1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
|
// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "media/cdm/aes_decryptor.h"
#include <stddef.h>
#include <list>
#include <utility>
#include <vector>
#include "base/logging.h"
#include "base/macros.h"
#include "base/stl_util.h"
#include "base/strings/string_number_conversions.h"
#include "crypto/encryptor.h"
#include "crypto/symmetric_key.h"
#include "media/base/audio_decoder_config.h"
#include "media/base/cdm_key_information.h"
#include "media/base/cdm_promise.h"
#include "media/base/decoder_buffer.h"
#include "media/base/decrypt_config.h"
#include "media/base/video_decoder_config.h"
#include "media/base/video_frame.h"
#include "media/cdm/json_web_key.h"
#if defined(USE_PROPRIETARY_CODECS)
#include "media/cdm/cenc_utils.h"
#endif
namespace media {
// Keeps track of the session IDs and DecryptionKeys. The keys are ordered by
// insertion time (last insertion is first). It takes ownership of the
// DecryptionKeys.
class AesDecryptor::SessionIdDecryptionKeyMap {
// Use a std::list to actually hold the data. Insertion is always done
// at the front, so the "latest" decryption key is always the first one
// in the list.
typedef std::list<std::pair<std::string, DecryptionKey*> > KeyList;
public:
SessionIdDecryptionKeyMap() {}
~SessionIdDecryptionKeyMap() { STLDeleteValues(&key_list_); }
// Replaces value if |session_id| is already present, or adds it if not.
// This |decryption_key| becomes the latest until another insertion or
// |session_id| is erased.
void Insert(const std::string& session_id,
scoped_ptr<DecryptionKey> decryption_key);
// Deletes the entry for |session_id| if present.
void Erase(const std::string& session_id);
// Returns whether the list is empty
bool Empty() const { return key_list_.empty(); }
// Returns the last inserted DecryptionKey.
DecryptionKey* LatestDecryptionKey() {
DCHECK(!key_list_.empty());
return key_list_.begin()->second;
}
bool Contains(const std::string& session_id) {
return Find(session_id) != key_list_.end();
}
private:
// Searches the list for an element with |session_id|.
KeyList::iterator Find(const std::string& session_id);
// Deletes the entry pointed to by |position|.
void Erase(KeyList::iterator position);
KeyList key_list_;
DISALLOW_COPY_AND_ASSIGN(SessionIdDecryptionKeyMap);
};
void AesDecryptor::SessionIdDecryptionKeyMap::Insert(
const std::string& session_id,
scoped_ptr<DecryptionKey> decryption_key) {
KeyList::iterator it = Find(session_id);
if (it != key_list_.end())
Erase(it);
DecryptionKey* raw_ptr = decryption_key.release();
key_list_.push_front(std::make_pair(session_id, raw_ptr));
}
void AesDecryptor::SessionIdDecryptionKeyMap::Erase(
const std::string& session_id) {
KeyList::iterator it = Find(session_id);
if (it == key_list_.end())
return;
Erase(it);
}
AesDecryptor::SessionIdDecryptionKeyMap::KeyList::iterator
AesDecryptor::SessionIdDecryptionKeyMap::Find(const std::string& session_id) {
for (KeyList::iterator it = key_list_.begin(); it != key_list_.end(); ++it) {
if (it->first == session_id)
return it;
}
return key_list_.end();
}
void AesDecryptor::SessionIdDecryptionKeyMap::Erase(
KeyList::iterator position) {
DCHECK(position->second);
delete position->second;
key_list_.erase(position);
}
uint32_t AesDecryptor::next_session_id_ = 1;
enum ClearBytesBufferSel {
kSrcContainsClearBytes,
kDstContainsClearBytes
};
static void CopySubsamples(const std::vector<SubsampleEntry>& subsamples,
const ClearBytesBufferSel sel,
const uint8_t* src,
uint8_t* dst) {
for (size_t i = 0; i < subsamples.size(); i++) {
const SubsampleEntry& subsample = subsamples[i];
if (sel == kSrcContainsClearBytes) {
src += subsample.clear_bytes;
} else {
dst += subsample.clear_bytes;
}
memcpy(dst, src, subsample.cypher_bytes);
src += subsample.cypher_bytes;
dst += subsample.cypher_bytes;
}
}
// Decrypts |input| using |key|. Returns a DecoderBuffer with the decrypted
// data if decryption succeeded or NULL if decryption failed.
static scoped_refptr<DecoderBuffer> DecryptData(const DecoderBuffer& input,
crypto::SymmetricKey* key) {
CHECK(input.data_size());
CHECK(input.decrypt_config());
CHECK(key);
crypto::Encryptor encryptor;
if (!encryptor.Init(key, crypto::Encryptor::CTR, "")) {
DVLOG(1) << "Could not initialize decryptor.";
return NULL;
}
DCHECK_EQ(input.decrypt_config()->iv().size(),
static_cast<size_t>(DecryptConfig::kDecryptionKeySize));
if (!encryptor.SetCounter(input.decrypt_config()->iv())) {
DVLOG(1) << "Could not set counter block.";
return NULL;
}
const char* sample = reinterpret_cast<const char*>(input.data());
size_t sample_size = static_cast<size_t>(input.data_size());
DCHECK_GT(sample_size, 0U) << "No sample data to be decrypted.";
if (sample_size == 0)
return NULL;
if (input.decrypt_config()->subsamples().empty()) {
std::string decrypted_text;
base::StringPiece encrypted_text(sample, sample_size);
if (!encryptor.Decrypt(encrypted_text, &decrypted_text)) {
DVLOG(1) << "Could not decrypt data.";
return NULL;
}
// TODO(xhwang): Find a way to avoid this data copy.
return DecoderBuffer::CopyFrom(
reinterpret_cast<const uint8_t*>(decrypted_text.data()),
decrypted_text.size());
}
const std::vector<SubsampleEntry>& subsamples =
input.decrypt_config()->subsamples();
size_t total_clear_size = 0;
size_t total_encrypted_size = 0;
for (size_t i = 0; i < subsamples.size(); i++) {
total_clear_size += subsamples[i].clear_bytes;
total_encrypted_size += subsamples[i].cypher_bytes;
// Check for overflow. This check is valid because *_size is unsigned.
DCHECK(total_clear_size >= subsamples[i].clear_bytes);
if (total_encrypted_size < subsamples[i].cypher_bytes)
return NULL;
}
size_t total_size = total_clear_size + total_encrypted_size;
if (total_size < total_clear_size || total_size != sample_size) {
DVLOG(1) << "Subsample sizes do not equal input size";
return NULL;
}
// No need to decrypt if there is no encrypted data.
if (total_encrypted_size <= 0) {
return DecoderBuffer::CopyFrom(reinterpret_cast<const uint8_t*>(sample),
sample_size);
}
// The encrypted portions of all subsamples must form a contiguous block,
// such that an encrypted subsample that ends away from a block boundary is
// immediately followed by the start of the next encrypted subsample. We
// copy all encrypted subsamples to a contiguous buffer, decrypt them, then
// copy the decrypted bytes over the encrypted bytes in the output.
// TODO(strobe): attempt to reduce number of memory copies
scoped_ptr<uint8_t[]> encrypted_bytes(new uint8_t[total_encrypted_size]);
CopySubsamples(subsamples, kSrcContainsClearBytes,
reinterpret_cast<const uint8_t*>(sample),
encrypted_bytes.get());
base::StringPiece encrypted_text(
reinterpret_cast<const char*>(encrypted_bytes.get()),
total_encrypted_size);
std::string decrypted_text;
if (!encryptor.Decrypt(encrypted_text, &decrypted_text)) {
DVLOG(1) << "Could not decrypt data.";
return NULL;
}
DCHECK_EQ(decrypted_text.size(), encrypted_text.size());
scoped_refptr<DecoderBuffer> output = DecoderBuffer::CopyFrom(
reinterpret_cast<const uint8_t*>(sample), sample_size);
CopySubsamples(subsamples, kDstContainsClearBytes,
reinterpret_cast<const uint8_t*>(decrypted_text.data()),
output->writable_data());
return output;
}
AesDecryptor::AesDecryptor(const GURL& /* security_origin */,
const SessionMessageCB& session_message_cb,
const SessionClosedCB& session_closed_cb,
const SessionKeysChangeCB& session_keys_change_cb)
: session_message_cb_(session_message_cb),
session_closed_cb_(session_closed_cb),
session_keys_change_cb_(session_keys_change_cb) {
// AesDecryptor doesn't keep any persistent data, so no need to do anything
// with |security_origin|.
DCHECK(!session_message_cb_.is_null());
DCHECK(!session_closed_cb_.is_null());
DCHECK(!session_keys_change_cb_.is_null());
}
AesDecryptor::~AesDecryptor() {
key_map_.clear();
}
void AesDecryptor::SetServerCertificate(const std::vector<uint8_t>& certificate,
scoped_ptr<SimpleCdmPromise> promise) {
promise->reject(
NOT_SUPPORTED_ERROR, 0, "SetServerCertificate() is not supported.");
}
void AesDecryptor::CreateSessionAndGenerateRequest(
SessionType session_type,
EmeInitDataType init_data_type,
const std::vector<uint8_t>& init_data,
scoped_ptr<NewSessionCdmPromise> promise) {
std::string session_id(base::UintToString(next_session_id_++));
valid_sessions_.insert(session_id);
// For now, the AesDecryptor does not care about |session_type|.
// TODO(jrummell): Validate |session_type|.
std::vector<uint8_t> message;
// TODO(jrummell): Since unprefixed will never send NULL, remove this check
// when prefixed EME is removed (http://crbug.com/249976).
if (!init_data.empty()) {
std::vector<std::vector<uint8_t>> keys;
switch (init_data_type) {
case EmeInitDataType::WEBM:
// |init_data| is simply the key needed.
keys.push_back(init_data);
break;
case EmeInitDataType::CENC:
#if defined(USE_PROPRIETARY_CODECS)
// |init_data| is a set of 0 or more concatenated 'pssh' boxes.
if (!GetKeyIdsForCommonSystemId(init_data, &keys)) {
promise->reject(NOT_SUPPORTED_ERROR, 0,
"No supported PSSH box found.");
return;
}
break;
#else
promise->reject(NOT_SUPPORTED_ERROR, 0,
"Initialization data type CENC is not supported.");
return;
#endif
case EmeInitDataType::KEYIDS: {
std::string init_data_string(init_data.begin(), init_data.end());
std::string error_message;
if (!ExtractKeyIdsFromKeyIdsInitData(init_data_string, &keys,
&error_message)) {
promise->reject(NOT_SUPPORTED_ERROR, 0, error_message);
return;
}
break;
}
default:
NOTREACHED();
promise->reject(NOT_SUPPORTED_ERROR, 0,
"init_data_type not supported.");
return;
}
CreateLicenseRequest(keys, session_type, &message);
}
promise->resolve(session_id);
// No URL needed for license requests.
GURL empty_gurl;
session_message_cb_.Run(session_id, LICENSE_REQUEST, message, empty_gurl);
}
void AesDecryptor::LoadSession(SessionType session_type,
const std::string& session_id,
scoped_ptr<NewSessionCdmPromise> promise) {
// TODO(xhwang): Change this to NOTREACHED() when blink checks for key systems
// that do not support loadSession. See http://crbug.com/342481
promise->reject(NOT_SUPPORTED_ERROR, 0, "LoadSession() is not supported.");
}
void AesDecryptor::UpdateSession(const std::string& session_id,
const std::vector<uint8_t>& response,
scoped_ptr<SimpleCdmPromise> promise) {
CHECK(!response.empty());
// TODO(jrummell): Convert back to a DCHECK once prefixed EME is removed.
if (valid_sessions_.find(session_id) == valid_sessions_.end()) {
promise->reject(INVALID_ACCESS_ERROR, 0, "Session does not exist.");
return;
}
std::string key_string(response.begin(), response.end());
KeyIdAndKeyPairs keys;
SessionType session_type = MediaKeys::TEMPORARY_SESSION;
if (!ExtractKeysFromJWKSet(key_string, &keys, &session_type)) {
promise->reject(
INVALID_ACCESS_ERROR, 0, "Response is not a valid JSON Web Key Set.");
return;
}
// Make sure that at least one key was extracted.
if (keys.empty()) {
promise->reject(
INVALID_ACCESS_ERROR, 0, "Response does not contain any keys.");
return;
}
bool key_added = false;
for (KeyIdAndKeyPairs::iterator it = keys.begin(); it != keys.end(); ++it) {
if (it->second.length() !=
static_cast<size_t>(DecryptConfig::kDecryptionKeySize)) {
DVLOG(1) << "Invalid key length: " << it->second.length();
promise->reject(INVALID_ACCESS_ERROR, 0, "Invalid key length.");
return;
}
// If this key_id doesn't currently exist in this session,
// a new key is added.
if (!HasKey(session_id, it->first))
key_added = true;
if (!AddDecryptionKey(session_id, it->first, it->second)) {
promise->reject(INVALID_ACCESS_ERROR, 0, "Unable to add key.");
return;
}
}
{
base::AutoLock auto_lock(new_key_cb_lock_);
if (!new_audio_key_cb_.is_null())
new_audio_key_cb_.Run();
if (!new_video_key_cb_.is_null())
new_video_key_cb_.Run();
}
promise->resolve();
// Create the list of all available keys for this session.
CdmKeysInfo keys_info;
{
base::AutoLock auto_lock(key_map_lock_);
for (const auto& item : key_map_) {
if (item.second->Contains(session_id)) {
keys_info.push_back(
new CdmKeyInformation(item.first, CdmKeyInformation::USABLE, 0));
}
}
}
session_keys_change_cb_.Run(session_id, key_added, std::move(keys_info));
}
void AesDecryptor::CloseSession(const std::string& session_id,
scoped_ptr<SimpleCdmPromise> promise) {
// Validate that this is a reference to an active session and then forget it.
std::set<std::string>::iterator it = valid_sessions_.find(session_id);
DCHECK(it != valid_sessions_.end());
valid_sessions_.erase(it);
// Close the session.
DeleteKeysForSession(session_id);
promise->resolve();
session_closed_cb_.Run(session_id);
}
void AesDecryptor::RemoveSession(const std::string& session_id,
scoped_ptr<SimpleCdmPromise> promise) {
// AesDecryptor doesn't keep any persistent data, so this should be
// NOT_REACHED().
// TODO(jrummell): Make sure persistent session types are rejected.
// http://crbug.com/384152.
//
// However, v0.1b calls to CancelKeyRequest() will call this, so close the
// session, if it exists.
// TODO(jrummell): Remove the close() call when prefixed EME is removed.
// http://crbug.com/249976.
if (valid_sessions_.find(session_id) != valid_sessions_.end()) {
CloseSession(session_id, std::move(promise));
return;
}
promise->reject(INVALID_ACCESS_ERROR, 0, "Session does not exist.");
}
CdmContext* AesDecryptor::GetCdmContext() {
return this;
}
Decryptor* AesDecryptor::GetDecryptor() {
return this;
}
int AesDecryptor::GetCdmId() const {
return kInvalidCdmId;
}
void AesDecryptor::RegisterNewKeyCB(StreamType stream_type,
const NewKeyCB& new_key_cb) {
base::AutoLock auto_lock(new_key_cb_lock_);
switch (stream_type) {
case kAudio:
new_audio_key_cb_ = new_key_cb;
break;
case kVideo:
new_video_key_cb_ = new_key_cb;
break;
default:
NOTREACHED();
}
}
void AesDecryptor::Decrypt(StreamType stream_type,
const scoped_refptr<DecoderBuffer>& encrypted,
const DecryptCB& decrypt_cb) {
CHECK(encrypted->decrypt_config());
scoped_refptr<DecoderBuffer> decrypted;
// An empty iv string signals that the frame is unencrypted.
if (encrypted->decrypt_config()->iv().empty()) {
decrypted = DecoderBuffer::CopyFrom(encrypted->data(),
encrypted->data_size());
} else {
const std::string& key_id = encrypted->decrypt_config()->key_id();
base::AutoLock auto_lock(key_map_lock_);
DecryptionKey* key = GetKey_Locked(key_id);
if (!key) {
DVLOG(1) << "Could not find a matching key for the given key ID.";
decrypt_cb.Run(kNoKey, NULL);
return;
}
crypto::SymmetricKey* decryption_key = key->decryption_key();
decrypted = DecryptData(*encrypted.get(), decryption_key);
if (!decrypted.get()) {
DVLOG(1) << "Decryption failed.";
decrypt_cb.Run(kError, NULL);
return;
}
}
decrypted->set_timestamp(encrypted->timestamp());
decrypted->set_duration(encrypted->duration());
decrypt_cb.Run(kSuccess, decrypted);
}
void AesDecryptor::CancelDecrypt(StreamType stream_type) {
// Decrypt() calls the DecryptCB synchronously so there's nothing to cancel.
}
void AesDecryptor::InitializeAudioDecoder(const AudioDecoderConfig& config,
const DecoderInitCB& init_cb) {
// AesDecryptor does not support audio decoding.
init_cb.Run(false);
}
void AesDecryptor::InitializeVideoDecoder(const VideoDecoderConfig& config,
const DecoderInitCB& init_cb) {
// AesDecryptor does not support video decoding.
init_cb.Run(false);
}
void AesDecryptor::DecryptAndDecodeAudio(
const scoped_refptr<DecoderBuffer>& encrypted,
const AudioDecodeCB& audio_decode_cb) {
NOTREACHED() << "AesDecryptor does not support audio decoding";
}
void AesDecryptor::DecryptAndDecodeVideo(
const scoped_refptr<DecoderBuffer>& encrypted,
const VideoDecodeCB& video_decode_cb) {
NOTREACHED() << "AesDecryptor does not support video decoding";
}
void AesDecryptor::ResetDecoder(StreamType stream_type) {
NOTREACHED() << "AesDecryptor does not support audio/video decoding";
}
void AesDecryptor::DeinitializeDecoder(StreamType stream_type) {
// AesDecryptor does not support audio/video decoding, but since this can be
// called any time after InitializeAudioDecoder/InitializeVideoDecoder,
// nothing to be done here.
}
bool AesDecryptor::AddDecryptionKey(const std::string& session_id,
const std::string& key_id,
const std::string& key_string) {
scoped_ptr<DecryptionKey> decryption_key(new DecryptionKey(key_string));
if (!decryption_key->Init()) {
DVLOG(1) << "Could not initialize decryption key.";
return false;
}
base::AutoLock auto_lock(key_map_lock_);
KeyIdToSessionKeysMap::iterator key_id_entry = key_map_.find(key_id);
if (key_id_entry != key_map_.end()) {
key_id_entry->second->Insert(session_id, std::move(decryption_key));
return true;
}
// |key_id| not found, so need to create new entry.
scoped_ptr<SessionIdDecryptionKeyMap> inner_map(
new SessionIdDecryptionKeyMap());
inner_map->Insert(session_id, std::move(decryption_key));
key_map_.add(key_id, std::move(inner_map));
return true;
}
AesDecryptor::DecryptionKey* AesDecryptor::GetKey_Locked(
const std::string& key_id) const {
key_map_lock_.AssertAcquired();
KeyIdToSessionKeysMap::const_iterator key_id_found = key_map_.find(key_id);
if (key_id_found == key_map_.end())
return NULL;
// Return the key from the "latest" session_id entry.
return key_id_found->second->LatestDecryptionKey();
}
bool AesDecryptor::HasKey(const std::string& session_id,
const std::string& key_id) {
base::AutoLock auto_lock(key_map_lock_);
KeyIdToSessionKeysMap::const_iterator key_id_found = key_map_.find(key_id);
if (key_id_found == key_map_.end())
return false;
return key_id_found->second->Contains(session_id);
}
void AesDecryptor::DeleteKeysForSession(const std::string& session_id) {
base::AutoLock auto_lock(key_map_lock_);
// Remove all keys associated with |session_id|. Since the data is
// optimized for access in GetKey_Locked(), we need to look at each entry in
// |key_map_|.
KeyIdToSessionKeysMap::iterator it = key_map_.begin();
while (it != key_map_.end()) {
it->second->Erase(session_id);
if (it->second->Empty()) {
// Need to get rid of the entry for this key_id. This will mess up the
// iterator, so we need to increment it first.
KeyIdToSessionKeysMap::iterator current = it;
++it;
key_map_.erase(current);
} else {
++it;
}
}
}
AesDecryptor::DecryptionKey::DecryptionKey(const std::string& secret)
: secret_(secret) {
}
AesDecryptor::DecryptionKey::~DecryptionKey() {}
bool AesDecryptor::DecryptionKey::Init() {
CHECK(!secret_.empty());
decryption_key_.reset(crypto::SymmetricKey::Import(
crypto::SymmetricKey::AES, secret_));
if (!decryption_key_)
return false;
return true;
}
} // namespace media
|