明文暴露___JS前台加密,java后台解密实现

1.前台JS

 <script type="text/javascript">
     $(function() {
         $("#btn").click(function() {
             var username = encode64($("#username").val());  //对数据加密
             var password = encode64($("#password").val());
             $("#username").val(username);
             $("#password").val(password);
             document.fm.submit();  //fm为form表单name
         })
     })  

     // base64加密开始
     var keyStr = "ABCDEFGHIJKLMNOP" + "QRSTUVWXYZabcdef" + "ghijklmnopqrstuv"
             + "wxyz0123456789+/" + "=";  

     function encode64(input) {  

         var output = "";
         var chr1, chr2, chr3 = "";
         var enc1, enc2, enc3, enc4 = "";
         var i = 0;
         do {
             chr1 = input.charCodeAt(i++);
             chr2 = input.charCodeAt(i++);
             chr3 = input.charCodeAt(i++);
             enc1 = chr1 >> 2;
             enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
             enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
             enc4 = chr3 & 63;
             if (isNaN(chr2)) {
                 enc3 = enc4 = 64;
             } else if (isNaN(chr3)) {
                 enc4 = 64;
             }
             output = output + keyStr.charAt(enc1) + keyStr.charAt(enc2)
                     + keyStr.charAt(enc3) + keyStr.charAt(enc4);
             chr1 = chr2 = chr3 = "";
             enc1 = enc2 = enc3 = enc4 = "";
         } while (i < input.length);  

         return output;
     }
     // base64加密结束
 </script> 

2、后台java代码

 private static char[] base64EncodeChars = new char[] { 'A', 'B', 'C', 'D',
         'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q',
         'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
         'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q',
         'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3',
         '4', '5', '6', '7', '8', '9', '+', '/', };  

 private static byte[] base64DecodeChars = new byte[] { -1, -1, -1, -1, -1,
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
         -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59,
         60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
         10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1,
         -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,
         38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1,
         -1, -1 };  

 /**
  * 解密
  * @param str
  * @return
  */
 public static byte[] decode(String str) {
     byte[] data = str.getBytes();
     int len = data.length;
     ByteArrayOutputStream buf = new ByteArrayOutputStream(len);
     int i = 0;
     int b1, b2, b3, b4;  

     while (i < len) {
         do {
             b1 = base64DecodeChars[data[i++]];
         } while (i < len && b1 == -1);
         if (b1 == -1) {
             break;
         }  

         do {
             b2 = base64DecodeChars[data[i++]];
         } while (i < len && b2 == -1);
         if (b2 == -1) {
             break;
         }
         buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4)));  

         do {
             b3 = data[i++];
             if (b3 == 61) {
                 return buf.toByteArray();
             }
             b3 = base64DecodeChars[b3];
         } while (i < len && b3 == -1);
         if (b3 == -1) {
             break;
         }
         buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));  

         do {
             b4 = data[i++];
             if (b4 == 61) {
                 return buf.toByteArray();
             }
             b4 = base64DecodeChars[b4];
         } while (i < len && b4 == -1);
         if (b4 == -1) {
             break;
         }
         buf.write((int) (((b3 & 0x03) << 6) | b4));
     }
     return buf.toByteArray();
 }  

 System.out.println(new String(decode(username)));  // 使用decode()方法进行解密