Add DER parsing of AlgorithmId for signatures.

net/cert/internal/signature_algorithm.h

Index: net/cert/internal/signature_algorithm.h
diff --git a/net/cert/internal/signature_algorithm.h b/net/cert/internal/signature_algorithm.h
new file mode 100644
index 0000000000000000000000000000000000000000..9ecf252d6712032d672b794c9777f34d0c56e9e6
--- /dev/null
+++ b/net/cert/internal/signature_algorithm.h
@@ -0,0 +1,114 @@
+// 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_SIGNATURE_ALGORITHM_H_
+#define NET_CERT_INTERNAL_SIGNATURE_ALGORITHM_H_
+
+#include <stdint.h>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/base/net_export.h"
+
+namespace net {
+
+namespace der {
+class Input;
+}  // namespace der
+
+// The digest algorithm used within a signature.
+enum class DigestAlgorithm {
+  Sha1,
+  Sha256,
+  Sha384,
+  Sha512,
+};
+
+// The signature scheme used within a signature. Parameters are specified
+// separately.
+enum class SignatureAlgorithmId {
+  RsaPkcs1,  // RSA PKCS#1 v1.5
+  RsaPss,    // RSASSA-PSS
+  Ecdsa,     // ECDSA
+};
+
+// Base class for describing algorithm parameters.
+class NET_EXPORT SignatureAlgorithmParameters {
+ public:
+  SignatureAlgorithmParameters() {}
+  virtual ~SignatureAlgorithmParameters(){};
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SignatureAlgorithmParameters);
+};
+
+// Parameters for an RSASSA-PSS signature algorithm.
+//
+// The trailer is assumed to be 1 and the mask generation algorithm to be MGF1,
+// as that is all that is implemented, and any other values while parsing the
+// AlgorithmIdentifier will thus be rejected.
+class NET_EXPORT RsaPssParameters : public SignatureAlgorithmParameters {
+ public:
+  RsaPssParameters(DigestAlgorithm mgf1_hash, uint32_t salt_length);
+
+  bool Equals(const RsaPssParameters* other) const;
+
+  DigestAlgorithm mgf1_hash() const { return mgf1_hash_; }
+  uint32_t salt_length() const { return salt_length_; }
+
+ private:
+  const DigestAlgorithm mgf1_hash_;
+  const uint32_t salt_length_;
+};
+
+// SignatureAlgorithm describes a signature algorithm and its parameters. This
+// corresponds to "AlgorithmIdentifier" from RFC 5280.
+class NET_EXPORT SignatureAlgorithm {
+ public:
+  ~SignatureAlgorithm();
+
+  SignatureAlgorithmId algorithm() const { return algorithm_; }
+  DigestAlgorithm digest() const { return digest_; }
+
+  // Creates a SignatureAlgorithm by parsing a DER-encoded "AlgorithmIdentifier"
+  // (RFC 5280). Returns nullptr on failure.
+  static scoped_ptr<SignatureAlgorithm> CreateFromDer(
+      const der::Input& algorithm_identifier);
+
+  // Creates a new SignatureAlgorithm with the given type and parameters.
+  static scoped_ptr<SignatureAlgorithm> CreateRsaPkcs1(DigestAlgorithm digest);
+  static scoped_ptr<SignatureAlgorithm> CreateEcdsa(DigestAlgorithm digest);
+  static scoped_ptr<SignatureAlgorithm> CreateRsaPss(DigestAlgorithm digest,
+                                                     DigestAlgorithm mgf1_hash,
+                                                     uint32_t salt_length);
+
+  // Returns true if |*this| is equivalent to |other|. This compares both the
+  // algorithm ID and each parameter for equality.
+  bool Equals(const SignatureAlgorithm& other) const WARN_UNUSED_RESULT;
+
+  // The following methods retrieve the parameters for the signature algorithm.
+  //
+  // The correct parameters should be chosen based on the algorithm ID. For
+  // instance a SignatureAlgorithm with |algorithm() == RsaPss| should retrieve
+  // parameters via ParametersForRsaPss().
+  //
+  // The returned pointer is non-owned, and has the same lifetime as |this|.
+  const RsaPssParameters* ParamsForRsaPss() const;
+
+ private:
+  SignatureAlgorithm(SignatureAlgorithmId algorithm,
+                     DigestAlgorithm digest,
+                     scoped_ptr<SignatureAlgorithmParameters> params);
+
+  const SignatureAlgorithmId algorithm_;
+  const DigestAlgorithm digest_;
+  const scoped_ptr<SignatureAlgorithmParameters> params_;
+
+  DISALLOW_COPY_AND_ASSIGN(SignatureAlgorithm);
+};
+
+}  // namespace net
+
+#endif  // NET_CERT_INTERNAL_SIGNATURE_ALGORITHM_H_