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/*
* Copyright (C) 2015 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 android.security;
import android.os.IBinder;
import android.security.keymaster.KeymasterArguments;
import android.security.keymaster.KeymasterDefs;
import android.security.keymaster.OperationResult;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.spec.AlgorithmParameterSpec;
import javax.crypto.MacSpi;
/**
* {@link MacSpi} which provides HMAC implementations backed by Android KeyStore.
*
* @hide
*/
public abstract class KeyStoreHmacSpi extends MacSpi implements KeyStoreCryptoOperation {
public static class HmacSHA1 extends KeyStoreHmacSpi {
public HmacSHA1() {
super(KeyStoreKeyConstraints.Digest.SHA1);
}
}
public static class HmacSHA224 extends KeyStoreHmacSpi {
public HmacSHA224() {
super(KeyStoreKeyConstraints.Digest.SHA224);
}
}
public static class HmacSHA256 extends KeyStoreHmacSpi {
public HmacSHA256() {
super(KeyStoreKeyConstraints.Digest.SHA256);
}
}
public static class HmacSHA384 extends KeyStoreHmacSpi {
public HmacSHA384() {
super(KeyStoreKeyConstraints.Digest.SHA384);
}
}
public static class HmacSHA512 extends KeyStoreHmacSpi {
public HmacSHA512() {
super(KeyStoreKeyConstraints.Digest.SHA512);
}
}
private final KeyStore mKeyStore = KeyStore.getInstance();
private final @KeyStoreKeyConstraints.DigestEnum int mDigest;
private final int mMacSizeBytes;
private String mKeyAliasInKeyStore;
// The fields below are reset by the engineReset operation.
private KeyStoreCryptoOperationChunkedStreamer mChunkedStreamer;
private IBinder mOperationToken;
private Long mOperationHandle;
protected KeyStoreHmacSpi(@KeyStoreKeyConstraints.DigestEnum int digest) {
mDigest = digest;
mMacSizeBytes = KeyStoreKeyConstraints.Digest.getOutputSizeBytes(digest);
}
@Override
protected int engineGetMacLength() {
return mMacSizeBytes;
}
@Override
protected void engineInit(Key key, AlgorithmParameterSpec params) throws InvalidKeyException,
InvalidAlgorithmParameterException {
if (key == null) {
throw new InvalidKeyException("key == null");
} else if (!(key instanceof KeyStoreSecretKey)) {
throw new InvalidKeyException(
"Only Android KeyStore secret keys supported. Key: " + key);
}
if (params != null) {
throw new InvalidAlgorithmParameterException(
"Unsupported algorithm parameters: " + params);
}
mKeyAliasInKeyStore = ((KeyStoreSecretKey) key).getAlias();
if (mKeyAliasInKeyStore == null) {
throw new InvalidKeyException("Key's KeyStore alias not known");
}
engineReset();
ensureKeystoreOperationInitialized();
}
@Override
protected void engineReset() {
IBinder operationToken = mOperationToken;
if (operationToken != null) {
mOperationToken = null;
mKeyStore.abort(operationToken);
}
mOperationHandle = null;
mChunkedStreamer = null;
}
private void ensureKeystoreOperationInitialized() {
if (mChunkedStreamer != null) {
return;
}
if (mKeyAliasInKeyStore == null) {
throw new IllegalStateException("Not initialized");
}
KeymasterArguments keymasterArgs = new KeymasterArguments();
keymasterArgs.addInt(KeymasterDefs.KM_TAG_ALGORITHM, KeyStoreKeyConstraints.Algorithm.HMAC);
keymasterArgs.addInt(KeymasterDefs.KM_TAG_DIGEST, mDigest);
OperationResult opResult = mKeyStore.begin(mKeyAliasInKeyStore,
KeymasterDefs.KM_PURPOSE_SIGN,
true,
keymasterArgs,
null,
new KeymasterArguments());
if (opResult == null) {
throw new KeyStoreConnectException();
} else if (opResult.resultCode != KeyStore.NO_ERROR) {
throw KeyStore.getCryptoOperationException(opResult.resultCode);
}
if (opResult.token == null) {
throw new CryptoOperationException("Keystore returned null operation token");
}
mOperationToken = opResult.token;
mOperationHandle = opResult.operationHandle;
mChunkedStreamer = new KeyStoreCryptoOperationChunkedStreamer(
new KeyStoreCryptoOperationChunkedStreamer.MainDataStream(
mKeyStore, mOperationToken));
}
@Override
protected void engineUpdate(byte input) {
engineUpdate(new byte[] {input}, 0, 1);
}
@Override
protected void engineUpdate(byte[] input, int offset, int len) {
ensureKeystoreOperationInitialized();
byte[] output;
try {
output = mChunkedStreamer.update(input, offset, len);
} catch (KeyStoreException e) {
throw KeyStore.getCryptoOperationException(e);
}
if ((output != null) && (output.length != 0)) {
throw new CryptoOperationException("Update operation unexpectedly produced output");
}
}
@Override
protected byte[] engineDoFinal() {
ensureKeystoreOperationInitialized();
byte[] result;
try {
result = mChunkedStreamer.doFinal(null, 0, 0);
} catch (KeyStoreException e) {
throw KeyStore.getCryptoOperationException(e);
}
engineReset();
return result;
}
@Override
public void finalize() throws Throwable {
try {
IBinder operationToken = mOperationToken;
if (operationToken != null) {
mKeyStore.abort(operationToken);
}
} finally {
super.finalize();
}
}
@Override
public Long getOperationHandle() {
return mOperationHandle;
}
}
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