decode data by key using DES - Android java.security

Android examples for java.security:DES

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Description

decode data by key using DES

Demo Code


//package com.java2s;

import java.security.Key;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

public class Main {
    public static final String ALGORITHM_DES = "DES/CBC/PKCS5Padding";

    public static String decode(String key, String data) {
        if (data == null)
            return null;
        try {//w  ww . j a v  a2s . co  m
            DESKeySpec dks = new DESKeySpec(key.getBytes());
            SecretKeyFactory keyFactory = SecretKeyFactory
                    .getInstance("DES");

            Key secretKey = keyFactory.generateSecret(dks);
            Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
            IvParameterSpec iv = new IvParameterSpec("12345678".getBytes());
            AlgorithmParameterSpec paramSpec = iv;
            cipher.init(Cipher.DECRYPT_MODE, secretKey, paramSpec);
            return new String(cipher.doFinal(hex2byte(data.getBytes())));
        } catch (Exception e) {
            e.printStackTrace();
            return data;
        }
    }

    private static byte[] hex2byte(byte[] b) {
        if ((b.length % 2) != 0)
            throw new IllegalArgumentException();
        byte[] b2 = new byte[b.length / 2];
        for (int n = 0; n < b.length; n += 2) {
            String item = new String(b, n, 2);
            b2[n / 2] = (byte) Integer.parseInt(item, 16);
        }
        return b2;
    }
}

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