[webcrypto] Add raw symmetric key AES-KW wrap/unwrap for NSS.

content/renderer/webcrypto/platform_crypto.h

 // Copyright 2014 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 CONTENT_RENDERER_WEBCRYPTO_PLATFORM_CRYPTO_H_
 #define CONTENT_RENDERER_WEBCRYPTO_PLATFORM_CRYPTO_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "third_party/WebKit/public/platform/WebArrayBuffer.h"
@@ skipping 158 matching lines @@
                       blink::WebCryptoKey* key);
 
 // Preconditions:
 //  * |key| is non-null.
 Status ExportKeyRaw(SymKey* key, blink::WebArrayBuffer* buffer);
 
 // Preconditions:
 //  * |key| is non-null.
 Status ExportKeySpki(PublicKey* key, blink::WebArrayBuffer* buffer);
 
+// Preconditions:
+//  * |wrapping_key| is non-null
+//  * |key| is non-null
+Status WrapSymKeyAesKw(SymKey* wrapping_key,
+                       SymKey* key,
+                       blink::WebArrayBuffer* buffer);
+
+// Preconditions:
+//  * |wrapping_key| is non-null
+//  * |key| is non-null
+//  * |algorithm.id()| is for a symmetric key algorithm.
+//  * |wrapped_key_data| is at least 24 bytes and a multiple of 8 bytes

[eroman, 2014/03/01 01:13:54]

This is not currently guranteed as the checks are done in platform_crypto_nss.cc
rather than shared_crypto.cc. Please move the checks over to shared_crypto.cc so
this comment holds.

[padolph, 2014/03/01 01:55:01]

Done.

+Status UnwrapSymKeyAesKw(const CryptoData& wrapped_key_data,
+                         SymKey* wrapping_key,
+                         const blink::WebCryptoAlgorithm& algorithm,
+                         bool extractable,
+                         blink::WebCryptoKeyUsageMask usage_mask,
+                         blink::WebCryptoKey* key);
+
 }  // namespace platform
 
 }  // namespace webcrypto
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_WEBCRYPTO_PLATFORM_CRYPTO_H_