客户端使用公钥进行加密，服务端使用密钥进行解密

使用rsa非对称加密吧，客户端使用公钥进行加密，服务端使用密钥进行解密。

我觉得你最好使用JAVA 进行DES加密和解密 

（JAVA 的核心API中已经实现过DES加密，JAVASCRIPT实现DES加密我没做过）

下面是JAVA版的DES加密 希望对你有帮助：

import  java.security.Key;
import  java.security.SecureRandom;
import  javax.crypto.Cipher;
import  javax.crypto.KeyGenerator;
import  sun.misc.BASE64Decoder;
import  sun.misc.BASE64Encoder;

public  class  Des {
    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             String明文
   * @return                    String密文
   */
  public  String getEncString(String strMing) {
    byte [] byteMi =  null ;
    byte [] byteMing =  null ;
    String strMi =  "" ;
    BASE64Encoder base64en =  new  BASE64Encoder();
    try  {
      byteMing = strMing.getBytes( "UTF8" );
      byteMi =  this .getEncCode(byteMing);
      strMi = base64en.encode(byteMi);
    }  catch  (Exception e) {
      e.printStackTrace();
    }  finally  {
      base64en =  null ;
      byteMing =  null ;
      byteMi =  null ;
    }
    return  strMi;
  }

  /**
   * 解密 以String密文输入,String明文输出
   * @param strMi               String密文
   * @return                    String明文
   */
  public  String getDesString(String strMi) {
    BASE64Decoder base64De =  new  BASE64Decoder();
    byte [] byteMing =  null ;
    byte [] byteMi =  null ;
    String strMing =  "" ;
    try  {
      byteMi = base64De.decodeBuffer(strMi);
      byteMing =  this .getDesCode(byteMi);
      strMing =  new  String(byteMing,  "UTF8" );
    }  catch  (Exception e) {
      e.printStackTrace();
    }  finally  {
      base64De =  null ;
      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;
  }

  //转化为16进制字符串
  public  static  String byte2hex( byte [] b){
      String hs= "" ;
      String stmp= "" ;
      for ( int  n= 0 ;n
          stmp=(java.lang.Integer.toHexString(b[n]& 0XFF ));
          if (stmp.length()== 1 )hs=hs+ "0" +stmp;
          else  hs=hs+stmp;
          if (n 1 ) hs=hs+ ":" ;
      }
      return  hs.toUpperCase();
}


  public  static  void  main(String args[]) {
     Des des= new  Des(); //实例化一个对像
     des.getKey( "aadd" ); //生成密匙

     String strEnc = des.getEncString( "明文" ); //加密字符串,返回String的密文
     System.out.println( "加密文:" +strEnc);

     String strDes = des.getDesString(strEnc); //把String 类型的密文解密
     System.out.println( "解密文:" +strDes);
  }
}