15d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles)// Copyright 2014 The Chromium Authors. All rights reserved. 22a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)// Use of this source code is governed by a BSD-style license that can be 32a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)// found in the LICENSE file. 42a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 55d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles)#include "media/formats/webm/webm_crypto_helpers.h" 62a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 72a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)#include "base/logging.h" 82a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)#include "base/sys_byteorder.h" 92a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)#include "media/base/decrypt_config.h" 105d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles)#include "media/formats/webm/webm_constants.h" 112a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 122a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)namespace media { 132a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)namespace { 142a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 152a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)// Generates a 16 byte CTR counter block. The CTR counter block format is a 162a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)// CTR IV appended with a CTR block counter. |iv| is an 8 byte CTR IV. 172a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)// |iv_size| is the size of |iv| in btyes. Returns a string of 182a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)// kDecryptionKeySize bytes. 192a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)std::string GenerateWebMCounterBlock(const uint8* iv, int iv_size) { 202a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) std::string counter_block(reinterpret_cast<const char*>(iv), iv_size); 212a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) counter_block.append(DecryptConfig::kDecryptionKeySize - iv_size, 0); 222a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) return counter_block; 232a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)} 242a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 252a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)} // namespace anonymous 262a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 275d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles)bool WebMCreateDecryptConfig(const uint8* data, int data_size, 285d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) const uint8* key_id, int key_id_size, 295d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) scoped_ptr<DecryptConfig>* decrypt_config, 305d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) int* data_offset) { 312a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) if (data_size < kWebMSignalByteSize) { 322a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) DVLOG(1) << "Got a block from an encrypted stream with no data."; 335d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) return false; 342a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) } 352a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 362a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) uint8 signal_byte = data[0]; 372a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) int frame_offset = sizeof(signal_byte); 382a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 392a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) // Setting the DecryptConfig object of the buffer while leaving the 402a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) // initialization vector empty will tell the decryptor that the frame is 412a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) // unencrypted. 422a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) std::string counter_block; 432a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 442a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) if (signal_byte & kWebMFlagEncryptedFrame) { 452a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) if (data_size < kWebMSignalByteSize + kWebMIvSize) { 462a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) DVLOG(1) << "Got an encrypted block with not enough data " << data_size; 475d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) return false; 482a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) } 492a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) counter_block = GenerateWebMCounterBlock(data + frame_offset, kWebMIvSize); 502a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) frame_offset += kWebMIvSize; 512a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) } 522a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 535d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) decrypt_config->reset(new DecryptConfig( 542a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) std::string(reinterpret_cast<const char*>(key_id), key_id_size), 552a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) counter_block, 562a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) std::vector<SubsampleEntry>())); 575d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) *data_offset = frame_offset; 585d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) 595d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) return true; 602a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)} 612a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) 622a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)} // namespace media 63