经常使用加密算法:DES、3DES、RC4、AES，RSA等;
对称加密：des，3des，aes
非对称加密：rsa
不可逆加密：md5
加密模式:ECB、CBC、CFB、OFB等;
填充模式:NoPadding、PKCS1Padding、PKCS5Padding、PKCS7Padding

package com.changhong.settings.iptv.util;

import android.text.TextUtils;
import android.util.Base64;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
 * Created by libeibei on 2018/3/9 0009.
 */

public class EncryptionTool {

    /**
     * MD5加密
     * @param str
     * @return
     */
    public static final String getMD5String(String str) {
        char hexDigits[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                'A', 'B', 'C', 'D', 'E', 'F'};
        try {

            byte[] btInput = str.getBytes();
            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
            messageDigest.update(btInput);
            //获得密文
            byte[] cipherbyte = messageDigest.digest();
            int len = cipherbyte.length;
            char string[] = new char[len * 2];
            int k = 0;
            for (int i = 0; i < len; i++) {
                byte byte0 = cipherbyte[i];
                string[k++] = hexDigits[byte0 >>> 4 & 0xf];
                string[k++] = hexDigits[byte0 & 0xf];
            }
            return new String(string);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }


    // 定义加密算法，DESede即3DES
    private static final String Algorithm = "DESede";

    private static final String Key = "123456781234567812345678";

    /**
     * 3DES加密
     * @param str
     * @return
     */
    public static String get3DesString(String str){
        if(!TextUtils.isEmpty(str)){
            byte[] enBytes = encryptMode(Key, str.getBytes());
            return Base64.encodeToString(enBytes,Base64.DEFAULT);
        }else{
            return null;
        }
    }
    /**
     * 加密
     * @param key
     * @param src
     * @return
     */
    private static byte[] encryptMode(String key, byte[] src) {
        try {
            SecretKey deskey = new SecretKeySpec(build3DesKey(key), Algorithm);
            Cipher cipher = Cipher.getInstance(Algorithm);
            cipher.init(Cipher.ENCRYPT_MODE, deskey);
            return cipher.doFinal(src);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 3DES解密
     * @return
     */
    public static String getDe3DesString(String str){
        if(!TextUtils.isEmpty(str)){
            byte[] enBytes = Base64.decode(str,Base64.DEFAULT);
            byte[] deBytes = decryptMode(Key, enBytes);
            return new String(deBytes);
        }else{
            return null;
        }
    }
    /**
     * 解密
     * @param key
     * @param src
     * @return
     */
    private static byte[] decryptMode(String key, byte[] src) {
        try {
            SecretKey deskey = new SecretKeySpec(build3DesKey(key), Algorithm);
            Cipher cipher = Cipher.getInstance(Algorithm);
            cipher.init(Cipher.DECRYPT_MODE, deskey);
            return cipher.doFinal(src);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }


    /**
     * 根据字符串生成密钥24位的字节数组
     * @param keyStr
     * @return
     * @throws UnsupportedEncodingException
     */
    private static byte[] build3DesKey(String keyStr) throws UnsupportedEncodingException {
        byte[] key = new byte[24];
        byte[] temp = keyStr.getBytes("UTF-8");

        if (key.length > temp.length) {
            System.arraycopy(temp, 0, key, 0, temp.length);
        } else {
            System.arraycopy(temp, 0, key, 0, key.length);
        }
        return key;
    }

       String authenticator = null;

        try {
            authenticator = byte2hex(des3EncodeECB(password.getBytes(), authStr.getBytes()));
            sb = new StringBuffer(authenticator);
        } catch (Exception e) {
            e.printStackTrace();
        }
        Log.i(TAG, "----->>>>>-----加密后的 authenticator string = " + sb.toString());
      

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

    /**
     * 3DES加密，湖北移动项目IPTV平台账号密码加密使用
     * @param key data
     * @return
     */
    private byte[] des3EncodeECB(byte[] key, byte[] data) throws Exception {
        Key deskey = null;
        DESedeKeySpec spec = new DESedeKeySpec(key);
        SecretKeyFactory keyfactory = SecretKeyFactory.getInstance("desede");
        deskey = keyfactory.generateSecret(spec);
        Cipher cipher = Cipher.getInstance("desede" + "/ECB/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, deskey);
        byte[] bOut = cipher.doFinal(data);
        return bOut;
    }


}