[webcrypto] Reject AES-GCM tag lengths other than 32, 64, 96, 104, 112, 120, 128.

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 37 matching lines @@
 //  * |key| is a non-null AES-CBC key.
 //  * |iv| is exactly 16 bytes long
 Status EncryptDecryptAesCbc(EncryptOrDecrypt mode,
                             SymKey* key,
                             const CryptoData& data,
                             const CryptoData& iv,
                             blink::WebArrayBuffer* buffer);
 
 // Preconditions:
 //  * |key| is a non-null AES-GCM key.
-//  * |tag_length_bits| is in the range [0, 128].
+//  * |tag_length_bits| is one of {32, 64, 96, 104, 112, 120, 128}
 Status EncryptDecryptAesGcm(EncryptOrDecrypt mode,
                             SymKey* key,
                             const CryptoData& data,
                             const CryptoData& iv,
                             const CryptoData& additional_data,
                             unsigned int tag_length_bits,
                             blink::WebArrayBuffer* buffer);
 
 // Preconditions:
 //  * |key| is non-null.
@@ skipping 99 matching lines @@
 //  * |key| is non-null.
 Status ExportKeySpki(PublicKey* key, blink::WebArrayBuffer* buffer);
 
 }  // namespace platform
 
 }  // namespace webcrypto
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_WEBCRYPTO_PLATFORM_CRYPTO_H_