Change WebM parser to treat IVs from encrypted WebM as raw data.

media/crypto/aes_decryptor_unittest.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 <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
-#include "base/sys_byteorder.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/decrypt_config.h"
 #include "media/base/mock_filters.h"
 #include "media/crypto/aes_decryptor.h"
 #include "media/webm/webm_constants.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using ::testing::_;
 using ::testing::Gt;
@@ skipping 64 matching lines @@
     "Original data.", 14,
     // key_id
     { 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,
       0x2c, 0x2d, 0x2e, 0x2f, 0x30
       }, 13,
     // key
     { 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38,
       0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40
       }, 16,
     // encrypted_data
-    { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-      0x01, 0x9c, 0x71, 0x26, 0x57, 0x3e, 0x25, 0x37,
+    { 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+      0x00, 0x9c, 0x71, 0x26, 0x57, 0x3e, 0x25, 0x37,
       0xf7, 0x31, 0x81, 0x19, 0x64, 0xce, 0xbc
       }, 23
   },
   {
     // plaintext
     "Changed Original data.", 22,
     // key_id
     { 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,
       0x2c, 0x2d, 0x2e, 0x2f, 0x30
       }, 13,
@@ skipping 47 matching lines @@
   0xfa, 0x9d, 0x18, 0x43, 0x1e, 0x96, 0x71, 0xb5,
   0xbf, 0xf5, 0x30, 0x53, 0x9a, 0x20, 0xdf, 0x95
 };
 
 static const SubsampleEntry kSubsampleEntries[] = {
   { 2, 7 },
   { 3, 11 },
   { 1, 0 }
 };
 
-// Returns a 16 byte CTR counter block. The CTR counter block format is a
-// CTR IV appended with a CTR block counter. |iv| is a CTR IV. |iv_size| is
-// the size of |iv| in bytes.
+// Generates a 16 byte CTR counter block. The CTR counter block format is a
+// CTR IV appended with a CTR block counter. |iv| is an 8 byte CTR IV.
+// |iv_size| is the size of |iv| in btyes. Returns a string of
+// kDecryptionKeySize bytes.
 static std::string GenerateCounterBlock(const uint8* iv, int iv_size) {
-  const int kDecryptionKeySize = 16;
   CHECK_GT(iv_size, 0);
-  CHECK_LE(iv_size, kDecryptionKeySize);
+  CHECK_LE(iv_size, DecryptConfig::kDecryptionKeySize);
 
   std::string counter_block(reinterpret_cast<const char*>(iv), iv_size);
-  counter_block.append(kDecryptionKeySize - iv_size, 0);
+  counter_block.append(DecryptConfig::kDecryptionKeySize - iv_size, 0);
   return counter_block;
 }
 
 // Creates a WebM encrypted buffer that the demuxer would pass to the
 // decryptor. |data| is the payload of a WebM encrypted Block. |key_id| is
 // initialization data from the WebM file. Every encrypted Block has
 // a signal byte prepended to a frame. If the frame is encrypted then an IV is
 // prepended to the Block. Current encrypted WebM request for comments
 // specification is here
 // http://wiki.webmproject.org/encryption/webm-encryption-rfc
 static scoped_refptr<DecoderBuffer> CreateWebMEncryptedBuffer(
     const uint8* data, int data_size,
     const uint8* key_id, int key_id_size) {
   scoped_refptr<DecoderBuffer> encrypted_buffer = DecoderBuffer::CopyFrom(
       data, data_size);
   CHECK(encrypted_buffer);
 
   uint8 signal_byte = data[0];
-  int data_offset = sizeof(signal_byte);
+  int data_offset = kWebMSignalByteSize;

[xhwang, 2012/10/15 20:09:04]

nit: dcheck that kWebMSignalByteSize == 1 before we do "uint8 signal_byte =
data[0];"?

[fgalligan1, 2012/10/15 21:07:52]

Done.

 
   // Setting the DecryptConfig object of the buffer while leaving the
   // initialization vector empty will tell the decryptor that the frame is
   // unencrypted.
   std::string counter_block_str;
 
   if (signal_byte & kWebMFlagEncryptedFrame) {
-    uint64 network_iv;
-    memcpy(&network_iv, data + data_offset, sizeof(network_iv));
-    const uint64 iv = base::NetToHost64(network_iv);
-    counter_block_str =
-        GenerateCounterBlock(reinterpret_cast<const uint8*>(&iv), sizeof(iv));
-    data_offset += sizeof(iv);
+    counter_block_str = GenerateCounterBlock(data + data_offset, kWebMIvSize);
+    data_offset += kWebMIvSize;
   }
 
   encrypted_buffer->SetDecryptConfig(
       scoped_ptr<DecryptConfig>(new DecryptConfig(
           std::string(reinterpret_cast<const char*>(key_id), key_id_size),
           counter_block_str,
           data_offset,
           std::vector<SubsampleEntry>())));
   return encrypted_buffer;
 }
@@ skipping 370 matching lines @@
   scoped_refptr<DecoderBuffer> encrypted_data = CreateSubsampleEncryptedBuffer(
       kSubsampleData, arraysize(kSubsampleData),
       kSubsampleKeyId, arraysize(kSubsampleKeyId),
       kSubsampleIv, arraysize(kSubsampleIv),
       0,
       entries);
   ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToFail(encrypted_data));
 }
 
 }  // namespace media