Abstracts SHA256 context for NSS / OpenSSL.

base/sha2_openssl.cc

Index: base/sha2_openssl.cc
diff --git a/base/sha2_openssl.cc b/base/sha2_openssl.cc
index afbce2f4f3485b530e9f4eea0fca471266f914f4..e54de6a501b6fa4401aa7855ff4b26d403efdf10 100644
--- a/base/sha2_openssl.cc
+++ b/base/sha2_openssl.cc
@@ -27,4 +27,37 @@ std::string SHA256HashString(const std::string& str) {
   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