java中加密算法的应用一：DES

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1.DES加密算法

import java.security.Key;

import java.security.SecureRandom;

import javax.crypto.Cipher;

import javax.crypto.KeyGenerator;

/**

* 使用DES加密与解密,可对byte[],String类型进行加密与解密密文可使用String,byte[]存储.

* 方法: void getKey(String strKey)从strKey的字条生成一个Key

* String getEncString(String strMing)对strMing进行加密,返回String密文 String

* getDesString(String strMi)对strMin进行解密,返回String明文

* byte[] getEncCode(byte[] byteS)byte[]型的加密 byte[] getDesCode(byte[]

* byteD)byte[]型的解密

public class DesEncrypt {
Key key;
/**

* 根据参数生成KEY

* @param strKey

    public void getKey(String strKey) {
        try {
            KeyGenerator _generator = KeyGenerator.getInstance("DES");
            _generator.init(new SecureRandom(strKey.getBytes()));
            this.key = _generator.generateKey();
            _generator = null;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

/**

* 加密String明文输入,String密文输出

* @param strMing

* @return

    public String getEncString(String strMing) {
        byte[] byteMi = null;
        byte[] byteMing = null;
        String strMi = "";
        try {
            return byte2hex(getEncCode(strMing.getBytes()));
            // byteMing = strMing.getBytes("UTF8");
            // byteMi = this.getEncCode(byteMing);
            // strMi = new String( byteMi,"UTF8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            byteMing = null;
            byteMi = null;
        }
        return strMi;
    }

/**

* 解密以String密文输入,String明文输出

* @param strMi

* @return

    public String getDesString(String strMi) {
        byte[] byteMing = null;
        byte[] byteMi = null;
        String strMing = "";
        try {
            return new String(getDesCode(hex2byte(strMi.getBytes())));
            // byteMing = this.getDesCode(byteMi);
            // strMing = new String(byteMing,"UTF8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            byteMing = null;
            byteMi = null;
        }
        return strMing;
    }

/**

* 加密以byte[]明文输入,byte[]密文输出

* @param byteS

* @return

    private byte[] getEncCode(byte[] byteS) {
        byte[] byteFina = null;
        Cipher cipher;
        try {
            cipher = Cipher.getInstance("DES");
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byteFina = cipher.doFinal(byteS);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            cipher = null;
        }
        return byteFina;
    }

    /**

* 解密以byte[]密文输入,以byte[]明文输出

* @param byteD

* @return

private byte[] getDesCode(byte[] byteD) {
        Cipher cipher;
        byte[] byteFina = null;
        try {
            cipher = Cipher.getInstance("DES");
            cipher.init(Cipher.DECRYPT_MODE, key);
            byteFina = cipher.doFinal(byteD);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            cipher = null;
        }
        return byteFina;
    }
    /**

* 二行制转字符串

* @param b

* @return

    public static String byte2hex(byte[] b) { // 一个字节的数，
    // 转成16进制字符串
        String hs = "";
        String stmp = "";
        for (int n = 0; n < b.length; n++) {
            // 整数转成十六进制表示
            stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
            if (stmp.length() == 1)
                hs = hs + "0" + stmp;
            else
                hs = hs + stmp;
        }
        return hs.toUpperCase(); // 转成大写
    }

    public static byte[] hex2byte(byte[] b) {
        if ((b.length % 2) != 0)
            throw new IllegalArgumentException("长度不是偶数");
        byte[] b2 = new byte[b.length / 2];
        for (int n = 0; n < b.length; n += 2) {
            String item = new String(b, n, 2);
            // 两位一组，表示一个字节,把这样表示的16进制字符串，还原成一个进制字节
            b2[n / 2] = (byte) Integer.parseInt(item, 16);
        }
        return b2;
    }

    public static void main(String[] args) {
        System.out.println("----------------------start--------------------");
        DesEncrypt des = new DesEncrypt();//实例化一个对像
        des.getKey("13308472157"); //生成密钥
        String strEnc = des.getEncString("oracle.jdbc.driver.OracleDriver"); //加密字符串,返回String的密文
        System.out.println(strEnc); //打印加密后的信息
        String strDes = des.getDesString(strEnc); //把String 类型的密文解密
        System.out.println(strDes); //解密后的信息
        System.out.println("----------------------end--------------------");
    }

}