Certificate Transparency: Parse Signed Tree Heads and validate them

net/cert/ct_log_verifier.h

 // Copyright 2013 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_CT_LOG_VERIFIER_H_
 #define NET_CERT_CT_LOG_VERIFIER_H_
 
 #include <string>
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_piece.h"
 #include "net/base/net_export.h"
 #include "net/cert/signed_certificate_timestamp.h"
 
 // Forward declare the crypto types to avoid having to include the full
 // headers.
 #if defined(USE_OPENSSL)
 typedef struct evp_pkey_st EVP_PKEY;
 #else
 typedef struct SECKEYPublicKeyStr SECKEYPublicKey;
 #endif
 
 namespace net {
 
+namespace ct {
+struct SignedTreeHead;
+}  // namespace ct
+
 // Class for verifying Signed Certificate Timestamps (SCTs) provided by a
 // specific log (whose identity is provided during construction).
 class NET_EXPORT CTLogVerifier {
  public:
   // Creates a new CTLogVerifier that will verify SignedCertificateTimestamps
   // using |public_key|, which is a DER-encoded SubjectPublicKeyInfo.
   // If |public_key| refers to an unsupported public key, returns NULL.
   // |description| is a textual description of the log.
   static scoped_ptr<CTLogVerifier> Create(
       const base::StringPiece& public_key,
       const base::StringPiece& description);
 
   ~CTLogVerifier();
 
   // Returns the log's key ID (RFC6962, Section 3.2)
   const std::string& key_id() const { return key_id_; }
   // Returns the log's human-readable description.
   const std::string& description() const { return description_; }
 
   // Verifies that |sct| contains a valid signature for |entry|.
   bool Verify(const ct::LogEntry& entry,
               const ct::SignedCertificateTimestamp& sct);
 
+  // Verifies and sets |signed_tree_head|. If |signed_tree_head|'s signature is
+  // valid, stores it and returns true. Otherwise, discards the sth and
+  // returns false.
+  bool SetSignedTreeHead(scoped_ptr<ct::SignedTreeHead> signed_tree_head);
+
  private:
   FRIEND_TEST_ALL_PREFIXES(CTLogVerifierTest, VerifySignature);
 
   CTLogVerifier();
 
   // Performs crypto-library specific initialization.
   bool Init(const base::StringPiece& public_key,
             const base::StringPiece& description);
 
   // Performs the underlying verification using the selected public key. Note
   // that |signature| contains the raw signature data (eg: without any
   // DigitallySigned struct encoding).
   bool VerifySignature(const base::StringPiece& data_to_sign,
                        const base::StringPiece& signature);
 
+  // Returns true if the signature and hash algorithms in |signature|
+  // match those of the log
+  bool SignatureParametersMatch(const ct::DigitallySigned& signature);
+
   std::string key_id_;
   std::string description_;
   ct::DigitallySigned::HashAlgorithm hash_algorithm_;
   ct::DigitallySigned::SignatureAlgorithm signature_algorithm_;
+  scoped_ptr<ct::SignedTreeHead> sth_;

[Ryan Sleevi, 2014/04/25 23:33:19]

s/sth_/signed_tree_head_/

[Eran Messeri, 2014/04/29 15:22:24]

Done.

 
 #if defined(USE_OPENSSL)
   EVP_PKEY* public_key_;
 #else
   SECKEYPublicKey* public_key_;
 #endif
 };
 
 }  // namespace net
 
 #endif  // NET_CERT_CT_LOG_VERIFIER_H_