Simple string encryption in .NET and Javascript

Question

I\'m developing an ASP.NET MVC application in which I want to encrypt a short string on the server, using C#, and send it to the client-side.

Then on the client-side

Answer 1

It sounds like you want an obfuscation or encoding, not encryption. Base64 encoding should work well here. The result will look nothing like an email address, and the encoding process is fast.

In C#, you can use:

string emailAddress = "abc@example.com";
string encoded = Convert.ToBase64String(Encoding.UTF8.GetBytes(emailAddress));

And you can use this JavaScript function to decode it:

function Base64Decode(encoded) {
   var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
   var output = "";
   var chr1, chr2, chr3;
   var enc1, enc2, enc3, enc4;
   var i = 0;

   do {
      enc1 = keyStr.indexOf(encoded.charAt(i++));
      enc2 = keyStr.indexOf(encoded.charAt(i++));
      enc3 = keyStr.indexOf(encoded.charAt(i++));
      enc4 = keyStr.indexOf(encoded.charAt(i++));

      chr1 = (enc1 << 2) | (enc2 >> 4);
      chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
      chr3 = ((enc3 & 3) << 6) | enc4;

      output = output + String.fromCharCode(chr1);

      if (enc3 != 64) {
         output = output + String.fromCharCode(chr2);
      }
      if (enc4 != 64) {
         output = output + String.fromCharCode(chr3);
      }
   } while (i < encoded.length);

   return output;
}

The C# application encodes the string abc@example.com into YWJjQGV4YW1wbGUuY29t, and the JavaScript version will decode YWJjQGV4YW1wbGUuY29t back into abc@example.com.