簡單加密/解密方法包裝, 含encode(),decode(),md5()

簡單加密/解密方法包裝, 含encode(),decode(),md5() 

 發表日期：2004-07-30 作者：[轉貼] 出處：  

package steeven;

import java.security.*;

import javax.crypto.*;

public class Crypt {

  private static String Algorithm="DES"; //定義 加密算法,可用 DES,DESede,Blowfish

  static boolean debug = false;

  static{

    Security.addProvider(new com.sun.crypto.provider.SunJCE());

  }

  //生成密鑰, 注意此步驟時間比較長

  public static byte[] getKey() throws Exception{

    KeyGenerator keygen = KeyGenerator.getInstance(Algorithm);

    SecretKey deskey = keygen.generateKey();

    if (debug)

      System.out.println("生成密鑰:"+byte2hex(deskey.getEncoded()));

    return deskey.getEncoded();

  }

  //加密

  public static byte[] encode(byte[] input,byte[] key) throws Exception{

    SecretKey deskey = new javax.crypto.spec.SecretKeySpec(key,Algorithm);

    if (debug){

      System.out.println("加密前的二進串:"+byte2hex(input));

      System.out.println("加密前的字元串:"+new String(input));

    }

    Cipher c1 = Cipher.getInstance(Algorithm);

    c1.init(Cipher.ENCRYPT_MODE,deskey);

    byte[] cipherByte=c1.doFinal(input);

    if (debug)

      System.out.println("加密後的二進串:"+byte2hex(cipherByte));

    return cipherByte;

  }

  //解密

  public static byte[] decode(byte[] input,byte[] key) throws Exception{

    SecretKey deskey = new javax.crypto.spec.SecretKeySpec(key,Algorithm);

    if (debug)

      System.out.println("解密前的資訊:"+byte2hex(input));

    Cipher c1 = Cipher.getInstance(Algorithm);

    c1.init(Cipher.DECRYPT_MODE,deskey);

    byte[] clearByte=c1.doFinal(input);

    if (debug){

      System.out.println("解密後的二進串:"+byte2hex(clearByte));

      System.out.println("解密後的字元串:"+(new String(clearByte)));

    }

    return clearByte;

  }

  //md5()資訊摘要, 不可逆

  public static byte[] md5(byte[] input) throws Exception{

    java.security.MessageDigest alg=java.security.MessageDigest.getInstance("MD5"); //or "SHA-1"

    if (debug){

      System.out.println("摘要前的二進串:"+byte2hex(input));

      System.out.println("摘要前的字元串:"+new String(input));

    }

    alg.update(input);

    byte[] digest = alg.digest();

    if (debug)

      System.out.println("摘要後的二進串:"+byte2hex(digest));

    return digest;

  }

  //位元組碼轉換成16進制字元串

  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      }

    return hs.toUpperCase();

  }

  public static void main(String[] args) throws Exception{

    debug = true;

//    byte[] key = getKey();

    byte[] key = "好好學習".getBytes();

    decode(encode("測試加密".getBytes(),key),key);

    md5("測試加密".getBytes());

  }

}