Index: media/webm/webm_cluster_parser.cc |
diff --git a/media/webm/webm_cluster_parser.cc b/media/webm/webm_cluster_parser.cc |
index e9ef93e3fb14c8bd29197f0e826dcff6c9bf25a1..f5664d71799431134b29db3d0b3d4524f19cac55 100644 |
--- a/media/webm/webm_cluster_parser.cc |
+++ b/media/webm/webm_cluster_parser.cc |
@@ -14,20 +14,18 @@ namespace media { |
// 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. |
-// 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]); |
+// Returns a string of kDecryptionKeySize bytes. |
+static std::string GenerateCounterBlock(uint64 iv) { |
+ char counter_block_data[DecryptConfig::kDecryptionKeySize]; |
// Set the IV. |
- memcpy(counter_block_data.get(), &iv, sizeof(iv)); |
+ memcpy(counter_block_data, &iv, sizeof(iv)); |
// Set block counter to all 0's. |
- memset(counter_block_data.get() + sizeof(iv), |
- 0, |
+ memset(counter_block_data + sizeof(iv), 0, |
DecryptConfig::kDecryptionKeySize - sizeof(iv)); |
- return counter_block_data.Pass(); |
+ return std::string(counter_block_data, DecryptConfig::kDecryptionKeySize); |
xhwang
2012/08/01 04:38:23
Can we do something like this:
std::string counter
fgalligan1
2012/08/01 15:07:38
I changed to this:
std::string counter_block(reint
|
} |
WebMClusterParser::WebMClusterParser(int64 timecode_scale, |
@@ -220,12 +218,14 @@ bool WebMClusterParser::OnBlock(int track_num, int timecode, |
// 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 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; |
+ bool is_track_encrypted = track_num == video_.track_num() && |
+ video_encryption_key_id_.get(); |
+ |
+ // 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 |
@@ -233,21 +233,31 @@ bool WebMClusterParser::OnBlock(int track_num, int timecode, |
scoped_refptr<StreamParserBuffer> buffer = |
StreamParserBuffer::CopyFrom(data + offset, size - offset, is_keyframe); |
- if (encrypted) { |
- uint64 network_iv; |
- memcpy(&network_iv, data + kWebMHmacSize, sizeof(network_iv)); |
- const uint64 iv = base::NetToHost64(network_iv); |
+ if (is_track_encrypted) { |
+ uint8 signal_byte = data[kWebMHmacSize]; |
+ int data_offset = sizeof(signal_byte); |
+ |
+ // 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_), |
- std::string( |
- reinterpret_cast<const char*>(counter_block.get()), |
- DecryptConfig::kDecryptionKeySize), |
+ counter_block, |
std::string(reinterpret_cast<const char*>(data), kWebMHmacSize), |
- sizeof(iv), |
+ data_offset, |
std::vector<SubsampleEntry>()))); |
} |