Implement VerifySignedData() for ECDSA, RSA PKCS#1 and RSA PSS.

net/cert/internal/verify_signed_data.h

Index: net/cert/internal/verify_signed_data.h
diff --git a/net/cert/internal/verify_signed_data.h b/net/cert/internal/verify_signed_data.h
new file mode 100644
index 0000000000000000000000000000000000000000..fc622e8f563ab2edb037393e5eb5d669a78de78b
--- /dev/null
+++ b/net/cert/internal/verify_signed_data.h
@@ -0,0 +1,38 @@
+// Copyright 2015 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 NET_CERT_INTERNAL_VERIFY_SIGNED_DATA_H_
+#define NET_CERT_INTERNAL_VERIFY_SIGNED_DATA_H_
+
+#include "base/compiler_specific.h"
+#include "net/base/net_export.h"
+
+namespace net {
+
+namespace der {
+class Input;
+}  // namespace der
+
+class SignatureAlgorithm;
+
+// Verifies that |signature_value| is a valid signature of |signed_data| using
+// the algorithm |signature_algorithm| and the public key |public_key|.
+//
+//   |signature_algorithm| - The parsed AlgorithmIdentifier
+//   |signed_data| - The blob of data to verify
+//   |signature_value_bit_string| - The DER-encoded BIT STRING representing the
+//       signature's value (to be interpreted according to the signature
+//       algorithm).
+//   |public_key| - A DER-encoded SubjectPublicKeyInfo.
+//
+// Returns true if verification was successful.
+NET_EXPORT bool VerifySignedData(const SignatureAlgorithm& signature_algorithm,
+                                 const der::Input& signed_data,
+                                 const der::Input& signature_value_bit_string,
+                                 const der::Input& public_key)
+    WARN_UNUSED_RESULT;
+
+}  // namespace net
+
+#endif  // NET_CERT_INTERNAL_VERIFY_SIGNED_DATA_H_