Abstracts SHA256 context for NSS / OpenSSL.

base/sha2_openssl.cc

 // Copyright (c) 2010 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.
 
 #include "base/sha2.h"
 
 #include <openssl/ssl.h>
 
 #include "base/basictypes.h"
 #include "base/openssl_util.h"
 #include "base/stl_util-inl.h"
 
 namespace base {
 
 void SHA256HashString(const std::string& str, void* output, size_t len) {
   COMPILE_ASSERT(SHA256_LENGTH == SHA256_DIGEST_LENGTH,
                  API_and_OpenSSL_SHA256_lengths_must_match);
   ScopedOpenSSLSafeSizeBuffer<SHA256_DIGEST_LENGTH> result(
       reinterpret_cast<unsigned char*>(output), len);
   ::SHA256(reinterpret_cast<const unsigned char*>(str.data()), str.size(),
            result.safe_buffer());
 }
 
 std::string SHA256HashString(const std::string& str) {
   std::string output(SHA256_LENGTH, 0);
   SHA256HashString(str, string_as_array(&output), output.size());
   return output;
 }
 
+namespace {
+
+class SHA256ContextOpenSSL : public SHA256Context {
+ public:
+  SHA256ContextOpenSSL() {
+    SHA256_Init(&ctx_);
+  }
+
+  virtual ~SHA256ContextOpenSSL() {
+    OPENSSL_cleanse(&ctx_, sizeof(ctx_));
+  }
+
+  virtual void Update(const std::string& str) {
+    SHA256_Update(&ctx_, reinterpret_cast<const unsigned char*>(str.data()),
+                  str.size());
+  }
+
+  virtual void Finish(void* output, size_t len) {
+    ScopedOpenSSLSafeSizeBuffer<SHA256_DIGEST_LENGTH> result(
+        reinterpret_cast<unsigned char*>(output), len);
+    SHA256_Final(result.safe_buffer(), &ctx_);
+  }
+
+ private:
+  SHA256_CTX ctx_;
+};
+
+}  // namespace
+
+SHA256Context* SHA256Context::Create() {
+  return new SHA256ContextOpenSSL();
+}
+
 }  // namespace base