AU: Switch to 2048 bit RSA keys; Pad SHA256 hashes appropriately.

payload_signer.h

 // Copyright (c) 2010 The Chromium OS 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 CHROMEOS_PLATFORM_UPDATE_ENGINE_PAYLOAD_SIGNER_H__
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_PAYLOAD_SIGNER_H__
 
 #include <string>
 #include <vector>
 
@@ skipping 49 matching lines @@
   static bool VerifySignature(const std::vector<char>& signature_blob,
                               const std::string& public_key_path,
                               std::vector<char>* out_hash_data);
 
   // Returns true if the payload in |payload_path| is signed and its hash can be
   // verified using the public key in |public_key_path|. Returns false
   // otherwise.
   static bool VerifySignedPayload(const std::string& payload_path,
                                   const std::string& public_key_path);
 
+  // Pads a SHA256 hash so that it may be encrypted/signed with RSA2048.

[gauravsh, 2011/03/29 23:04:05]

just a add a comment that this pads using the PKCS#1 v1.5 scheme. (there are
multiple types of padding schemes) 

[adlr, 2011/03/30 19:40:14]

Done.

+  // Returns true on success, false otherwise.
+  static bool PadRSA2048SHA256Hash(std::vector<char>* hash);

[gauravsh, 2011/03/29 23:04:05]

comment on what |hash| is? Also that in-place modifies the hash.

[adlr, 2011/03/30 19:40:14]

Done.

  private:
   // This should never be constructed
   DISALLOW_IMPLICIT_CONSTRUCTORS(PayloadSigner);
 };
 
 }  // namespace chromeos_update_engine
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_PAYLOAD_SIGNER_H__