Java String Descrypt decrypt(String data, String key)

Description

decrypt

License

Apache License

Declaration

public static final byte[] decrypt(String data, String key) 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * Copyright 2013 pyros2097/* w ww.j a v  a 2s .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.
 ******************************************************************************/

public class Main {
    private static final int delta = 0x9E3779B9;

    public static final byte[] decrypt(String data, String key) {
        return decrypt(data.getBytes(), key.getBytes());
    }

    public static final byte[] decrypt(byte[] data, byte[] key) {
        if (data.length == 0)
            return data;
        return toByteArray(decrypt(toIntArray(data, false), toIntArray(key, false)), true);
    }

    /**
    * Decrypt data with key.
    *
    * @param v
    * @param k
    * @return
    */
    private static final int[] decrypt(int[] v, int[] k) {
        int n = v.length - 1;

        if (n < 1) {
            return v;
        }
        if (k.length < 4) {
            int[] key = new int[4];

            System.arraycopy(k, 0, key, 0, k.length);
            k = key;
        }
        int z = v[n], y = v[0], sum, e;
        int p, q = 6 + 52 / (n + 1);

        sum = q * delta;
        while (sum != 0) {
            e = sum >>> 2 & 3;
            for (p = n; p > 0; p--) {
                z = v[p - 1];
                y = v[p] -= MX(sum, y, z, p, e, k);
            }
            z = v[n];
            y = v[0] -= MX(sum, y, z, p, e, k);
            sum = sum - delta;
        }
        return v;
    }

    /**
    * Convert int array to byte array.
    *
    * @param data
    * @param includeLength
    * @return
    */
    private static final byte[] toByteArray(int[] data, boolean includeLength) {
        int n = data.length << 2;

        if (includeLength) {
            int m = data[data.length - 1];

            if (m > n) {
                return null;
            } else {
                n = m;
            }
        }
        byte[] result = new byte[n];

        for (int i = 0; i < n; i++) {
            result[i] = (byte) ((data[i >>> 2] >>> ((i & 3) << 3)) & 0xff);
        }
        return result;
    }

    /**
    * Convert byte array to int array.
    *
    * @param data
    * @param includeLength
    * @return
    */
    private static final int[] toIntArray(byte[] data, boolean includeLength) {
        int n = (((data.length & 3) == 0) ? (data.length >>> 2) : ((data.length >>> 2) + 1));
        int[] result;

        if (includeLength) {
            result = new int[n + 1];
            result[n] = data.length;
        } else {
            result = new int[n];
        }
        n = data.length;
        for (int i = 0; i < n; i++) {
            result[i >>> 2] |= (0x000000ff & data[i]) << ((i & 3) << 3);
        }
        return result;
    }

    private static final int MX(int sum, int y, int z, int p, int e, int[] k) {
        return (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);
    }
}

Related

1. decrypt(byte[] ciphertextBytes, int r, int n)
2. decrypt(byte[] serialize)
3. decrypt(int encrypted, int salt)
4. decrypt(String arg0)
5. decrypt(String inString)
6. decrypt(String s)
7. decrypt(String s)
8. decrypt(String s, int offset)