Generalize crypto::SignatureCreator to allow choice of hash function, so as to support SHA256 (not …

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"
 #include "base/basictypes.h"
 #include "crypto/crypto_export.h"
 
 #if defined(USE_OPENSSL)
 // Forward declaration for openssl/*.h
 typedef struct env_md_ctx_st EVP_MD_CTX;
 #elif defined(USE_NSS) || defined(OS_WIN) || defined(OS_MACOSX)
 // Forward declaration.
 struct SGNContextStr;
 #endif
 
 namespace crypto {
 
 class RSAPrivateKey;
 
 // Signs data using a bare private key (as opposed to a full certificate).
-// Currently can only sign data using SHA-1 with RSA encryption.
+// Currently can only sign data using SHA-1 or SHA-256 with RSA PKCS#1v1.5.
 class CRYPTO_EXPORT SignatureCreator {
  public:
+  // The set of supported hash functions. Extend as required.
+  enum HashAlgorithm {
+    SHA1,
+    SHA256,
+  };
+
   ~SignatureCreator();
 
   // Create an instance. The caller must ensure that the provided PrivateKey
-  // instance outlives the created SignatureCreator.
-  static SignatureCreator* Create(RSAPrivateKey* key);
+  // instance outlives the created SignatureCreator. Uses the HashAlgorithm
+  // specified.
+  static SignatureCreator* Create(RSAPrivateKey* key, HashAlgorithm hash_alg);
 
-  // Signs the precomputed SHA-1 digest |data| using private |key| as
+
+  // Signs the precomputed |hash_alg| digest |data| using private |key| as
   // specified in PKCS #1 v1.5.
   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:
   // Private constructor. Use the Create() method instead.
   SignatureCreator();
 
   RSAPrivateKey* key_;
 
 #if defined(USE_OPENSSL)
   EVP_MD_CTX* sign_context_;
 #elif defined(USE_NSS) || defined(OS_WIN) || defined(OS_MACOSX)
   SGNContextStr* sign_context_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(SignatureCreator);
 };
 
 }  // namespace crypto
 
 #endif  // CRYPTO_SIGNATURE_CREATOR_H_