org.apache.sshd.common.config.keys.loader.AESPrivateKeyObfuscator Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.sshd.common.config.keys.loader;
import java.io.IOException;
import java.security.GeneralSecurityException;
import java.security.Key;
import java.security.spec.InvalidKeySpecException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import org.apache.sshd.common.util.security.SecurityUtils;
/**
* @author Apache MINA SSHD Project
*/
public class AESPrivateKeyObfuscator extends AbstractPrivateKeyObfuscator {
public static final String CIPHER_NAME = "AES";
public static final AESPrivateKeyObfuscator INSTANCE = new AESPrivateKeyObfuscator();
public AESPrivateKeyObfuscator() {
super(CIPHER_NAME);
}
@Override
public List getSupportedKeySizes() {
return getAvailableKeyLengths();
}
@Override
public byte[] applyPrivateKeyCipher(
byte[] bytes, PrivateKeyEncryptionContext encContext, boolean encryptIt)
throws GeneralSecurityException, IOException {
int keyLength = resolveKeyLength(encContext);
byte[] keyValue = deriveEncryptionKey(encContext, keyLength / Byte.SIZE);
return applyPrivateKeyCipher(bytes, encContext, keyLength, keyValue, encryptIt);
}
@Override
protected int resolveKeyLength(PrivateKeyEncryptionContext encContext) throws GeneralSecurityException {
String cipherType = encContext.getCipherType();
try {
int keyLength = Integer.parseInt(cipherType);
List sizes = getSupportedKeySizes();
for (Integer s : sizes) {
if (s.intValue() == keyLength) {
return keyLength;
}
}
throw new InvalidKeySpecException("Unknown " + getCipherName() + " key length: " + cipherType + " - supported: " + sizes);
} catch (NumberFormatException e) {
throw new InvalidKeySpecException("Bad " + getCipherName() + " key length (" + cipherType + "): " + e.getMessage(), e);
}
}
/**
* @return A {@link List} of {@link Integer}s holding the available key
* lengths values (in bits) for the JVM. Note: AES 256 requires
* special JCE policy extension installation (e.g., for Java 7 see
* this link)
*/
@SuppressWarnings("synthetic-access")
public static List getAvailableKeyLengths() {
return LazyKeyLengthsHolder.KEY_LENGTHS;
}
private static final class LazyKeyLengthsHolder {
private static final List KEY_LENGTHS =
Collections.unmodifiableList(detectSupportedKeySizes());
private LazyKeyLengthsHolder() {
throw new UnsupportedOperationException("No instance allowed");
}
// AES 256 requires special JCE policy extension installation
private static List detectSupportedKeySizes() {
List sizes = new ArrayList<>();
for (int keyLength = 128; keyLength < Short.MAX_VALUE /* just so it doesn't go forever */; keyLength += 64) {
try {
byte[] keyAsBytes = new byte[keyLength / Byte.SIZE];
Key key = new SecretKeySpec(keyAsBytes, CIPHER_NAME);
Cipher c = SecurityUtils.getCipher(CIPHER_NAME);
c.init(Cipher.DECRYPT_MODE, key);
sizes.add(Integer.valueOf(keyLength));
} catch (GeneralSecurityException e) {
return sizes;
}
}
throw new IllegalStateException("No limit encountered: " + sizes);
}
}
}