Add a locked version of CryptAcquireContext

base/crypto/capi_util.h

+// 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.
+
+#ifndef BASE_CRYPTO_CAPI_UTIL_H_
+#define BASE_CRYPTO_CAPI_UTIl_H_
+
+#include <windows.h>
+#include <wincrypt.h>
+
+namespace base {
+
+// CryptAcquireContext when passed CRYPT_NEWKEYSET or CRYPT_DELETEKEYSET in
+// flags is not thread-safe. For such calls, we create a global lock to
+// synchronize it.
+//
+// From "Threading Issues with Cryptographic Service Providers",
+// <http://msdn.microsoft.com/en-us/library/aa388149(v=VS.85).aspx>:
+//
+// "The CryptAcquireContext function is generally thread safe unless
+// CRYPT_NEWKEYSET or CRYPT_DELETEKEYSET is specified in the dwFlags
+// parameter."
+BOOL CryptAcquireContextLocked(HCRYPTPROV* prov,

[wtc, 2010/06/23 16:44:15]

Suggestion for future work: also add CryptoAcquireContextUnlocked.
Change all of our calls to CryptAcquireContext to either our Locked or
Unlocked versions.  In Locked and Unlocked, CHECK or DCHECK the 'flags'
argument has or doesn't has the expected flags.

Then, in the future we can easily search for all instances of
CryptoAcquireContext in our source tree and audit the proper use of the
Locked version.

+                               const TCHAR* container,
+                               const TCHAR* provider,
+                               DWORD prov_type,
+                               DWORD flags);
+
+}  // namespace base
+
+#endif  // BASE_CRYPTO_CAPI_UTIl_H_