使用DES算法进行加密和解密

java 代码

package com.gemt.dataswap.security;

import java.security.Security;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import com.gemt.dataswap.util.Constants;

public class DES {
    public static int _DES = 1;
    public static int _DESede = 2;
    public static int _Blowfish = 3;
    private Cipher p_Cipher;
    private SecretKey p_Key;
    private String p_Algorithm;

    private void selectAlgorithm(int al) {
        switch (al) {
            default:
            case 1:
                this.p_Algorithm = "DES";
                break;
            case 2:
                this.p_Algorithm = "DESede";
                break;
            case 3:
                this.p_Algorithm = "Blowfish";
                break;
        }
    }

    public DES(int algorithm) throws Exception {
        this.selectAlgorithm(algorithm);
        Security.addProvider(new com.sun.crypto.provider.SunJCE());
        this.p_Cipher = Cipher.getInstance(this.p_Algorithm);
    }

    public byte[] getKey() {
        return this.checkKey().getEncoded();
    }

    private SecretKey checkKey() {
        try {
            if (this.p_Key == null) {
                KeyGenerator keygen = KeyGenerator.getInstance(this.p_Algorithm);
                /*
                SecureRandom sr = new SecureRandom(key.getBytes());
                keygen.init(168, sr);*/
                this.p_Key = keygen.generateKey();
            }
        }
        catch (Exception nsae) {}
        return this.p_Key;
    }

    public void setKey(byte[] enckey) {
        this.p_Key = new SecretKeySpec(enckey, this.p_Algorithm);
    }

    public byte[] encode(byte[] data) throws Exception {
        this.p_Cipher.init(Cipher.ENCRYPT_MODE, this.checkKey());
        return this.p_Cipher.doFinal(data);
    }

    public byte[] decode(byte[] encdata, byte[] enckey) throws Exception {
        this.setKey(enckey);
        this.p_Cipher.init(Cipher.DECRYPT_MODE, this.p_Key);
        return this.p_Cipher.doFinal(encdata);
    }

    public String byte2hex(byte[] b) {
        String hs = "";
        String stmp = "";
        for (int i = 0; i < b.length; i++) {
            stmp = Integer.toHexString(b[i] & 0xFF);
            if (stmp.length() == 1) {
                hs += "0" + stmp;
            }
            else {
                hs += stmp;
            }
        }
        return hs.toUpperCase();
    }

    public byte[] hex2byte(String hex) throws IllegalArgumentException {
        if (hex.length() % 2 != 0) {
            throw new IllegalArgumentException();
        }
        char[] arr = hex.toCharArray();
        byte[] b = new byte[hex.length() / 2];
        for (int i = 0, j = 0, l = hex.length(); i < l; i++, j++) {
            String swap = "" + arr[i++] + arr[i];
            int byteint = Integer.parseInt(swap, 16) & 0xFF;
            b[j] = new Integer(byteint).byteValue();
        }
        return b;
    }

    /**
     * this is DES algorithm, the string will be encode become hex
     * @param info
     * @return
     * @throws Exception
     */
    public String encode(String info, byte[] key) {
        setKey(key);
        try{
            return byte2hex(encode(info.getBytes()));
        }
        catch (Exception e)
        {
            return info;
        }
    }

    /**
     * this is DES algorithm, the string will be decode from hex text
     * @param info
     * @return
     * @throws Exception
     */
    public String decode(String info, byte[] key) {
        try {
            return new String(decode(hex2byte(info), key));
        }
        catch (Exception e)
        {
            return info;
        }
    }

    public String decode(String info, String hexkey) throws IllegalArgumentException, Exception {
        return new String(decode(hex2byte(info), hex2byte(hexkey)));
    }

    public static void main(String[] args) throws Exception {
        /*
        String info = "要加密的字串";
        System.out.println("region string:" + info);
        byte[] key; //密钥文件(byte)
        DES des = new DES(DES._DESede); // 声明DES
        //key = des.getKey(); //获取随机生成的密钥
        key = "thisisgeomatthisisgeomat".getBytes();
        des.setKey(key);
        System.out.println("key's length is " + key.length);
        System.out.println("encrypted key(byte):" + new String(key));
        String hexkey = des.byte2hex(key); //生成十六进制密钥
        System.out.println("encrypted key(hex):" + hexkey);
        byte[] enc = des.encode(info.getBytes()); //生成加密文件(byte)
        System.out.println("encrypted string(byte):" + new String(enc));
        String hexenc = des.byte2hex(enc); //生成十六进制加密文件
        System.out.println("encrypted string(hex):" + hexenc);
        byte[] dec = des.decode(enc, des.hex2byte(hexkey)); //解密文件,其中转换十六进制密钥为byte
        System.out.println("decrypted string:" + new String(dec)); //生成解密文件字符串, 与info相同
        */
        DES des = new DES(DES._DESede);
        String info = "大家好，this is a encode & decode test 9875603421???";
        String passinfo = des.encode(info, Constants.PASSWORD_KEY);
        System.out.println("passinfo is :: " + passinfo);

        String oldStr = des.decode(passinfo, Constants.PASSWORD_KEY);
        System.out.println("old string is :: " + oldStr);
    }
}