AesCipherDataSource.java
/*
* Copyright (C) 2016 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.
*/
package androidx.media3.datasource;
import static androidx.media3.common.util.Assertions.checkNotNull;
import static androidx.media3.common.util.Util.castNonNull;
import android.net.Uri;
import androidx.annotation.Nullable;
import androidx.media3.common.C;
import androidx.media3.common.util.UnstableApi;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import javax.crypto.Cipher;
/** A {@link DataSource} that decrypts the data read from an upstream source. */
@UnstableApi
public final class AesCipherDataSource implements DataSource {
private final DataSource upstream;
private final byte[] secretKey;
@Nullable private AesFlushingCipher cipher;
public AesCipherDataSource(byte[] secretKey, DataSource upstream) {
this.upstream = upstream;
this.secretKey = secretKey;
}
@Override
public void addTransferListener(TransferListener transferListener) {
checkNotNull(transferListener);
upstream.addTransferListener(transferListener);
}
@Override
public long open(DataSpec dataSpec) throws IOException {
long dataLength = upstream.open(dataSpec);
cipher =
new AesFlushingCipher(
Cipher.DECRYPT_MODE,
secretKey,
dataSpec.key,
dataSpec.uriPositionOffset + dataSpec.position);
return dataLength;
}
@Override
public int read(byte[] buffer, int offset, int length) throws IOException {
if (length == 0) {
return 0;
}
int read = upstream.read(buffer, offset, length);
if (read == C.RESULT_END_OF_INPUT) {
return C.RESULT_END_OF_INPUT;
}
castNonNull(cipher).updateInPlace(buffer, offset, read);
return read;
}
@Override
@Nullable
public Uri getUri() {
return upstream.getUri();
}
@Override
public Map<String, List<String>> getResponseHeaders() {
return upstream.getResponseHeaders();
}
@Override
public void close() throws IOException {
cipher = null;
upstream.close();
}
}