Add a CreatePSS method to SignatureCreator to permit the generation of PSS signatures.

crypto/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_SIGNATURE_CREATOR_H_
 #define CRYPTO_SIGNATURE_CREATOR_H_
 
 #include <vector>
 
 #include "build/build_config.h"
@@ skipping 22 matching lines @@
     SHA256,
   };
 
   ~SignatureCreator();
 
   // Create an instance. The caller must ensure that the provided PrivateKey
   // instance outlives the created SignatureCreator. Uses the HashAlgorithm
   // specified.
   static SignatureCreator* Create(RSAPrivateKey* key, HashAlgorithm hash_alg);
 
+  // Create an instance. The caller must ensure that the provided PrivateKey
+  // instance outlives the created SignatureCreator. Uses the HashAlgorithm
+  // specified. The generated signature will be in the RSA-PSS format.
+  static SignatureCreator* CreatePSS(RSAPrivateKey* key,
+                                     HashAlgorithm hash_alg);
 
   // Signs the precomputed |hash_alg| digest |data| using private |key| as
   // specified in PKCS #1 v1.5.

[Ryan Sleevi, 2015/08/25 20:01:38]

This of course would be inconsistent with your proposed change :)

   static bool Sign(RSAPrivateKey* key,
                    HashAlgorithm hash_alg,
                    const uint8* data,
                    int data_len,
                    std::vector<uint8>* signature);
 
   // Update the signature with more data.
   bool Update(const uint8* data_part, int data_part_len);
 
   // Finalize the signature.
   bool Final(std::vector<uint8>* signature);
 
  private:
+  static SignatureCreator* CreateImpl(RSAPrivateKey* key,

[Ryan Sleevi, 2015/08/25 20:01:38]

This doesn't actually need to be static, does it?

+                                      HashAlgorithm hash_alg,
+                                      bool use_pss);
+
   // Private constructor. Use the Create() method instead.
   SignatureCreator();
 
 #if defined(USE_OPENSSL)
   EVP_MD_CTX* sign_context_;
 #elif defined(USE_NSS_CERTS) || defined(OS_WIN) || defined(OS_MACOSX)
   SGNContextStr* sign_context_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(SignatureCreator);
 };
 
 }  // namespace crypto
 
 #endif  // CRYPTO_SIGNATURE_CREATOR_H_