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1 // Copyright (c) 2012 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_CRYPTO_HMAC_AES_DECRYPTOR_H_ | |
6 #define MEDIA_CRYPTO_HMAC_AES_DECRYPTOR_H_ | |
7 | |
8 #include <string> | |
9 | |
10 #include "base/basictypes.h" | |
11 #include "base/hash_tables.h" | |
12 #include "base/memory/scoped_ptr.h" | |
13 #include "media/base/media_export.h" | |
14 #include "media/crypto/decryptor.h" | |
15 | |
16 namespace crypto { | |
17 class SymmetricKey; | |
18 } | |
19 | |
20 namespace media { | |
21 | |
22 class DecoderBuffer; | |
23 | |
24 // Checks the integrity of the encrypted data and decrypts the AES encrypted | |
25 // buffer into an unencrypted buffer. | |
26 class MEDIA_EXPORT HmacAesDecryptor : public Decryptor { | |
xhwang
2012/06/14 19:42:27
With the new HmacAesDecryptor, we don't need to ke
ddorwin
2012/06/14 21:41:24
I think we should just keep the name AesDecryptor.
fgalligan1
2012/07/03 22:00:15
The media stack cannot create the same CDM for CEN
| |
27 public: | |
28 // The size is from the WebM encrypted specification. Current WebM | |
29 // encrypted request for comments specification is here | |
30 // http://wiki.webmproject.org/encryption/webm-encryption-rfc. | |
31 static const int kSha1DigestSize = 20; | |
32 static const char kHmacSeed[]; | |
33 static const char kEncryptionSeed[]; | |
34 | |
35 HmacAesDecryptor(); | |
36 virtual ~HmacAesDecryptor(); | |
37 | |
38 // Decryptor implementation. | |
39 // Add a |key_id| and |key| pair to the key system. The key is not limited to | |
40 // a decryption key. It can be any data that the key system accepts, such as | |
41 // a license. If multiple calls of this function set different keys for the | |
42 // same |key_id|, the older key will be replaced by the newer key. | |
43 virtual void AddKey(const uint8* key_id, int key_id_size, | |
44 const uint8* key, int key_size) OVERRIDE; | |
45 | |
46 // Check and Decrypt |input| buffer. The |input| should not be NULL. | |
47 // Return a DecoderBuffer with the decrypted data if the check and | |
48 // decryption succeeded. Return NULL if check or decryption failed. | |
49 // TODO(fgalligan): Do we need to differentiate between a check failure | |
50 // and a decryption failure? | |
51 virtual scoped_refptr<DecoderBuffer> Decrypt( | |
52 const scoped_refptr<DecoderBuffer>& input) OVERRIDE; | |
53 | |
54 private: | |
55 // Helper class that manages the HMAC and encryption keys. | |
56 class HmacEncryptionKeys { | |
57 public: | |
58 explicit HmacEncryptionKeys(const std::string& secret); | |
59 ~HmacEncryptionKeys(); | |
60 | |
61 // Creates the HMAC and encryption key. | |
62 bool Init(); | |
63 | |
64 std::string hmac_key() { return hmac_key_; } | |
65 crypto::SymmetricKey* encryption_key() { return encryption_key_.get(); } | |
66 | |
67 private: | |
68 // The base secret that is used to derive the HMAC and encryption keys. | |
69 const std::string secret_; | |
70 | |
71 // The key used to perform the intergrity check. | |
72 std::string hmac_key_; | |
73 | |
74 // The key used to decrypt the data. | |
75 scoped_ptr<crypto::SymmetricKey> encryption_key_; | |
76 }; | |
77 | |
78 // KeysMap owns the HmacEncryptionKeys* and must delete them when they are | |
79 // not needed any more. | |
80 typedef base::hash_map<std::string, HmacEncryptionKeys*> KeysMap; | |
81 KeysMap keys_map_; | |
82 | |
83 DISALLOW_COPY_AND_ASSIGN(HmacAesDecryptor); | |
84 }; | |
85 | |
86 } // namespace media | |
87 | |
88 #endif // MEDIA_CRYPTO_HMAC_AES_DECRYPTOR_H_ | |
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