shaka-packager/packager/media/base/playready_pssh_generator.cc

170 lines
6.5 KiB
C++

// 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/base/playready_pssh_generator.h"
#include <openssl/aes.h>
#include <algorithm>
#include <memory>
#include <set>
#include <vector>
#include "packager/base/base64.h"
#include "packager/base/logging.h"
#include "packager/base/strings/string_number_conversions.h"
#include "packager/base/strings/string_util.h"
#include "packager/media/base/buffer_writer.h"
#include "packager/media/base/http_key_fetcher.h"
#include "packager/media/base/key_source.h"
#include "packager/media/base/playready_key_source.h"
namespace shaka {
namespace media {
namespace {
const std::string kPlayHeaderObject_4_1 =
"<WRMHEADER "
"xmlns=\"http://schemas.microsoft.com/DRM/2007/03/PlayReadyHeader\" "
"version=\"4.1.0.0\"><DATA><PROTECTINFO>"
"<KID VALUE=\"$0\" ALGID=\"AESCTR\" CHECKSUM=\"$1\"></KID></PROTECTINFO>"
"</DATA></WRMHEADER>";
const std::string kPlayHeaderObject_4_0 =
"<WRMHEADER "
"xmlns=\"http://schemas.microsoft.com/DRM/2007/03/PlayReadyHeader\" "
"version=\"4.0.0.0\"><DATA><PROTECTINFO><KEYLEN>16</KEYLEN>"
"<ALGID>AESCTR</ALGID></PROTECTINFO><KID>$0</KID><CHECKSUM>$1</CHECKSUM>"
"</DATA></WRMHEADER>";
// Converts the key_id's endianness.
std::vector<uint8_t> ConvertGuidEndianness(const std::vector<uint8_t>& input) {
std::vector<uint8_t> output = input;
if (output.size() > 7) { // Defensive check.
output[0] = input[3];
output[1] = input[2];
output[2] = input[1];
output[3] = input[0];
output[4] = input[5];
output[5] = input[4];
output[6] = input[7];
output[7] = input[6];
// 8-15 are an array of bytes with no endianness.
}
return output;
}
// Generates the data section of a PlayReady PSSH.
// PlayReady PSSH Data is a PlayReady Header Object.
// Format is outlined in the following document.
// http://download.microsoft.com/download/2/3/8/238F67D9-1B8B-48D3-AB83-9C00112268B2/PlayReady%20Header%20Object%202015-08-13-FINAL-CL.PDF
Status GeneratePlayReadyPsshData(const std::vector<uint8_t>& key_id,
const std::vector<uint8_t>& key,
std::vector<uint8_t>* output) {
CHECK(output);
std::vector<uint8_t> key_id_converted = ConvertGuidEndianness(key_id);
std::vector<uint8_t> encrypted_key_id(key_id_converted.size());
std::unique_ptr<AES_KEY> aes_key(new AES_KEY);
CHECK_EQ(AES_set_encrypt_key(key.data(), key.size() * 8, aes_key.get()), 0);
AES_ecb_encrypt(key_id_converted.data(), encrypted_key_id.data(),
aes_key.get(), AES_ENCRYPT);
std::string checksum =
std::string(encrypted_key_id.begin(), encrypted_key_id.end())
.substr(0, 8);
std::string base64_checksum;
base::Base64Encode(checksum, &base64_checksum);
std::string base64_key_id;
base::Base64Encode(
std::string(key_id_converted.begin(), key_id_converted.end()),
&base64_key_id);
std::string playready_header = kPlayHeaderObject_4_0;
base::ReplaceFirstSubstringAfterOffset(&playready_header, 0, "$0",
base64_key_id);
base::ReplaceFirstSubstringAfterOffset(&playready_header, 0, "$1",
base64_checksum);
// Create a PlayReady Record.
// Outline in section '2.PlayReady Records' of
// 'PlayReady Header Object' document. Note data is in little endian format.
std::vector<uint16_t> record_value =
std::vector<uint16_t>(playready_header.begin(), playready_header.end());
shaka::media::BufferWriter writer_pr_record;
uint16_t record_type =
1; // Indicates that the record contains a rights management header.
uint16_t record_length = record_value.size() * 2;
writer_pr_record.AppendInt(static_cast<uint8_t>(record_type & 0xff));
writer_pr_record.AppendInt(static_cast<uint8_t>((record_type >> 8) & 0xff));
writer_pr_record.AppendInt(static_cast<uint8_t>(record_length & 0xff));
writer_pr_record.AppendInt(static_cast<uint8_t>((record_length >> 8) & 0xff));
for (auto record_item : record_value) {
writer_pr_record.AppendInt(static_cast<uint8_t>(record_item & 0xff));
writer_pr_record.AppendInt(static_cast<uint8_t>((record_item >> 8) & 0xff));
}
// Create the PlayReady Header object.
// Outline in section '1.PlayReady Header Objects' of
// 'PlayReady Header Object' document. Note data is in little endian format.
shaka::media::BufferWriter writer_pr_header_object;
uint32_t playready_header_length = writer_pr_record.Size() + 4 + 2;
uint16_t record_count = 1;
writer_pr_header_object.AppendInt(
static_cast<uint8_t>(playready_header_length & 0xff));
writer_pr_header_object.AppendInt(
static_cast<uint8_t>((playready_header_length >> 8) & 0xff));
writer_pr_header_object.AppendInt(
static_cast<uint8_t>((playready_header_length >> 16) & 0xff));
writer_pr_header_object.AppendInt(
static_cast<uint8_t>((playready_header_length >> 24) & 0xff));
writer_pr_header_object.AppendInt(static_cast<uint8_t>(record_count & 0xff));
writer_pr_header_object.AppendInt(
static_cast<uint8_t>((record_count >> 8) & 0xff));
writer_pr_header_object.AppendBuffer(writer_pr_record);
*output = std::vector<uint8_t>(
writer_pr_header_object.Buffer(),
writer_pr_header_object.Buffer() + writer_pr_header_object.Size());
return Status::OK;
}
} // namespace
PlayReadyPsshGenerator::PlayReadyPsshGenerator()
: system_id_(std::begin(kPlayReadySystemId), std::end(kPlayReadySystemId)) {
}
PlayReadyPsshGenerator::~PlayReadyPsshGenerator() {}
bool PlayReadyPsshGenerator::SupportMultipleKeys() {
return false;
}
uint8_t PlayReadyPsshGenerator::PsshBoxVersion() const {
return 1;
}
const std::vector<uint8_t>& PlayReadyPsshGenerator::SystemId() const {
return system_id_;
}
base::Optional<std::vector<uint8_t>>
PlayReadyPsshGenerator::GeneratePsshDataFromKeyIdAndKey(
const std::vector<uint8_t>& key_id,
const std::vector<uint8_t>& key) const {
std::vector<uint8_t> pssh_data;
Status status = GeneratePlayReadyPsshData(key_id, key, &pssh_data);
if (!status.ok()) {
LOG(ERROR) << status.ToString();
return base::nullopt;
}
return pssh_data;
}
base::Optional<std::vector<uint8_t>>
PlayReadyPsshGenerator::GeneratePsshDataFromKeyIds(
const std::vector<std::vector<uint8_t>>& key_ids) const {
NOTIMPLEMENTED();
return base::nullopt;
}
} // namespace media
} // namespace shaka