Introduce SignatureCreator.

base/crypto/signature_creator.h

Index: base/crypto/signature_creator.h
diff --git a/base/crypto/signature_creator.h b/base/crypto/signature_creator.h
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+++ b/base/crypto/signature_creator.h
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+// Copyright (c) 2009 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 BASE_CRYPTO_SIGNATURE_CREATOR_H_
+#define BASE_CRYPTO_SIGNATURE_CREATOR_H_
+
+#if defined(OS_WIN)
+#include <windows.h>
+#include <wincrypt.h>
+#else
+// TODO(PORT)
+#endif
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/crypto/rsa_private_key.h"
+
+namespace base {
+
+// Signs data using a bare private key (as opposed to a full certificate).
+// Currently can only sign data using SHA-1 with RSA encryption.
+class SignatureCreator {
+ public:
+  // Create an instance. The caller must ensure that the provided PrivateKey
+  // instance outlives the created SignatureCreator.
+  static SignatureCreator* Create(RSAPrivateKey* key);
+
+  ~SignatureCreator();
+
+  // Update the signature with more data.
+  bool Update(const uint8* data_part, int data_part_len);
+
+  // Finalize the signature.
+  bool Final(std::vector<uint8>* signature);
+
+ private:
+  // Private constructor. Use the Create() method instead.
+  SignatureCreator() {}
+
+  RSAPrivateKey* key_;
+
+#if defined(OS_WIN)
+  HCRYPTHASH hash_object_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(SignatureCreator);
+};
+
+}  // namespace base
+
+#endif  // BASE_CRYPTO_SIGNATURE_CREATOR_H_