Encode strings with JavaScript and Asp.net

The. NET system. Text. asciiencoding and system. bitconvertor classes work together to encrypt strings on the server. The client uses JavaScript to decrypt strings. The Code is as follows:

<Script language = "JavaScript">

/*

========================================================== ============================

This function helps protect the email address from the edevil spam-bots

That Scan Web pages for useful data such as (email addresses ).

Instead of using the data directly, the encoded value is stored in

HTML and decoded when required.

========================================================== ============================

*/

Function decode (serverencoded)

{

// The serverencoded parameter is a string that contains the encoded data.

// Each character in the serverencoded parameter has been converted

// A two digit number (hex/base16). This function converts

// Series of numbers back into the normal form and returns

// Decoded string to the client

 

// Holds the decoded string

VaR res = "";

 

// Go through and decode the full input server encoded string

For (I = 0; I <serverencoded. length ;)

{

// Holds each letter (2 digits)

VaR letter = "";

Letter = serverencoded. charat (I) + serverencoded. charat (I + 1)

 

// Build the real decoded Value

Res + = string. fromcharcode (parseint (letter, 16 ));

I + = 2;

}

// Return the new decoded string to allow it to be rendered to screen

Return res;

}

 

 

/*

========================================================== ============================

This function gets a reference to the server encrypted string and

Then decrypts this using the decode () function and sets

Txtdecrypted value to the value return by the decode () function

========================================================== ============================

*/

Function getemailanddecode (){

// Get the table <a class = IAS style = "font-weight: normal; font-size: 100%; padding-bottom: 1px; color: darkgreen; border-bottom: darkgreen 0.07em solid; Background-color: transparent; text-Decoration: underline "href =" # "target = _ blank itxtdid =" 3146774 "> element </a>

VaR txtsvrencr = Document. getelementbyid ('txtserverencrypted ');

VaR txtjsdecr = Document. getelementbyid ('txtdecrypted ');

Txtjsdecr. value = decode (txtsvrencr. value );

VaR txtalltog = Document. getelementbyid ('txtalltogether ');

Txtalltog. value = decode (txtalltog. value );

}

</SCRIPT>

 

 

Public partial class _ default: system. Web. UI. Page

{

Protected void page_load (Object sender, eventargs E)

{

# Region email encryption

// If Javascript is enabled do the Encoding

If (request. browser. Javascript)

{

// Do the encryption using the raw email

Txtserverencrypted. Text = system. bitconverter. tostring (

System. Text. asciiencoding. ASCII. getbytes (

(Txtrawemail. Text). Replace ("-","");

 

// Do the encryption using the raw email

Txtalltogether. Text = system. bitconverter. tostring (

System. Text. asciiencoding. ASCII. getbytes (

(Txtrawemail. Text). Replace ("-","");

}

Else

{

// Couldnt find JavaScript so just use normal email

Txtserverencrypted. Text = txtrawemail. text;

Txtalltogether. Text = txtrawemail. text;

}

# Endregion

}

}

 

For details, see simple web based obfuscation.