161 lines
5.7 KiB
C++
161 lines
5.7 KiB
C++
// Copyright 2016 Google Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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#include "packager/media/base/raw_key_source.h"
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#include <algorithm>
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#include "packager/base/logging.h"
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#include "packager/base/strings/string_number_conversions.h"
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namespace {
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const char kEmptyDrmLabel[] = "";
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} // namespace
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namespace shaka {
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namespace media {
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RawKeySource::~RawKeySource() {}
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Status RawKeySource::FetchKeys(EmeInitDataType init_data_type,
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const std::vector<uint8_t>& init_data) {
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// Do nothing for raw key encryption/decryption.
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return Status::OK;
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}
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Status RawKeySource::GetKey(const std::string& stream_label,
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EncryptionKey* key) {
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DCHECK(key);
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// Try to find the key with label |stream_label|. If it is not available,
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// fall back to the default empty label if it is available.
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auto iter = encryption_key_map_.find(stream_label);
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if (iter == encryption_key_map_.end()) {
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iter = encryption_key_map_.find(kEmptyDrmLabel);
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if (iter == encryption_key_map_.end()) {
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return Status(error::NOT_FOUND,
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"Key for '" + stream_label + "' was not found.");
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}
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}
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*key = *iter->second;
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return Status::OK;
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}
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Status RawKeySource::GetKey(const std::vector<uint8_t>& key_id,
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EncryptionKey* key) {
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DCHECK(key);
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for (const auto& pair : encryption_key_map_) {
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if (pair.second->key_id == key_id) {
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*key = *pair.second;
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return Status::OK;
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}
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}
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return Status(error::INTERNAL_ERROR,
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"Key for key_id=" + base::HexEncode(&key_id[0], key_id.size()) +
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" was not found.");
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}
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Status RawKeySource::GetCryptoPeriodKey(uint32_t crypto_period_index,
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const std::string& stream_label,
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EncryptionKey* key) {
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Status status = GetKey(stream_label, key);
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if (!status.ok())
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return status;
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// A naive key rotation algorithm is implemented here by left rotating the
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// key, key_id and pssh. Note that this implementation is only intended for
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// testing purpose. The actual key rotation algorithm can be much more
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// complicated.
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LOG(WARNING)
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<< "This naive key rotation algorithm should not be used in production.";
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std::rotate(key->key_id.begin(),
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key->key_id.begin() + (crypto_period_index % key->key_id.size()),
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key->key_id.end());
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std::rotate(key->key.begin(),
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key->key.begin() + (crypto_period_index % key->key.size()),
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key->key.end());
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for (auto& key_system : key->key_system_info) {
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std::vector<uint8_t> pssh_data = key_system.pssh_data();
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if (!pssh_data.empty()) {
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std::rotate(pssh_data.begin(),
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pssh_data.begin() + (crypto_period_index % pssh_data.size()),
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pssh_data.end());
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key_system.set_pssh_data(pssh_data);
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}
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// Rotate the key_ids in pssh as well if exists.
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// Save a local copy of the key ids before clearing the key ids in
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// |key_system|. The key ids will be updated and added back later.
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std::vector<std::vector<uint8_t>> key_ids_copy = key_system.key_ids();
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key_system.clear_key_ids();
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for (std::vector<uint8_t>& key_id : key_ids_copy) {
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std::rotate(key_id.begin(),
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key_id.begin() + (crypto_period_index % key_id.size()),
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key_id.end());
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key_system.add_key_id(key_id);
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}
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}
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return Status::OK;
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}
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std::unique_ptr<RawKeySource> RawKeySource::Create(
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const RawKeyParams& raw_key) {
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std::vector<ProtectionSystemSpecificInfo> key_system_info;
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if (!raw_key.pssh.empty()) {
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if (!ProtectionSystemSpecificInfo::ParseBoxes(
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raw_key.pssh.data(), raw_key.pssh.size(), &key_system_info)) {
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LOG(ERROR) << "--pssh argument should be full PSSH boxes.";
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return std::unique_ptr<RawKeySource>();
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}
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} else {
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// If there aren't any PSSH boxes given, create one with the common system
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// ID.
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key_system_info.resize(1);
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for (const auto& entry : raw_key.key_map) {
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const RawKeyParams::KeyInfo& key_pair = entry.second;
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key_system_info.back().add_key_id(key_pair.key_id);
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}
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key_system_info.back().set_system_id(kCommonSystemId,
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arraysize(kCommonSystemId));
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key_system_info.back().set_pssh_box_version(1);
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}
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EncryptionKeyMap encryption_key_map;
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for (const auto& entry : raw_key.key_map) {
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const std::string& drm_label = entry.first;
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const RawKeyParams::KeyInfo& key_pair = entry.second;
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if (key_pair.key_id.size() != 16) {
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LOG(ERROR) << "Invalid key ID size '" << key_pair.key_id.size()
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<< "', must be 16 bytes.";
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return std::unique_ptr<RawKeySource>();
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}
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if (key_pair.key.size() != 16) {
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// CENC only supports AES-128, i.e. 16 bytes.
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LOG(ERROR) << "Invalid key size '" << key_pair.key.size()
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<< "', must be 16 bytes.";
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return std::unique_ptr<RawKeySource>();
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}
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std::unique_ptr<EncryptionKey> encryption_key(new EncryptionKey);
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encryption_key->key_id = key_pair.key_id;
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encryption_key->key = key_pair.key;
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encryption_key->iv = raw_key.iv;
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encryption_key->key_system_info = key_system_info;
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encryption_key_map[drm_label] = std::move(encryption_key);
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}
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return std::unique_ptr<RawKeySource>(
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new RawKeySource(std::move(encryption_key_map)));
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}
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RawKeySource::RawKeySource() {}
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RawKeySource::RawKeySource(EncryptionKeyMap&& encryption_key_map)
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: encryption_key_map_(std::move(encryption_key_map)) {}
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} // namespace media
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} // namespace shaka
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