JS前台加密,java后台解密实现

    <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>  

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