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shaka-packager/packager/media/crypto/encryption_handler.cc

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// Copyright 2017 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
#include "packager/media/crypto/encryption_handler.h"
#include <stddef.h>
#include <stdint.h>
#include <limits>
#include "packager/media/base/aes_encryptor.h"
#include "packager/media/base/aes_pattern_cryptor.h"
#include "packager/media/base/key_source.h"
#include "packager/media/base/media_sample.h"
#include "packager/media/base/audio_stream_info.h"
#include "packager/media/base/video_stream_info.h"
#include "packager/media/codecs/video_slice_header_parser.h"
#include "packager/media/codecs/vp8_parser.h"
#include "packager/media/codecs/vp9_parser.h"
namespace shaka {
namespace media {
namespace {
const size_t kCencBlockSize = 16u;
// The encryption handler only supports a single output.
const size_t kStreamIndex = 0;
// The default KID for key rotation is all 0s.
const uint8_t kKeyRotationDefaultKeyId[] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
};
// Adds one or more subsamples to |*decrypt_config|. This may add more than one
// if one of the values overflows the integer in the subsample.
void AddSubsample(uint64_t clear_bytes,
uint64_t cipher_bytes,
DecryptConfig* decrypt_config) {
CHECK_LT(cipher_bytes, std::numeric_limits<uint32_t>::max());
const uint64_t kUInt16Max = std::numeric_limits<uint16_t>::max();
while (clear_bytes > kUInt16Max) {
decrypt_config->AddSubsample(kUInt16Max, 0);
clear_bytes -= kUInt16Max;
}
if (clear_bytes > 0 || cipher_bytes > 0)
decrypt_config->AddSubsample(clear_bytes, cipher_bytes);
}
uint8_t GetNaluLengthSize(const StreamInfo& stream_info) {
if (stream_info.stream_type() != kStreamVideo)
return 0;
const VideoStreamInfo& video_stream_info =
static_cast<const VideoStreamInfo&>(stream_info);
return video_stream_info.nalu_length_size();
}
std::string GetStreamLabelForEncryption(
const StreamInfo& stream_info,
const std::function<std::string(
const EncryptionParams::EncryptedStreamAttributes& stream_attributes)>&
stream_label_func) {
EncryptionParams::EncryptedStreamAttributes stream_attributes;
if (stream_info.stream_type() == kStreamAudio) {
stream_attributes.stream_type =
EncryptionParams::EncryptedStreamAttributes::kAudio;
} else if (stream_info.stream_type() == kStreamVideo) {
const VideoStreamInfo& video_stream_info =
static_cast<const VideoStreamInfo&>(stream_info);
stream_attributes.stream_type =
EncryptionParams::EncryptedStreamAttributes::kVideo;
stream_attributes.oneof.video.width = video_stream_info.width();
stream_attributes.oneof.video.height = video_stream_info.height();
}
return stream_label_func(stream_attributes);
}
} // namespace
EncryptionHandler::EncryptionHandler(const EncryptionParams& encryption_params,
KeySource* key_source)
: encryption_params_(encryption_params),
protection_scheme_(
static_cast<FourCC>(encryption_params.protection_scheme)),
key_source_(key_source) {}
EncryptionHandler::~EncryptionHandler() {}
Status EncryptionHandler::InitializeInternal() {
if (!encryption_params_.stream_label_func) {
return Status(error::INVALID_ARGUMENT, "Stream label function not set.");
}
if (num_input_streams() != 1 || next_output_stream_index() != 1) {
return Status(error::INVALID_ARGUMENT,
"Expects exactly one input and output.");
}
return Status::OK;
}
Status EncryptionHandler::Process(std::unique_ptr<StreamData> stream_data) {
switch (stream_data->stream_data_type) {
case StreamDataType::kStreamInfo:
return ProcessStreamInfo(*stream_data->stream_info);
case StreamDataType::kSegmentInfo: {
std::shared_ptr<SegmentInfo> segment_info(new SegmentInfo(
*stream_data->segment_info));
segment_info->is_encrypted = remaining_clear_lead_ <= 0;
const bool key_rotation_enabled = crypto_period_duration_ != 0;
if (key_rotation_enabled)
segment_info->key_rotation_encryption_config = encryption_config_;
if (!segment_info->is_subsegment) {
if (key_rotation_enabled)
check_new_crypto_period_ = true;
if (remaining_clear_lead_ > 0)
remaining_clear_lead_ -= segment_info->duration;
}
return DispatchSegmentInfo(kStreamIndex, segment_info);
}
case StreamDataType::kMediaSample:
return ProcessMediaSample(std::move(stream_data->media_sample));
default:
VLOG(3) << "Stream data type "
<< static_cast<int>(stream_data->stream_data_type) << " ignored.";
return Dispatch(std::move(stream_data));
}
}
Status EncryptionHandler::ProcessStreamInfo(const StreamInfo& clear_info) {
if (clear_info.is_encrypted()) {
return Status(error::INVALID_ARGUMENT,
"Input stream is already encrypted.");
}
DCHECK_NE(kStreamUnknown, clear_info.stream_type());
DCHECK_NE(kStreamText, clear_info.stream_type());
std::shared_ptr<StreamInfo> stream_info = clear_info.Clone();
remaining_clear_lead_ =
encryption_params_.clear_lead_in_seconds * stream_info->time_scale();
crypto_period_duration_ =
encryption_params_.crypto_period_duration_in_seconds *
stream_info->time_scale();
codec_ = stream_info->codec();
nalu_length_size_ = GetNaluLengthSize(*stream_info);
stream_label_ = GetStreamLabelForEncryption(
*stream_info, encryption_params_.stream_label_func);
switch (codec_) {
case kCodecVP9:
if (encryption_params_.vp9_subsample_encryption)
vpx_parser_.reset(new VP9Parser);
break;
case kCodecH264:
header_parser_.reset(new H264VideoSliceHeaderParser);
break;
case kCodecH265:
header_parser_.reset(new H265VideoSliceHeaderParser);
break;
default:
// Other codecs should have nalu length size == 0.
if (nalu_length_size_ > 0) {
LOG(WARNING) << "Unknown video codec '" << codec_ << "'";
return Status(error::ENCRYPTION_FAILURE, "Unknown video codec.");
}
}
if (header_parser_) {
CHECK_NE(nalu_length_size_, 0u) << "AnnexB stream is not supported yet";
if (!header_parser_->Initialize(stream_info->codec_config())) {
return Status(error::ENCRYPTION_FAILURE,
"Fail to read SPS and PPS data.");
}
}
Status status = SetupProtectionPattern(stream_info->stream_type());
if (!status.ok())
return status;
EncryptionKey encryption_key;
const bool key_rotation_enabled = crypto_period_duration_ != 0;
if (key_rotation_enabled) {
check_new_crypto_period_ = true;
// Setup dummy key id and key to signal encryption for key rotation.
encryption_key.key_id.assign(
kKeyRotationDefaultKeyId,
kKeyRotationDefaultKeyId + sizeof(kKeyRotationDefaultKeyId));
// The key is not really used to encrypt any data. It is there just for
// convenience.
encryption_key.key = encryption_key.key_id;
} else {
status = key_source_->GetKey(stream_label_, &encryption_key);
if (!status.ok())
return status;
}
if (!CreateEncryptor(encryption_key))
return Status(error::ENCRYPTION_FAILURE, "Failed to create encryptor");
stream_info->set_is_encrypted(true);
stream_info->set_has_clear_lead(encryption_params_.clear_lead_in_seconds > 0);
stream_info->set_encryption_config(*encryption_config_);
return DispatchStreamInfo(kStreamIndex, stream_info);
}
Status EncryptionHandler::ProcessMediaSample(
std::shared_ptr<const MediaSample> clear_sample) {
DCHECK(clear_sample);
// We need to parse the frame (which also updates the vpx parser) even if the
// frame is not encrypted as the next (encrypted) frame may be dependent on
// this clear frame.
std::vector<VPxFrameInfo> vpx_frames;
if (vpx_parser_ && !vpx_parser_->Parse(clear_sample->data(),
clear_sample->data_size(),
&vpx_frames)) {
return Status(error::ENCRYPTION_FAILURE, "Failed to parse vpx frame.");
}
// Need to setup the encryptor for new segments even if this segment does not
// need to be encrypted, so we can signal encryption metadata earlier to
// allows clients to prefetch the keys.
if (check_new_crypto_period_) {
const int64_t current_crypto_period_index =
clear_sample->dts() / crypto_period_duration_;
if (current_crypto_period_index != prev_crypto_period_index_) {
EncryptionKey encryption_key;
Status status = key_source_->GetCryptoPeriodKey(
current_crypto_period_index, stream_label_, &encryption_key);
if (!status.ok())
return status;
if (!CreateEncryptor(encryption_key))
return Status(error::ENCRYPTION_FAILURE, "Failed to create encryptor");
prev_crypto_period_index_ = current_crypto_period_index;
}
check_new_crypto_period_ = false;
}
// Since there is no encryption needed right now, send the clear copy
// downstream so we can save the costs of copying it.
if (remaining_clear_lead_ > 0) {
return DispatchMediaSample(kStreamIndex, std::move(clear_sample));
}
std::unique_ptr<DecryptConfig> decrypt_config(new DecryptConfig(
encryption_config_->key_id,
encryptor_->iv(),
std::vector<SubsampleEntry>(),
protection_scheme_,
crypt_byte_block_,
skip_byte_block_));
// Now that we know that this sample must be encrypted, make a copy of
// the sample first so that all the encryption operations can be done
// in-place.
std::shared_ptr<MediaSample> cipher_sample =
MediaSample::CopyFrom(*clear_sample);
Status result;
if (vpx_parser_) {
if (EncryptVpxFrame(vpx_frames,
cipher_sample->writable_data(),
cipher_sample->data_size(),
decrypt_config.get())) {
DCHECK_EQ(decrypt_config->GetTotalSizeOfSubsamples(),
cipher_sample->data_size());
} else {
result = Status(
error::ENCRYPTION_FAILURE,
"Failed to encrypt VPX frame.");
}
} else if (header_parser_) {
if (EncryptNalFrame(cipher_sample->writable_data(),
cipher_sample->data_size(),
decrypt_config.get())) {
DCHECK_EQ(decrypt_config->GetTotalSizeOfSubsamples(),
cipher_sample->data_size());
} else {
result = Status(
error::ENCRYPTION_FAILURE,
"Failed to encrypt NAL frame.");
}
} else if (cipher_sample->data_size() > leading_clear_bytes_size_) {
EncryptBytes(
cipher_sample->writable_data() + leading_clear_bytes_size_,
cipher_sample->data_size() - leading_clear_bytes_size_);
}
if (!result.ok()) {
return result;
}
encryptor_->UpdateIv();
// Finish initializing the sample before sending it downstream. We must
// wait until now to finish the initialization as we will loose access to
// |decrypt_config| once we set it.
cipher_sample->set_is_encrypted(true);
cipher_sample->set_decrypt_config(std::move(decrypt_config));
return DispatchMediaSample(kStreamIndex, std::move(cipher_sample));
}
Status EncryptionHandler::SetupProtectionPattern(StreamType stream_type) {
switch (protection_scheme_) {
case kAppleSampleAesProtectionScheme: {
const size_t kH264LeadingClearBytesSize = 32u;
const size_t kSmallNalUnitSize = 32u + 16u;
const size_t kAudioLeadingClearBytesSize = 16u;
switch (codec_) {
case kCodecH264:
// Apple Sample AES uses 1:9 pattern for video.
crypt_byte_block_ = 1u;
skip_byte_block_ = 9u;
leading_clear_bytes_size_ = kH264LeadingClearBytesSize;
min_protected_data_size_ = kSmallNalUnitSize + 1u;
break;
case kCodecAAC:
FALLTHROUGH_INTENDED;
case kCodecAC3:
// Audio is whole sample encrypted. We could not use a
// crypto_byte_block_ of 1 here as if there is one crypto block
// remaining, it need not be encrypted for video but it needs to be
// encrypted for audio.
crypt_byte_block_ = 0u;
skip_byte_block_ = 0u;
leading_clear_bytes_size_ = kAudioLeadingClearBytesSize;
min_protected_data_size_ = leading_clear_bytes_size_ + 1u;
break;
default:
return Status(error::ENCRYPTION_FAILURE,
"Only AAC/AC3 and H264 are supported in Sample AES.");
}
break;
}
case FOURCC_cbcs:
FALLTHROUGH_INTENDED;
case FOURCC_cens:
if (stream_type == kStreamVideo) {
// Use 1:9 pattern for video.
crypt_byte_block_ = 1u;
skip_byte_block_ = 9u;
} else {
// Tracks other than video are protected using whole-block full-sample
// encryption, which is essentially a pattern of 1:0. Note that this may
// not be the same as the non-pattern based encryption counterparts,
// e.g. in 'cens' for full sample encryption, the whole sample is
// encrypted up to the last 16-byte boundary, see 23001-7:2016(E) 9.7;
// while in 'cenc' for full sample encryption, the last partial 16-byte
// block is also encrypted, see 23001-7:2016(E) 9.4.2. Another
// difference is the use of constant iv.
crypt_byte_block_ = 1u;
skip_byte_block_ = 0u;
}
break;
default:
// Not using pattern encryption.
crypt_byte_block_ = 0u;
skip_byte_block_ = 0u;
}
return Status::OK;
}
bool EncryptionHandler::CreateEncryptor(const EncryptionKey& encryption_key) {
std::unique_ptr<AesCryptor> encryptor;
switch (protection_scheme_) {
case FOURCC_cenc:
encryptor.reset(new AesCtrEncryptor);
break;
case FOURCC_cbc1:
encryptor.reset(new AesCbcEncryptor(kNoPadding));
break;
case FOURCC_cens:
encryptor.reset(new AesPatternCryptor(
crypt_byte_block_, skip_byte_block_,
AesPatternCryptor::kEncryptIfCryptByteBlockRemaining,
AesCryptor::kDontUseConstantIv,
std::unique_ptr<AesCryptor>(new AesCtrEncryptor())));
break;
case FOURCC_cbcs:
encryptor.reset(new AesPatternCryptor(
crypt_byte_block_, skip_byte_block_,
AesPatternCryptor::kEncryptIfCryptByteBlockRemaining,
AesCryptor::kUseConstantIv,
std::unique_ptr<AesCryptor>(new AesCbcEncryptor(kNoPadding))));
break;
case kAppleSampleAesProtectionScheme:
if (crypt_byte_block_ == 0 && skip_byte_block_ == 0) {
encryptor.reset(
new AesCbcEncryptor(kNoPadding, AesCryptor::kUseConstantIv));
} else {
encryptor.reset(new AesPatternCryptor(
crypt_byte_block_, skip_byte_block_,
AesPatternCryptor::kSkipIfCryptByteBlockRemaining,
AesCryptor::kUseConstantIv,
std::unique_ptr<AesCryptor>(new AesCbcEncryptor(kNoPadding))));
}
break;
default:
LOG(ERROR) << "Unsupported protection scheme.";
return false;
}
std::vector<uint8_t> iv = encryption_key.iv;
if (iv.empty()) {
if (!AesCryptor::GenerateRandomIv(protection_scheme_, &iv)) {
LOG(ERROR) << "Failed to generate random iv.";
return false;
}
}
const bool initialized =
encryptor->InitializeWithIv(encryption_key.key, iv);
encryptor_ = std::move(encryptor);
encryption_config_.reset(new EncryptionConfig);
encryption_config_->protection_scheme = protection_scheme_;
encryption_config_->crypt_byte_block = crypt_byte_block_;
encryption_config_->skip_byte_block = skip_byte_block_;
if (encryptor_->use_constant_iv()) {
encryption_config_->per_sample_iv_size = 0;
encryption_config_->constant_iv = iv;
} else {
encryption_config_->per_sample_iv_size = static_cast<uint8_t>(iv.size());
}
encryption_config_->key_id = encryption_key.key_id;
encryption_config_->key_system_info = encryption_key.key_system_info;
return initialized;
}
bool EncryptionHandler::EncryptVpxFrame(
const std::vector<VPxFrameInfo>& vpx_frames,
uint8_t* source,
size_t source_size,
DecryptConfig* decrypt_config) {
uint8_t* data = source;
for (const VPxFrameInfo& frame : vpx_frames) {
uint16_t clear_bytes =
static_cast<uint16_t>(frame.uncompressed_header_size);
uint32_t cipher_bytes = static_cast<uint32_t>(
frame.frame_size - frame.uncompressed_header_size);
// "VP Codec ISO Media File Format Binding" document requires that the
// encrypted bytes of each frame within the superframe must be block
// aligned so that the counter state can be computed for each frame
// within the superframe.
// ISO/IEC 23001-7:2016 10.2 'cbc1' 10.3 'cens'
// The BytesOfProtectedData size SHALL be a multiple of 16 bytes to
// avoid partial blocks in Subsamples.
// For consistency, apply block alignment to all frames.
const uint16_t misalign_bytes = cipher_bytes % kCencBlockSize;
clear_bytes += misalign_bytes;
cipher_bytes -= misalign_bytes;
decrypt_config->AddSubsample(clear_bytes, cipher_bytes);
if (cipher_bytes > 0)
EncryptBytes(data + clear_bytes, cipher_bytes);
data += frame.frame_size;
}
// Add subsample for the superframe index if exists.
const bool is_superframe = vpx_frames.size() > 1;
if (is_superframe) {
size_t index_size = source + source_size - data;
DCHECK_LE(index_size, 2 + vpx_frames.size() * 4);
DCHECK_GE(index_size, 2 + vpx_frames.size() * 1);
uint16_t clear_bytes = static_cast<uint16_t>(index_size);
uint32_t cipher_bytes = 0;
decrypt_config->AddSubsample(clear_bytes, cipher_bytes);
}
return true;
}
bool EncryptionHandler::EncryptNalFrame(uint8_t* data,
size_t data_length,
DecryptConfig* decrypt_config) {
DCHECK_NE(nalu_length_size_, 0u);
DCHECK(header_parser_);
const Nalu::CodecType nalu_type =
(codec_ == kCodecH265) ? Nalu::kH265 : Nalu::kH264;
NaluReader reader(nalu_type, nalu_length_size_, data, data_length);
// Store the current length of clear data. This is used to squash
// multiple unencrypted NAL units into fewer subsample entries.
uint64_t accumulated_clear_bytes = 0;
Nalu nalu;
NaluReader::Result result;
while ((result = reader.Advance(&nalu)) == NaluReader::kOk) {
const uint64_t nalu_total_size = nalu.header_size() + nalu.payload_size();
if (nalu.is_video_slice() && nalu_total_size >= min_protected_data_size_) {
uint64_t current_clear_bytes = leading_clear_bytes_size_;
if (current_clear_bytes == 0) {
// For video-slice NAL units, encrypt the video slice. This skips
// the frame header.
const int64_t video_slice_header_size =
header_parser_->GetHeaderSize(nalu);
if (video_slice_header_size < 0) {
LOG(ERROR) << "Failed to read slice header.";
return false;
}
current_clear_bytes = nalu.header_size() + video_slice_header_size;
}
uint64_t cipher_bytes = nalu_total_size - current_clear_bytes;
// ISO/IEC 23001-7:2016 10.2 'cbc1' 10.3 'cens'
// The BytesOfProtectedData size SHALL be a multiple of 16 bytes to
// avoid partial blocks in Subsamples.
// CMAF requires 'cenc' scheme BytesOfProtectedData SHALL be a multiple
// of 16 bytes; while 'cbcs' scheme BytesOfProtectedData SHALL start on
// the first byte of video data following the slice header.
if (protection_scheme_ == FOURCC_cbc1 ||
protection_scheme_ == FOURCC_cens ||
protection_scheme_ == FOURCC_cenc) {
const uint16_t misalign_bytes = cipher_bytes % kCencBlockSize;
current_clear_bytes += misalign_bytes;
cipher_bytes -= misalign_bytes;
}
const uint8_t* nalu_data = nalu.data() + current_clear_bytes;
EncryptBytes(const_cast<uint8_t*>(nalu_data), cipher_bytes);
AddSubsample(
accumulated_clear_bytes + nalu_length_size_ + current_clear_bytes,
cipher_bytes, decrypt_config);
accumulated_clear_bytes = 0;
} else {
// For non-video-slice or small NAL units, don't encrypt.
accumulated_clear_bytes += nalu_length_size_ + nalu_total_size;
}
}
if (result != NaluReader::kEOStream) {
LOG(ERROR) << "Failed to parse NAL units.";
return false;
}
AddSubsample(accumulated_clear_bytes, 0, decrypt_config);
return true;
}
void EncryptionHandler::EncryptBytes(uint8_t* data, size_t size) {
DCHECK(data);
DCHECK(encryptor_);
CHECK(encryptor_->Crypt(data, size, data));
}
void EncryptionHandler::InjectVpxParserForTesting(
std::unique_ptr<VPxParser> vpx_parser) {
vpx_parser_ = std::move(vpx_parser);
}
void EncryptionHandler::InjectVideoSliceHeaderParserForTesting(
std::unique_ptr<VideoSliceHeaderParser> header_parser) {
header_parser_ = std::move(header_parser);
}
} // namespace media
} // namespace shaka
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