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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.keystore;
import android.annotation.NonNull;
import android.os.IBinder;
import android.security.KeyStore;
import android.security.KeyStoreException;
import android.security.keymaster.KeyCharacteristics;
import android.security.keymaster.KeymasterArguments;
import android.security.keymaster.KeymasterDefs;
import libcore.util.EmptyArray;
import java.io.ByteArrayOutputStream;
import java.security.InvalidKeyException;
import java.security.SignatureSpi;
/**
* Base class for {@link SignatureSpi} providing Android KeyStore backed ECDSA signatures.
*
* @hide
*/
abstract class AndroidKeyStoreECDSASignatureSpi extends AndroidKeyStoreSignatureSpiBase {
public final static class NONE extends AndroidKeyStoreECDSASignatureSpi {
public NONE() {
super(KeymasterDefs.KM_DIGEST_NONE);
}
@Override
protected KeyStoreCryptoOperationStreamer createMainDataStreamer(KeyStore keyStore,
IBinder operationToken) {
return new TruncateToFieldSizeMessageStreamer(
super.createMainDataStreamer(keyStore, operationToken),
getGroupSizeBits());
}
/**
* Streamer which buffers all input, then truncates it to field size, and then sends it into
* KeyStore via the provided delegate streamer.
*/
private static class TruncateToFieldSizeMessageStreamer
implements KeyStoreCryptoOperationStreamer {
private final KeyStoreCryptoOperationStreamer mDelegate;
private final int mGroupSizeBits;
private final ByteArrayOutputStream mInputBuffer = new ByteArrayOutputStream();
private long mConsumedInputSizeBytes;
private TruncateToFieldSizeMessageStreamer(
KeyStoreCryptoOperationStreamer delegate,
int groupSizeBits) {
mDelegate = delegate;
mGroupSizeBits = groupSizeBits;
}
@Override
public byte[] update(byte[] input, int inputOffset, int inputLength)
throws KeyStoreException {
if (inputLength > 0) {
mInputBuffer.write(input, inputOffset, inputLength);
mConsumedInputSizeBytes += inputLength;
}
return EmptyArray.BYTE;
}
@Override
public byte[] doFinal(byte[] input, int inputOffset, int inputLength, byte[] signature,
byte[] additionalEntropy) throws KeyStoreException {
if (inputLength > 0) {
mConsumedInputSizeBytes += inputLength;
mInputBuffer.write(input, inputOffset, inputLength);
}
byte[] bufferedInput = mInputBuffer.toByteArray();
mInputBuffer.reset();
// Truncate input at field size (bytes)
return mDelegate.doFinal(bufferedInput,
0,
Math.min(bufferedInput.length, ((mGroupSizeBits + 7) / 8)),
signature, additionalEntropy);
}
@Override
public long getConsumedInputSizeBytes() {
return mConsumedInputSizeBytes;
}
@Override
public long getProducedOutputSizeBytes() {
return mDelegate.getProducedOutputSizeBytes();
}
}
}
public final static class SHA1 extends AndroidKeyStoreECDSASignatureSpi {
public SHA1() {
super(KeymasterDefs.KM_DIGEST_SHA1);
}
}
public final static class SHA224 extends AndroidKeyStoreECDSASignatureSpi {
public SHA224() {
super(KeymasterDefs.KM_DIGEST_SHA_2_224);
}
}
public final static class SHA256 extends AndroidKeyStoreECDSASignatureSpi {
public SHA256() {
super(KeymasterDefs.KM_DIGEST_SHA_2_256);
}
}
public final static class SHA384 extends AndroidKeyStoreECDSASignatureSpi {
public SHA384() {
super(KeymasterDefs.KM_DIGEST_SHA_2_384);
}
}
public final static class SHA512 extends AndroidKeyStoreECDSASignatureSpi {
public SHA512() {
super(KeymasterDefs.KM_DIGEST_SHA_2_512);
}
}
private final int mKeymasterDigest;
private int mGroupSizeBits = -1;
AndroidKeyStoreECDSASignatureSpi(int keymasterDigest) {
mKeymasterDigest = keymasterDigest;
}
@Override
protected final void initKey(AndroidKeyStoreKey key) throws InvalidKeyException {
if (!KeyProperties.KEY_ALGORITHM_EC.equalsIgnoreCase(key.getAlgorithm())) {
throw new InvalidKeyException("Unsupported key algorithm: " + key.getAlgorithm()
+ ". Only" + KeyProperties.KEY_ALGORITHM_EC + " supported");
}
KeyCharacteristics keyCharacteristics = new KeyCharacteristics();
int errorCode = getKeyStore().getKeyCharacteristics(
key.getAlias(), null, null, keyCharacteristics);
if (errorCode != KeyStore.NO_ERROR) {
throw getKeyStore().getInvalidKeyException(key.getAlias(), errorCode);
}
long keySizeBits = keyCharacteristics.getUnsignedInt(KeymasterDefs.KM_TAG_KEY_SIZE, -1);
if (keySizeBits == -1) {
throw new InvalidKeyException("Size of key not known");
} else if (keySizeBits > Integer.MAX_VALUE) {
throw new InvalidKeyException("Key too large: " + keySizeBits + " bits");
}
mGroupSizeBits = (int) keySizeBits;
super.initKey(key);
}
@Override
protected final void resetAll() {
mGroupSizeBits = -1;
super.resetAll();
}
@Override
protected final void resetWhilePreservingInitState() {
super.resetWhilePreservingInitState();
}
@Override
protected final void addAlgorithmSpecificParametersToBegin(
@NonNull KeymasterArguments keymasterArgs) {
keymasterArgs.addEnum(KeymasterDefs.KM_TAG_ALGORITHM, KeymasterDefs.KM_ALGORITHM_EC);
keymasterArgs.addEnum(KeymasterDefs.KM_TAG_DIGEST, mKeymasterDigest);
}
@Override
protected final int getAdditionalEntropyAmountForSign() {
return (mGroupSizeBits + 7) / 8;
}
protected final int getGroupSizeBits() {
if (mGroupSizeBits == -1) {
throw new IllegalStateException("Not initialized");
}
return mGroupSizeBits;
}
}
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