Java XML Data Type Converter toPlaintext(String encryptedText, String password)

Description

to Plaintext

License

Apache License

Declaration

public static String toPlaintext(String encryptedText, String password) 

Method Source Code

//package com.java2s;
/**//from w  ww .j  a v a 2  s .  c o m
 * Copyright 2013 Ralph Schaer <ralphschaer@gmail.com>
 *
 * 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.
 */

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

import java.security.spec.InvalidKeySpecException;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;
import javax.xml.bind.DatatypeConverter;

public class Main {
    public static final String OBFUSCATE = "OBF";
    public static final String ENCODE = "ENC";

    public static String toPlaintext(String encryptedText, String password) {
        if (encryptedText == null) {
            return null;
        }

        if (encryptedText.startsWith(OBFUSCATE)) {
            return deobfuscate(encryptedText);
        } else if (encryptedText.startsWith(ENCODE) && password != null) {
            return decrypt(encryptedText, password);
        }

        return encryptedText;
    }

    public static String deobfuscate(String obfuscatedText) {
        String s = obfuscatedText;
        if (s.startsWith(OBFUSCATE)) {
            s = s.substring(OBFUSCATE.length());
        }

        byte[] b = new byte[s.length() / 2];
        int l = 0;
        for (int i = 0; i < s.length(); i += 4) {
            String x = s.substring(i, i + 4);
            int i0 = Integer.parseInt(x, 36);
            int i1 = i0 / 256;
            int i2 = i0 % 256;
            b[l++] = (byte) ((i1 + i2 - 254) / 2);
        }

        return new String(b, 0, l);
    }

    public static String decrypt(String encryptedText, String password) {
        try {
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
            SecretKey key = keyFactory.generateSecret(new PBEKeySpec(password.toCharArray()));
            Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");

            String enc = encryptedText.substring(ENCODE.length() + 12);
            byte[] salt = DatatypeConverter
                    .parseBase64Binary(encryptedText.substring(ENCODE.length(), ENCODE.length() + 12));

            pbeCipher.init(Cipher.DECRYPT_MODE, key, new PBEParameterSpec(salt, 20));
            return new String(pbeCipher.doFinal(DatatypeConverter.parseBase64Binary(enc)));
        } catch (InvalidKeyException | NoSuchAlgorithmException | InvalidKeySpecException | NoSuchPaddingException
                | InvalidAlgorithmParameterException | IllegalBlockSizeException | BadPaddingException e) {
            throw new RuntimeException(e);
        }

    }
}

Related

1. serializeToString(Object object)
2. serializeURLSafe(String string)
3. stringToCalendar(String value)
4. stringToData(String data)
5. toBinaryKeyId(String keyId)
6. toRoboCommand(int command)
7. toString(byte[] edid)
8. toString(final Serializable o)
9. toString(Serializable o)