Index: media/webm/webm_cluster_parser.cc |
=================================================================== |
--- media/webm/webm_cluster_parser.cc (revision 149456) |
+++ media/webm/webm_cluster_parser.cc (working copy) |
@@ -14,11 +14,20 @@ |
// 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. |
-// Returns a string of kDecryptionKeySize bytes. |
-static std::string GenerateCounterBlock(uint64 iv) { |
- std::string counter_block(reinterpret_cast<char*>(&iv), sizeof(iv)); |
- counter_block.append(DecryptConfig::kDecryptionKeySize - sizeof(iv), 0); |
- return counter_block; |
+// Always returns a valid pointer to a buffer of kDecryptionKeySize bytes. |
+static scoped_array<uint8> GenerateCounterBlock(uint64 iv) { |
+ scoped_array<uint8> counter_block_data( |
+ new uint8[DecryptConfig::kDecryptionKeySize]); |
+ |
+ // Set the IV. |
+ memcpy(counter_block_data.get(), &iv, sizeof(iv)); |
+ |
+ // Set block counter to all 0's. |
+ memset(counter_block_data.get() + sizeof(iv), |
+ 0, |
+ DecryptConfig::kDecryptionKeySize - sizeof(iv)); |
+ |
+ return counter_block_data.Pass(); |
} |
WebMClusterParser::WebMClusterParser(int64 timecode_scale, |
@@ -211,46 +220,34 @@ |
// Every encrypted Block has an HMAC and IV prepended to it. Current encrypted |
// WebM request for comments specification is here |
// http://wiki.webmproject.org/encryption/webm-encryption-rfc |
- bool is_track_encrypted = track_num == video_.track_num() && |
- video_encryption_key_id_.get(); |
+ bool encrypted = track_num == video_.track_num() && |
+ video_encryption_key_id_.get(); |
+ // If encrypted skip past the HMAC. Encrypted buffers must include the IV and |
+ // the encrypted frame because the decryptor will verify this data before |
+ // decryption. The HMAC and IV will be copied into DecryptConfig. |
+ int offset = (encrypted) ? kWebMHmacSize : 0; |
- // If stream is encrypted skip past the HMAC. Encrypted buffers must include |
- // the signal byte, the IV (if frame is encrypted) and |
- // the frame because the decryptor will verify this data before decryption. |
- // The HMAC and IV will be copied into DecryptConfig. |
- int offset = (is_track_encrypted) ? kWebMHmacSize : 0; |
- |
// The first bit of the flags is set when the block contains only keyframes. |
// http://www.matroska.org/technical/specs/index.html |
bool is_keyframe = (flags & 0x80) != 0; |
scoped_refptr<StreamParserBuffer> buffer = |
StreamParserBuffer::CopyFrom(data + offset, size - offset, is_keyframe); |
- if (is_track_encrypted) { |
- uint8 signal_byte = data[kWebMHmacSize]; |
- int data_offset = sizeof(signal_byte); |
+ if (encrypted) { |
+ uint64 network_iv; |
+ memcpy(&network_iv, data + kWebMHmacSize, sizeof(network_iv)); |
+ const uint64 iv = base::NetToHost64(network_iv); |
- // Setting the DecryptConfig object of the buffer while leaving the |
- // initialization vector empty will tell the decryptor that the frame is |
- // unencrypted but integrity should still be checked. |
- std::string counter_block; |
- |
- if (signal_byte & kWebMFlagEncryptedFrame) { |
- uint64 network_iv; |
- memcpy(&network_iv, data + kWebMHmacSize + data_offset, |
- sizeof(network_iv)); |
- const uint64 iv = base::NetToHost64(network_iv); |
- counter_block = GenerateCounterBlock(iv); |
- data_offset += sizeof(iv); |
- } |
- |
+ scoped_array<uint8> counter_block(GenerateCounterBlock(iv)); |
buffer->SetDecryptConfig(scoped_ptr<DecryptConfig>(new DecryptConfig( |
std::string( |
reinterpret_cast<const char*>(video_encryption_key_id_.get()), |
video_encryption_key_id_size_), |
- counter_block, |
+ std::string( |
+ reinterpret_cast<const char*>(counter_block.get()), |
+ DecryptConfig::kDecryptionKeySize), |
std::string(reinterpret_cast<const char*>(data), kWebMHmacSize), |
- data_offset, |
+ sizeof(iv), |
std::vector<SubsampleEntry>()))); |
} |