crypto: change ECSignatureCreator defaults to match SPDY.

crypto/ec_signature_creator.h

 // Copyright (c) 2012 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 CRYPTO_EC_SIGNATURE_CREATOR_H_
 #define CRYPTO_EC_SIGNATURE_CREATOR_H_
 
+#include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "crypto/crypto_export.h"
 
 namespace crypto {
 
 class ECPrivateKey;
 class ECSignatureCreator;
 
 class CRYPTO_EXPORT ECSignatureCreatorFactory {
  public:
   virtual ~ECSignatureCreatorFactory() {}
 
   virtual ECSignatureCreator* Create(ECPrivateKey* key) = 0;
 };
 
 // Signs data using a bare private key (as opposed to a full certificate).
 // We need this class because SignatureCreator is hardcoded to use
 // RSAPrivateKey.
 class CRYPTO_EXPORT ECSignatureCreator {
  public:
   virtual ~ECSignatureCreator() {}
 
   // Create an instance. The caller must ensure that the provided PrivateKey
   // instance outlives the created ECSignatureCreator.
-  // TODO(rch):  This is currently hard coded to use SHA1. Ideally, we should
+  // TODO(rch):  This is currently hard coded to use SHA256. Ideally, we should
   // pass in the hash algorithm identifier.
   static ECSignatureCreator* Create(ECPrivateKey* key);
 
   // Set a factory to make the Create function return non-standard
   // ECSignatureCreator objects.  Because the ECDSA algorithm involves
   // randomness, this is useful for higher-level tests that want to have
   // deterministic mocked output to compare.
   static void SetFactoryForTesting(ECSignatureCreatorFactory* factory);
 
   // Signs |data_len| bytes from |data| and writes the results into
   // |signature| as a DER encoded ECDSA-Sig-Value from RFC 3279.
   //
   //  ECDSA-Sig-Value ::= SEQUENCE {
   //    r     INTEGER,
   //    s     INTEGER }
   virtual bool Sign(const uint8* data,
                     int data_len,
                     std::vector<uint8>* signature) = 0;
+
+  // DecodeSignature converts from a DER encoded ECDSA-Sig-Value (as produced
+  // by Sign) to a `raw' ECDSA signature which consists of a pair of
+  // big-endian, zero-padded, 256-bit integers, r and s. On success it returns

[wtc, 2012/09/12 22:06:27]

The size of r and s depends on the ECPrivateKey object.
It is fine to say "256-bit" for now because I think we can
only create P-256 ECPrivateKeys.

It seems bad to use different types for input and output.
Is std::string more convenient for the SPDY code?

[agl, 2012/09/13 20:17:59]

I've changed the output to also be a std::vector<uint8>

+  // true and puts the raw signature into |out_raw_sig|.
+  virtual bool DecodeSignature(const std::vector<uint8>& signature,
+                               std::string* out_raw_sig) = 0;
 };
 
 }  // namespace crypto
 
 #endif  // CRYPTO_EC_SIGNATURE_CREATOR_H_