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/*
* 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.commons.vfs2.util;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
/**
* Allows passwords to be encrypted and decrypted.
*
* Warning: This uses AES128 with a fixed encryption key. This is only an obfuscation no cryptographic secure
* protection.
*
*
* @since 2.0
*/
public class DefaultCryptor implements Cryptor {
private static final char[] HEX_CHARS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E',
'F' };
private static final byte[] KEY_BYTES = { 0x41, 0x70, 0x61, 0x63, 0x68, 0x65, 0x43, 0x6F, 0x6D, 0x6D, 0x6F, 0x6E,
0x73, 0x56, 0x46, 0x53 };
private static final int INDEX_NOT_FOUND = -1;
private static final int BITS_IN_HALF_BYTE = 4;
private static final char MASK = 0x0f;
/**
* Encrypt the plain text password.
*
* Warning: This uses AES128 with a fixed encryption key. This is only an obfuscation no cryptographic secure
* protection.
*
* @param plainKey The password.
* @return The encrypted password String.
* @throws Exception If an error occurs.
*/
@Override
public String encrypt(final String plainKey) throws Exception {
final byte[] input = plainKey.getBytes();
final SecretKeySpec key = new SecretKeySpec(KEY_BYTES, "AES");
final Cipher cipher = Cipher.getInstance("AES");
// encryption pass
cipher.init(Cipher.ENCRYPT_MODE, key);
final byte[] cipherText = new byte[cipher.getOutputSize(input.length)];
int ctLength = cipher.update(input, 0, input.length, cipherText, 0);
ctLength += cipher.doFinal(cipherText, ctLength);
return encode(cipherText);
}
/**
* Decrypts the password.
*
* @param encryptedKey the encrypted password.
* @return The plain text password.
* @throws Exception If an error occurs.
*/
@Override
public String decrypt(final String encryptedKey) throws Exception {
final SecretKeySpec key = new SecretKeySpec(KEY_BYTES, "AES");
final Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, key);
final byte[] decoded = decode(encryptedKey);
final byte[] plainText = new byte[cipher.getOutputSize(decoded.length)];
int ptLength = cipher.update(decoded, 0, decoded.length, plainText, 0);
ptLength += cipher.doFinal(plainText, ptLength);
return new String(plainText).substring(0, ptLength);
}
/** Hex-encode bytes. */
private String encode(final byte[] bytes) {
final StringBuilder builder = new StringBuilder();
for (final byte b : bytes) {
builder.append(HEX_CHARS[(b >> BITS_IN_HALF_BYTE) & MASK]);
builder.append(HEX_CHARS[b & MASK]);
}
return builder.toString();
}
/** Decodes Hex-Bytes. */
private byte[] decode(final String str) {
final char[] chars = str.toCharArray();
final int length = chars.length / 2;
final byte[] decoded = new byte[length];
if (length * 2 != chars.length)
{
throw new IllegalArgumentException("The given string must have even number of hex chars.");
}
int index = 0;
for (int i = 0; i < length; i++) {
final int id1 = indexOf(HEX_CHARS, chars[index++]);
if (id1 == INDEX_NOT_FOUND) {
throw new IllegalArgumentException(
"Character " + chars[index-1] + " at position " + (index-1) + " is not a valid hexidecimal character");
}
final int id2 = indexOf(HEX_CHARS, chars[index++]);
if (id2 == INDEX_NOT_FOUND) {
throw new IllegalArgumentException(
"Character " + chars[index-1] + " at position " + (index-1) + " is not a valid hexidecimal character");
}
decoded[i] = (byte) ((id1 << BITS_IN_HALF_BYTE) | id2);
}
return decoded;
}
private int indexOf(final char[] array, final char valueToFind) {
if (array == null) {
return INDEX_NOT_FOUND;
}
for (int i = 0; i < array.length; i++) {
if (valueToFind == array[i]) {
return i;
}
}
return INDEX_NOT_FOUND;
}
}