/*
* Copyright 2011-2016 the original author or authors.
*
* 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 org.springframework.security.crypto.encrypt;
import static org.springframework.security.crypto.encrypt.CipherUtils.doFinal;
import static org.springframework.security.crypto.encrypt.CipherUtils.initCipher;
import static org.springframework.security.crypto.encrypt.CipherUtils.newCipher;
import static org.springframework.security.crypto.encrypt.CipherUtils.newSecretKey;
import static org.springframework.security.crypto.util.EncodingUtils.concatenate;
import static org.springframework.security.crypto.util.EncodingUtils.subArray;
import java.security.spec.AlgorithmParameterSpec;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import org.springframework.security.crypto.codec.Hex;
import org.springframework.security.crypto.keygen.BytesKeyGenerator;
import org.springframework.security.crypto.keygen.KeyGenerators;
/**
* Encryptor that uses 256-bit AES encryption.
*
* @author Keith Donald
* @author Dave Syer
*/
final class AesBytesEncryptor implements BytesEncryptor {
private final SecretKey secretKey;
private final Cipher encryptor;
private final Cipher decryptor;
private final BytesKeyGenerator ivGenerator;
private CipherAlgorithm alg;
private static final String AES_CBC_ALGORITHM = "AES/CBC/PKCS5Padding";
private static final String AES_GCM_ALGORITHM = "AES/GCM/NoPadding";
public enum CipherAlgorithm {
CBC(AES_CBC_ALGORITHM, NULL_IV_GENERATOR), GCM(AES_GCM_ALGORITHM, KeyGenerators
.secureRandom(16));
private BytesKeyGenerator ivGenerator;
private String name;
private CipherAlgorithm(String name, BytesKeyGenerator ivGenerator) {
this.name = name;
this.ivGenerator = ivGenerator;
}
@Override
public String toString() {
return this.name;
}
public AlgorithmParameterSpec getParameterSpec(byte[] iv) {
return this == CBC ? new IvParameterSpec(iv) : new GCMParameterSpec(128, iv);
}
public Cipher createCipher() {
return newCipher(this.toString());
}
public BytesKeyGenerator defaultIvGenerator() {
return this.ivGenerator;
}
}
public AesBytesEncryptor(String password, CharSequence salt) {
this(password, salt, null);
}
public AesBytesEncryptor(String password, CharSequence salt,
BytesKeyGenerator ivGenerator) {
this(password, salt, ivGenerator, CipherAlgorithm.CBC);
}
public AesBytesEncryptor(String password, CharSequence salt,
BytesKeyGenerator ivGenerator, CipherAlgorithm alg) {
PBEKeySpec keySpec = new PBEKeySpec(password.toCharArray(), Hex.decode(salt),
1024, 256);
SecretKey secretKey = newSecretKey("PBKDF2WithHmacSHA1", keySpec);
this.secretKey = new SecretKeySpec(secretKey.getEncoded(), "AES");
this.alg = alg;
this.encryptor = alg.createCipher();
this.decryptor = alg.createCipher();
this.ivGenerator = ivGenerator != null ? ivGenerator : alg.defaultIvGenerator();
}
public byte[] encrypt(byte[] bytes) {
synchronized (this.encryptor) {
byte[] iv = this.ivGenerator.generateKey();
initCipher(this.encryptor, Cipher.ENCRYPT_MODE, this.secretKey,
this.alg.getParameterSpec(iv));
byte[] encrypted = doFinal(this.encryptor, bytes);
return this.ivGenerator != NULL_IV_GENERATOR ? concatenate(iv, encrypted)
: encrypted;
}
}
public byte[] decrypt(byte[] encryptedBytes) {
synchronized (this.decryptor) {
byte[] iv = iv(encryptedBytes);
initCipher(this.decryptor, Cipher.DECRYPT_MODE, this.secretKey,
this.alg.getParameterSpec(iv));
return doFinal(
this.decryptor,
this.ivGenerator != NULL_IV_GENERATOR ? encrypted(encryptedBytes,
iv.length) : encryptedBytes);
}
}
// internal helpers
private byte[] iv(byte[] encrypted) {
return this.ivGenerator != NULL_IV_GENERATOR ? subArray(encrypted, 0,
this.ivGenerator.getKeyLength()) : NULL_IV_GENERATOR.generateKey();
}
private byte[] encrypted(byte[] encryptedBytes, int ivLength) {
return subArray(encryptedBytes, ivLength, encryptedBytes.length);
}
private static final BytesKeyGenerator NULL_IV_GENERATOR = new BytesKeyGenerator() {
private final byte[] VALUE = new byte[16];
public int getKeyLength() {
return this.VALUE.length;
}
public byte[] generateKey() {
return this.VALUE;
}
};
}