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/*
* Copyright (C) 2019 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 com.android.internal.net.ipsec.ike.crypto;
import com.android.internal.net.crypto.KeyGenerationUtils.ByteSigner;
import java.nio.ByteBuffer;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.Provider;
import javax.crypto.Cipher;
import javax.crypto.Mac;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;
/**
* IkeMac is an abstract class that represents common information for all negotiated algorithms that
* generates Message Authentication Code (MAC), e.g. PRF and integrity algorithm.
*/
abstract class IkeMac extends IkeCrypto implements ByteSigner {
// STOPSHIP: b/130190639 Catch unchecked exceptions, notify users and close the IKE session.
private final boolean mIsEncryptAlgo;
private final Mac mMac;
private final Cipher mCipher;
protected IkeMac(
int algorithmId,
int keyLength,
String algorithmName,
boolean isEncryptAlgo,
Provider provider) {
super(algorithmId, keyLength, algorithmName);
mIsEncryptAlgo = isEncryptAlgo;
try {
if (mIsEncryptAlgo) {
mMac = null;
mCipher = Cipher.getInstance(getAlgorithmName(), provider);
} else {
mMac = Mac.getInstance(getAlgorithmName(), provider);
mCipher = null;
}
} catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
throw new IllegalArgumentException("Failed to construct " + getTypeString(), e);
}
}
/**
* Signs the bytes to generate a Message Authentication Code (MAC).
*
* <p>Caller is responsible for providing valid key according to their use cases (e.g. PSK,
* SK_p, SK_d ...).
*
* @param keyBytes the key to sign data.
* @param dataToSign the data to be signed.
* @return the calculated MAC.
*/
@Override
public byte[] signBytes(byte[] keyBytes, byte[] dataToSign) {
try {
SecretKeySpec secretKey = new SecretKeySpec(keyBytes, getAlgorithmName());
if (mIsEncryptAlgo) {
throw new UnsupportedOperationException(
"Do not support " + getTypeString() + " using encryption algorithm.");
} else {
ByteBuffer inputBuffer = ByteBuffer.wrap(dataToSign);
mMac.init(secretKey);
mMac.update(inputBuffer);
return mMac.doFinal();
}
} catch (InvalidKeyException | IllegalStateException e) {
throw new IllegalArgumentException("Failed to generate MAC: ", e);
}
}
}
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