/*
* Copyright 2011 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 javax.crypto.Cipher;
import javax.crypto.SecretKey;
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;
/**
* Encryptor that uses 256-bit AES encryption.
*
* @author Keith Donald
*/
final class AesBytesEncryptor implements BytesEncryptor {
private final SecretKey secretKey;
private final Cipher encryptor;
private final Cipher decryptor;
private final BytesKeyGenerator ivGenerator;
public AesBytesEncryptor(String password, CharSequence salt) {
this(password, salt, null);
}
public AesBytesEncryptor(String password, CharSequence salt, BytesKeyGenerator ivGenerator) {
PBEKeySpec keySpec = new PBEKeySpec(password.toCharArray(), Hex.decode(salt), 1024, 256);
SecretKey secretKey = newSecretKey("PBKDF2WithHmacSHA1", keySpec);
this.secretKey = new SecretKeySpec(secretKey.getEncoded(), "AES");
encryptor = newCipher(AES_ALGORITHM);
decryptor = newCipher(AES_ALGORITHM);
this.ivGenerator = ivGenerator != null ? ivGenerator : NULL_IV_GENERATOR;
}
public byte[] encrypt(byte[] bytes) {
synchronized (encryptor) {
byte[] iv = ivGenerator.generateKey();
initCipher(encryptor, Cipher.ENCRYPT_MODE, secretKey, new IvParameterSpec(iv));
byte[] encrypted = doFinal(encryptor, bytes);
return ivGenerator != NULL_IV_GENERATOR ? concatenate(iv, encrypted) : encrypted;
}
}
public byte[] decrypt(byte[] encryptedBytes) {
synchronized (decryptor) {
byte[] iv = iv(encryptedBytes);
initCipher(decryptor, Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(iv));
return doFinal(decryptor, ivGenerator != NULL_IV_GENERATOR ? encrypted(encryptedBytes, iv.length) : encryptedBytes);
}
}
// internal helpers
private byte[] iv(byte[] encrypted) {
return ivGenerator != NULL_IV_GENERATOR ? subArray(encrypted, 0, ivGenerator.getKeyLength()) : NULL_IV_GENERATOR.generateKey();
}
private byte[] encrypted(byte[] encryptedBytes, int ivLength) {
return subArray(encryptedBytes, ivLength, encryptedBytes.length);
}
private static final String AES_ALGORITHM = "AES/CBC/PKCS5Padding";
private static final BytesKeyGenerator NULL_IV_GENERATOR = new BytesKeyGenerator() {
private final byte[] VALUE = new byte[16];
public int getKeyLength() {
return VALUE.length;
}
public byte[] generateKey() {
return VALUE;
}
};
}