/*
* Copyright (C)2009 - SSHJ Contributors
*
* 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 net.schmizz.sshj.transport.cipher;
import net.schmizz.sshj.common.SSHRuntimeException;
import net.schmizz.sshj.common.SecurityUtils;
import javax.crypto.ShortBufferException;
import javax.crypto.spec.SecretKeySpec;
import java.security.GeneralSecurityException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
/** Base class for all Cipher implementations delegating to the JCE provider. */
public abstract class BaseCipher
implements Cipher {
private static byte[] resize(byte[] data, int size) {
if (data.length > size) {
final byte[] tmp = new byte[size];
System.arraycopy(data, 0, tmp, 0, size);
data = tmp;
}
return data;
}
private final int ivsize;
private final int bsize;
private final String algorithm;
private final String transformation;
private javax.crypto.Cipher cipher;
public BaseCipher(int ivsize, int bsize, String algorithm, String transformation) {
this.ivsize = ivsize;
this.bsize = bsize;
this.algorithm = algorithm;
this.transformation = transformation;
}
@Override
public int getBlockSize() {
return bsize;
}
@Override
public int getIVSize() {
return ivsize;
}
@Override
public void init(Mode mode, byte[] key, byte[] iv) {
key = BaseCipher.resize(key, bsize);
iv = BaseCipher.resize(iv, ivsize);
try {
cipher = SecurityUtils.getCipher(transformation);
initCipher(cipher, mode, key, iv);
} catch (GeneralSecurityException e) {
cipher = null;
throw new SSHRuntimeException(e);
}
}
protected abstract void initCipher(javax.crypto.Cipher cipher, Mode mode, byte[] key, byte[] iv) throws InvalidKeyException, InvalidAlgorithmParameterException;
protected SecretKeySpec getKeySpec(byte[] key) {
return new SecretKeySpec(key, algorithm);
}
protected int getMode(Mode mode) {
return mode == Mode.Encrypt ? javax.crypto.Cipher.ENCRYPT_MODE : javax.crypto.Cipher.DECRYPT_MODE;
}
@Override
public void update(byte[] input, int inputOffset, int inputLen) {
try {
cipher.update(input, inputOffset, inputLen, input, inputOffset);
} catch (ShortBufferException e) {
throw new SSHRuntimeException(e);
}
}
}