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/*
* 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 org.mozilla.thirdparty.com.google.android.exoplayer2.source.hls;
import android.net.Uri;
import androidx.annotation.Nullable;
import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.DataSource;
import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.DataSourceInputStream;
import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.DataSpec;
import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.TransferListener;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions;
import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;
import java.util.List;
import java.util.Map;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
/**
* A {@link DataSource} that decrypts data read from an upstream source, encrypted with AES-128 with
* a 128-bit key and PKCS7 padding.
*
* <p>Note that this {@link DataSource} does not support being opened from arbitrary offsets. It is
* designed specifically for reading whole files as defined in an HLS media playlist. For this
* reason the implementation is private to the HLS package.
*/
/* package */ class Aes128DataSource implements DataSource {
private final DataSource upstream;
private final byte[] encryptionKey;
private final byte[] encryptionIv;
@Nullable private CipherInputStream cipherInputStream;
/**
* @param upstream The upstream {@link DataSource}.
* @param encryptionKey The encryption key.
* @param encryptionIv The encryption initialization vector.
*/
public Aes128DataSource(DataSource upstream, byte[] encryptionKey, byte[] encryptionIv) {
this.upstream = upstream;
this.encryptionKey = encryptionKey;
this.encryptionIv = encryptionIv;
}
@Override
public final void addTransferListener(TransferListener transferListener) {
upstream.addTransferListener(transferListener);
}
@Override
public final long open(DataSpec dataSpec) throws IOException {
Cipher cipher;
try {
cipher = getCipherInstance();
} catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
throw new RuntimeException(e);
}
Key cipherKey = new SecretKeySpec(encryptionKey, "AES");
AlgorithmParameterSpec cipherIV = new IvParameterSpec(encryptionIv);
try {
cipher.init(Cipher.DECRYPT_MODE, cipherKey, cipherIV);
} catch (InvalidKeyException | InvalidAlgorithmParameterException e) {
throw new RuntimeException(e);
}
DataSourceInputStream inputStream = new DataSourceInputStream(upstream, dataSpec);
cipherInputStream = new CipherInputStream(inputStream, cipher);
inputStream.open();
return C.LENGTH_UNSET;
}
@Override
public final int read(byte[] buffer, int offset, int readLength) throws IOException {
Assertions.checkNotNull(cipherInputStream);
int bytesRead = cipherInputStream.read(buffer, offset, readLength);
if (bytesRead < 0) {
return C.RESULT_END_OF_INPUT;
}
return bytesRead;
}
@Override
@Nullable
public final Uri getUri() {
return upstream.getUri();
}
@Override
public final Map<String, List<String>> getResponseHeaders() {
return upstream.getResponseHeaders();
}
@Override
public void close() throws IOException {
if (cipherInputStream != null) {
cipherInputStream = null;
upstream.close();
}
}
protected Cipher getCipherInstance() throws NoSuchPaddingException, NoSuchAlgorithmException {
return Cipher.getInstance("AES/CBC/PKCS7Padding");
}
}
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