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1 // Copyright 2015 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef MEDIA_BASE_ENCRYPTION_SCHEME_H_ | |
6 #define MEDIA_BASE_ENCRYPTION_SCHEME_H_ | |
7 | |
8 #include <stdint.h> | |
9 | |
10 #include "media/base/media_export.h" | |
11 | |
12 namespace media { | |
13 | |
14 // Specification of whether and how the stream is encrypted (in whole or part). | |
15 class MEDIA_EXPORT EncryptionScheme { | |
16 public: | |
17 // Algorithm and mode used for encryption. | |
18 enum CipherMode { | |
19 kCipherModeUnencrypted, | |
20 kCipherModeAesCtr, | |
21 kCipherModeDefault = kCipherModeAesCtr, | |
22 kCipherModeAesCbc, | |
23 kCipherModeMax = kCipherModeAesCbc | |
24 }; | |
25 | |
26 // V3 of the CENC standard adds pattern encryption, through two new | |
27 // protection schemes 'cens' (with AES-CTR) and 'cbcs' (with AES-CBC). | |
28 // The pattern applies only to the 'encrypted' part of the frame (as | |
29 // defined by the relevant subsample entries), and reduces further the | |
30 // actual encryption applied through a repeating pattern of (encrypt:skip) | |
31 // 16 byte blocks. For example, in a (1:9) pattern, the first block is | |
32 // encrypted, and the next nine are skipped. This pattern is applied | |
33 // repeatedly until the end of the last 16-byte block in the subsample. | |
34 // Any remaining bytes are left clear. | |
35 // If either or both of encrypt_blocks or skip_blocks is 0, pattern | |
36 // encryption is disabled. | |
37 class PatternSpec { | |
38 public: | |
39 PatternSpec(); | |
40 PatternSpec(uint32_t encrypt_blocks, uint32_t skip_blocks); | |
41 ~PatternSpec(); | |
42 | |
43 bool Matches(const PatternSpec& other) const; | |
44 | |
45 uint32_t encrypt_blocks() const { return encrypt_blocks_; } | |
46 uint32_t skip_blocks() const { return skip_blocks_; } | |
47 | |
48 bool IsInEffect() const; | |
49 | |
50 private: | |
51 uint32_t encrypt_blocks_; | |
52 uint32_t skip_blocks_; | |
53 | |
54 // Allow copy and assignment. | |
55 }; | |
56 | |
57 EncryptionScheme(); | |
ddorwin
2016/03/02 23:24:05
Clarify that this makes a "no encryption" object.
dougsteed
2016/03/03 04:45:00
Done.
| |
58 explicit EncryptionScheme(CipherMode mode); | |
59 EncryptionScheme(CipherMode mode, const PatternSpec& pattern); | |
60 ~EncryptionScheme(); | |
61 static EncryptionScheme Unencrypted(); | |
ddorwin
2016/03/02 23:24:05
This doesn't seem like a style-compliant name. It'
dougsteed
2016/03/03 04:45:00
I want this to be named as just returning a suitab
| |
62 | |
63 bool Matches(const EncryptionScheme& other) const; | |
64 | |
65 bool is_encrypted() const; | |
66 CipherMode mode() const { return mode_; } | |
67 const PatternSpec& pattern() const { return pattern_; } | |
68 | |
69 private: | |
70 CipherMode mode_; | |
71 PatternSpec pattern_; | |
72 | |
73 // Allow copy and assignment. | |
74 }; | |
75 | |
76 } // namespace media | |
77 | |
78 #endif // MEDIA_BASE_ENCRYPTION_SCHEME_H_ | |
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