Add support for encrypted WebM files as defined in the RFC.

media/crypto/aes_decryptor.cc

 // Copyright (c) 2012 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 "media/crypto/aes_decryptor.h"
 
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "base/string_piece.h"
 #include "crypto/encryptor.h"
 #include "crypto/symmetric_key.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/decrypt_config.h"
 
 namespace media {
 
-// TODO(xhwang): Get real IV from frames.
-static const char kInitialCounter[] = "0000000000000000";
-
-// Decrypt |input| using |key|.
-// Return a DecoderBuffer with the decrypted data if decryption succeeded.
-// Return NULL if decryption failed.
-static scoped_refptr<DecoderBuffer> DecryptData(const DecoderBuffer& input,
-                                                crypto::SymmetricKey* key) {
-  CHECK(input.GetDataSize());
-  CHECK(key);
-
-  // Initialize encryption data.
-  // The IV must be exactly as long as the cipher block size.
-  crypto::Encryptor encryptor;
-  if (!encryptor.Init(key, crypto::Encryptor::CBC, kInitialCounter)) {
-    DVLOG(1) << "Could not initialize encryptor.";
-    return NULL;
-  }
-
-  std::string decrypted_text;
-  base::StringPiece encrypted_text(
-      reinterpret_cast<const char*>(input.GetData()),
-      input.GetDataSize());
-  if (!encryptor.Decrypt(encrypted_text, &decrypted_text)) {
-    DVLOG(1) << "Could not decrypt data.";
-    return NULL;
-  }
-
-  // TODO(xhwang): Find a way to avoid this data copy.
-  return DecoderBuffer::CopyFrom(
-      reinterpret_cast<const uint8*>(decrypted_text.data()),
-      decrypted_text.size());
-}
-
 AesDecryptor::AesDecryptor() {}
 
 AesDecryptor::~AesDecryptor() {
   STLDeleteValues(&key_map_);
 }
 
 void AesDecryptor::AddKey(const uint8* key_id, int key_id_size,
                           const uint8* key, int key_size) {
   CHECK(key_id && key);
   CHECK_GT(key_id_size, 0);
@@ skipping 31 matching lines @@
   {
     base::AutoLock auto_lock(lock_);
     KeyMap::const_iterator found = key_map_.find(key_id_string);
     if (found == key_map_.end()) {
       DVLOG(1) << "Could not find a matching key for given key ID.";
       return NULL;
     }
     key = found->second;
   }
 
-  scoped_refptr<DecoderBuffer> decrypted = DecryptData(*encrypted, key);
+  scoped_refptr<DecoderBuffer> decrypted =
+      Decryptor::DecryptData(*encrypted, key, 0);
 
   if (decrypted) {
     decrypted->SetTimestamp(encrypted->GetTimestamp());
     decrypted->SetDuration(encrypted->GetDuration());
   }
 
   return decrypted;
 }
 
 }  // namespace media