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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <media/stagefright/MediaErrors.h>
     18 #include <utils/Errors.h>
     19 #include <utils/Vector.h>
     20 
     21 #ifndef CRYPTO_API_H_
     22 
     23 #define CRYPTO_API_H_
     24 
     25 namespace android {
     26 
     27 struct AString;
     28 struct CryptoPlugin;
     29 
     30 struct CryptoFactory {
     31     CryptoFactory() {}
     32     virtual ~CryptoFactory() {}
     33 
     34     virtual bool isCryptoSchemeSupported(const uint8_t uuid[16]) const = 0;
     35 
     36     virtual status_t createPlugin(
     37             const uint8_t uuid[16], const void *data, size_t size,
     38             CryptoPlugin **plugin) = 0;
     39 
     40 private:
     41     CryptoFactory(const CryptoFactory &);
     42     CryptoFactory &operator=(const CryptoFactory &);
     43 };
     44 
     45 struct CryptoPlugin {
     46     enum Mode {
     47         kMode_Unencrypted = 0,
     48         kMode_AES_CTR     = 1,
     49         kMode_AES_WV      = 2,
     50         kMode_AES_CBC     = 3,
     51     };
     52 
     53     struct SubSample {
     54         uint32_t mNumBytesOfClearData;
     55         uint32_t mNumBytesOfEncryptedData;
     56     };
     57 
     58     struct Pattern {
     59         // Number of blocks to be encrypted in the pattern. If zero, pattern
     60         // encryption is inoperative.
     61         uint32_t mEncryptBlocks;
     62 
     63         // Number of blocks to be skipped (left clear) in the pattern. If zero,
     64         // pattern encryption is inoperative.
     65         uint32_t mSkipBlocks;
     66     };
     67 
     68     CryptoPlugin() {}
     69     virtual ~CryptoPlugin() {}
     70 
     71     // If this method returns false, a non-secure decoder will be used to
     72     // decode the data after decryption. The decrypt API below will have
     73     // to support insecure decryption of the data (secure = false) for
     74     // media data of the given mime type.
     75     virtual bool requiresSecureDecoderComponent(const char *mime) const = 0;
     76 
     77     // To implement resolution constraints, the crypto plugin needs to know
     78     // the resolution of the video being decrypted.  The media player should
     79     // call this method when the resolution is determined and any time it
     80     // is subsequently changed.
     81 
     82     virtual void notifyResolution(uint32_t /* width */, uint32_t /* height */) {}
     83 
     84     // A MediaDrm session may be associated with a MediaCrypto session.  The
     85     // associated MediaDrm session is used to load decryption keys
     86     // into the crypto/drm plugin.  The keys are then referenced by key-id
     87     // in the 'key' parameter to the decrypt() method.
     88     // Should return NO_ERROR on success, ERROR_DRM_SESSION_NOT_OPENED if
     89     // the session is not opened and a code from MediaErrors.h otherwise.
     90     virtual status_t setMediaDrmSession(const Vector<uint8_t> & /*sessionId */) {
     91         return ERROR_UNSUPPORTED;
     92     }
     93 
     94     // If the error returned falls into the range
     95     // ERROR_DRM_VENDOR_MIN..ERROR_DRM_VENDOR_MAX, errorDetailMsg should be
     96     // filled in with an appropriate string.
     97     // At the java level these special errors will then trigger a
     98     // MediaCodec.CryptoException that gives clients access to both
     99     // the error code and the errorDetailMsg.
    100     // Returns a non-negative result to indicate the number of bytes written
    101     // to the dstPtr, or a negative result to indicate an error.
    102     virtual ssize_t decrypt(
    103             bool secure,
    104             const uint8_t key[16],
    105             const uint8_t iv[16],
    106             Mode mode,
    107             const Pattern &pattern,
    108             const void *srcPtr,
    109             const SubSample *subSamples, size_t numSubSamples,
    110             void *dstPtr,
    111             AString *errorDetailMsg) = 0;
    112 
    113 private:
    114     CryptoPlugin(const CryptoPlugin &);
    115     CryptoPlugin &operator=(const CryptoPlugin &);
    116 };
    117 
    118 }  // namespace android
    119 
    120 extern "C" {
    121     extern android::CryptoFactory *createCryptoFactory();
    122 }
    123 
    124 #endif  // CRYPTO_API_H_
    125