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MD5 轉碼 實現加密解密

 /***
     * MD5加碼 生成32位md5碼
     */ 
    public static String string2MD5(String inStr){ 
        MessageDigest md5 = null; 
        try{ 
            md5 = MessageDigest.getInstance("MD5"); 
        }catch (Exception e){ 
            System.out.println(e.toString()); 
            e.printStackTrace(); 
            return ""; 
        } 
        char[] charArray = inStr.toCharArray(); 
        byte[] byteArray = new byte[charArray.length]; 
 
        for (int i = 0; i < charArray.length; i++) 
            byteArray[i] = (byte) charArray[i]; 
        byte[] md5Bytes = md5.digest(byteArray); 
        StringBuffer hexValue = new StringBuffer(); 
        for (int i = 0; i < md5Bytes.length; i++){ 
            int val = ((int) md5Bytes[i]) & 0xff; 
            if (val < 16) 
                hexValue.append("0"); 
            hexValue.append(Integer.toHexString(val)); 
        } 
        return hexValue.toString(); 
 
    } 
 
    /**
     * 加密解密演算法 執行一次加密,兩次解密
     */  
    public static String convertMD5(String inStr){ 
 
        char[] a = inStr.toCharArray(); 
        for (int i = 0; i < a.length; i++){ 
            a[i] = (char) (a[i] ^ 't'); 
        } 
        String s = new String(a); 
        return s; 
 
    } 
 
    // 測試主函式 
    public static void main(String args[]) { 
        String s = new String("123456"); 
        System.out.println("原始:" + s); 
        System.out.println("MD5後:" + string2MD5(s)); 
        System.out.println("加密的:" + convertMD5(s)); 
        System.out.println("解密的:" + convertMD5(convertMD5(s))); 
        System.out.println(MD5.digest2Str("a"));
 
    }