computed_digest.get(), static_cast<int>(digest_length)))
return false;
return SecureMemEqual(digest.data(), computed_digest.get(),
std::min(digest.size(), digest_length));
}
} // namespace crypto
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