des加密与解密

package cn.fulong.ccf.common;

import java.io.UnsupportedEncodingException;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.KeySpec;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

public class DesEncrypter {
  Cipher ecipher;
  Cipher dcipher;

  // 8-byte Salt
  byte[] salt = {
      (byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32,
      (byte) 0x56, (byte) 0x35, (byte) 0xE3, (byte) 0x03
  };

  // Iteration count
  int iterationCount = 19;

  public DesEncrypter(String passPhrase) {
    try {
      // Create the key
      KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt,
                                       iterationCount);
      SecretKey key = SecretKeyFactory.getInstance(
          "PBEWithMD5AndDES").generateSecret(keySpec);
      ecipher = Cipher.getInstance(key.getAlgorithm());
      dcipher = Cipher.getInstance(key.getAlgorithm());

      // Prepare the parameter to the ciphers
      AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt,
          iterationCount);

      // Create the ciphers
      ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
      dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
    }
    catch (java.security.InvalidAlgorithmParameterException e) {
    }
    catch (java.security.spec.InvalidKeySpecException e) {
    }
    catch (javax.crypto.NoSuchPaddingException e) {
    }
    catch (java.security.NoSuchAlgorithmException e) {
    }
    catch (java.security.InvalidKeyException e) {
    }
  }

  public String encrypt(String str) {
    try {
      // Encode the string into bytes using utf-8
      byte[] utf8 = str.getBytes("UTF8");

      // Encrypt
      byte[] enc = ecipher.doFinal(utf8);

      // Encode bytes to base64 to get a string
      return new sun.misc.BASE64Encoder().encode(enc);
    }
    catch (javax.crypto.BadPaddingException e) {
    }
    catch (IllegalBlockSizeException e) {
    }
    catch (UnsupportedEncodingException e) {
    }
    catch (java.io.IOException e) {
    }
    return null;
  }

  public String decrypt(String str) {
    try {
      // Decode base64 to get bytes
      byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);

      // Decrypt
      byte[] utf8 = dcipher.doFinal(dec);

      // Decode using utf-8
      return new String(utf8, "UTF8");
    }
    catch (javax.crypto.BadPaddingException e) {
    }
    catch (IllegalBlockSizeException e) {
    }
    catch (UnsupportedEncodingException e) {
    }
    catch (java.io.IOException e) {
    }
    return null;
  }

    public static double multi(long n) {
        if (n == 0) {
            return 1;
        } else {
            return  n * multi(n - 1);
        }
    }

    public static void main(String arg[]) {
     /*
      * 解密
      */
                String in="gAPYzh+OfUk=";
                DesEncrypter desin=new DesEncrypter("fulong");
                System.out.println(desin.decrypt(in));
               
        /*
         * 加密
         */
                String out = "fulong";
                DesEncrypter desout = new DesEncrypter("fulong");
                System.out.println(desout.encrypt(out));
     //System.out.print(multi(3));
      } 
}