gecko-dev/media/gmp-clearkey/0.1/ClearKeyDecryptionManager.cpp

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5.4 KiB
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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <string.h>
#include <vector>
#include "ClearKeyDecryptionManager.h"
#include "gmp-decryption.h"
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
class ClearKeyDecryptor : public RefCounted
{
public:
MOZ_IMPLICIT ClearKeyDecryptor();
void InitKey(const Key& aKey);
bool HasKey() const { return !!mKey.size(); }
GMPErr Decrypt(uint8_t* aBuffer, uint32_t aBufferSize,
const GMPEncryptedBufferMetadata* aMetadata);
const Key& DecryptionKey() const { return mKey; }
private:
~ClearKeyDecryptor();
Key mKey;
};
/* static */ ClearKeyDecryptionManager* ClearKeyDecryptionManager::sInstance = nullptr;
/* static */ ClearKeyDecryptionManager*
ClearKeyDecryptionManager::Get()
{
if (!sInstance) {
sInstance = new ClearKeyDecryptionManager();
}
return sInstance;
}
ClearKeyDecryptionManager::ClearKeyDecryptionManager()
{
CK_LOGD("ClearKeyDecryptionManager::ClearKeyDecryptionManager");
}
ClearKeyDecryptionManager::~ClearKeyDecryptionManager()
{
CK_LOGD("ClearKeyDecryptionManager::~ClearKeyDecryptionManager");
sInstance = nullptr;
for (auto it = mDecryptors.begin(); it != mDecryptors.end(); it++) {
it->second->Release();
}
mDecryptors.clear();
}
bool
ClearKeyDecryptionManager::HasSeenKeyId(const KeyId& aKeyId) const
{
CK_LOGD("ClearKeyDecryptionManager::HasSeenKeyId");
return mDecryptors.find(aKeyId) != mDecryptors.end();
}
bool
ClearKeyDecryptionManager::IsExpectingKeyForKeyId(const KeyId& aKeyId) const
{
CK_LOGD("ClearKeyDecryptionManager::IsExpectingKeyForKeyId");
const auto& decryptor = mDecryptors.find(aKeyId);
return decryptor != mDecryptors.end() && !decryptor->second->HasKey();
}
bool
ClearKeyDecryptionManager::HasKeyForKeyId(const KeyId& aKeyId) const
{
CK_LOGD("ClearKeyDecryptionManager::HasKeyForKeyId");
const auto& decryptor = mDecryptors.find(aKeyId);
return decryptor != mDecryptors.end() && decryptor->second->HasKey();
}
const Key&
ClearKeyDecryptionManager::GetDecryptionKey(const KeyId& aKeyId)
{
MOZ_ASSERT(HasKeyForKeyId(aKeyId));
return mDecryptors[aKeyId]->DecryptionKey();
}
void
ClearKeyDecryptionManager::InitKey(KeyId aKeyId, Key aKey)
{
CK_LOGD("ClearKeyDecryptionManager::InitKey");
if (IsExpectingKeyForKeyId(aKeyId)) {
mDecryptors[aKeyId]->InitKey(aKey);
}
}
void
ClearKeyDecryptionManager::ExpectKeyId(KeyId aKeyId)
{
CK_LOGD("ClearKeyDecryptionManager::ExpectKeyId");
if (!HasSeenKeyId(aKeyId)) {
mDecryptors[aKeyId] = new ClearKeyDecryptor();
}
mDecryptors[aKeyId]->AddRef();
}
void
ClearKeyDecryptionManager::ReleaseKeyId(KeyId aKeyId)
{
CK_LOGD("ClearKeyDecryptionManager::ReleaseKeyId");
ClearKeyDecryptor* decryptor = mDecryptors[aKeyId];
if (!decryptor->Release()) {
mDecryptors.erase(aKeyId);
}
}
GMPErr
ClearKeyDecryptionManager::Decrypt(uint8_t* aBuffer, uint32_t aBufferSize,
const GMPEncryptedBufferMetadata* aMetadata)
{
CK_LOGD("ClearKeyDecryptionManager::Decrypt");
KeyId keyId(aMetadata->KeyId(), aMetadata->KeyId() + aMetadata->KeyIdSize());
if (!HasKeyForKeyId(keyId)) {
return GMPNoKeyErr;
}
return mDecryptors[keyId]->Decrypt(aBuffer, aBufferSize, aMetadata);
}
ClearKeyDecryptor::ClearKeyDecryptor()
{
CK_LOGD("ClearKeyDecryptor ctor");
}
ClearKeyDecryptor::~ClearKeyDecryptor()
{
CK_LOGD("ClearKeyDecryptor dtor; key ID = %08x...", *(uint32_t*)&mKey[0]);
}
void
ClearKeyDecryptor::InitKey(const Key& aKey)
{
mKey = aKey;
}
GMPErr
ClearKeyDecryptor::Decrypt(uint8_t* aBuffer, uint32_t aBufferSize,
const GMPEncryptedBufferMetadata* aMetadata)
{
CK_LOGD("ClearKeyDecryptor::Decrypt");
// If the sample is split up into multiple encrypted subsamples, we need to
// stitch them into one continuous buffer for decryption.
std::vector<uint8_t> tmp(aBufferSize);
if (aMetadata->NumSubsamples()) {
// Take all encrypted parts of subsamples and stitch them into one
// continuous encrypted buffer.
unsigned char* data = aBuffer;
unsigned char* iter = &tmp[0];
for (size_t i = 0; i < aMetadata->NumSubsamples(); i++) {
data += aMetadata->ClearBytes()[i];
uint32_t cipherBytes = aMetadata->CipherBytes()[i];
memcpy(iter, data, cipherBytes);
data += cipherBytes;
iter += cipherBytes;
}
tmp.resize((size_t)(iter - &tmp[0]));
} else {
memcpy(&tmp[0], aBuffer, aBufferSize);
}
MOZ_ASSERT(aMetadata->IVSize() == 8 || aMetadata->IVSize() == 16);
std::vector<uint8_t> iv(aMetadata->IV(), aMetadata->IV() + aMetadata->IVSize());
iv.insert(iv.end(), CLEARKEY_KEY_LEN - aMetadata->IVSize(), 0);
ClearKeyUtils::DecryptAES(mKey, tmp, iv);
if (aMetadata->NumSubsamples()) {
// Take the decrypted buffer, split up into subsamples, and insert those
// subsamples back into their original position in the original buffer.
unsigned char* data = aBuffer;
unsigned char* iter = &tmp[0];
for (size_t i = 0; i < aMetadata->NumSubsamples(); i++) {
data += aMetadata->ClearBytes()[i];
uint32_t cipherBytes = aMetadata->CipherBytes()[i];
memcpy(data, iter, cipherBytes);
data += cipherBytes;
iter += cipherBytes;
}
} else {
memcpy(aBuffer, &tmp[0], aBufferSize);
}
return GMPNoErr;
}