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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//#define LOG_NDEBUG 0
#define LOG_TAG "ClearKeyCryptoPlugin"
#include <utils/Log.h>
#include <media/stagefright/MediaErrors.h>
#include <utils/Errors.h>
#include "CryptoPlugin.h"
namespace clearkeydrm {
using android::Vector;
using android::AString;
using android::status_t;
// Returns negative values for error code and positive values for the size of
// decrypted data. In theory, the output size can be larger than the input
// size, but in practice this will never happen for AES-CTR.
ssize_t CryptoPlugin::decrypt(bool secure, const KeyId keyId, const Iv iv,
Mode mode, const void* srcPtr,
const SubSample* subSamples, size_t numSubSamples,
void* dstPtr, AString* errorDetailMsg) {
if (secure) {
errorDetailMsg->setTo("Secure decryption is not supported with "
"ClearKey.");
return android::ERROR_DRM_CANNOT_HANDLE;
}
if (mode == kMode_Unencrypted) {
size_t offset = 0;
for (size_t i = 0; i < numSubSamples; ++i) {
const SubSample& subSample = subSamples[i];
if (subSample.mNumBytesOfEncryptedData != 0) {
errorDetailMsg->setTo(
"Encrypted subsamples found in allegedly unencrypted "
"data.");
return android::ERROR_DRM_DECRYPT;
}
if (subSample.mNumBytesOfClearData != 0) {
memcpy(reinterpret_cast<uint8_t*>(dstPtr) + offset,
reinterpret_cast<const uint8_t*>(srcPtr) + offset,
subSample.mNumBytesOfClearData);
offset += subSample.mNumBytesOfClearData;
}
}
return static_cast<ssize_t>(offset);
} else if (mode == kMode_AES_CTR) {
size_t bytesDecrypted;
status_t res = mSession->decrypt(keyId, iv, srcPtr, dstPtr, subSamples,
numSubSamples, &bytesDecrypted);
if (res == android::OK) {
return static_cast<ssize_t>(bytesDecrypted);
} else {
errorDetailMsg->setTo("Decryption Error");
return static_cast<ssize_t>(res);
}
} else {
errorDetailMsg->setTo(
"Selected encryption mode is not supported by the ClearKey DRM "
"Plugin.");
return android::ERROR_DRM_CANNOT_HANDLE;
}
}
} // namespace clearkeydrm
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