Chapter 4 Query String

sandeepvin2 · October 16th, 2009, 03:51 PM

Hi

I am trying to implement encryption & decryption of query string following the steps as discussed in chapter 4 but the only difference is in the book only one value is encrypted & decrypted while in my case I am using 3 values.Encryption part is working fine but when I am trying to decrypt to get the query values I am getting an error which says

Invalid character in a Base-64 string.

Here is code for Encryption :

Code:

Dim collection As New NameValueCollection
            collection = System.Web.HttpUtility.ParseQueryString("Value=" + Name + "&PosNbr=" + PosNbr + "&TrackAppID=" + 34)
EncryptQueryString(collection)

when I try to decrypt I am getting the above error

Any help would be appreciated.

Corsair · October 19th, 2009, 02:05 PM

At a glance (without the book handy or source code handy), might it have something to do with the value you're encrypting, and not the decryption?

Looking at the code you pasted, I noticed you have a 34 (as a literal number) at the end of the argument passed into ParseQueryString. ParseQueryString expects a string - so I'm curious as to how you even got the code to run? I would have expected a compile error because of the 34....

Tim

kalel_4444 · October 21st, 2009, 12:39 PM

I found myself needing to encrypt/decrypt multiple querystring parameters quite often so I created a simple method that will decrypt the values and set them to strings, maybe this will help.
Remember, as Corsair commented, you must convert your integers to strings before encrypting.

// Here's the method (I put this in my BasePage so all pages have access to this).

Code:

public string GetDecryptedValue(string queryString)
{
   // Decrypt the query string
   NameValueCollection collection = DecryptQueryString(Request.QueryString.ToString());

   if (collection == null)
   {
      return null;
   }
   else
   {
      // Get string value
      string value = collection[queryString];

      if (string.IsNullOrEmpty(value))
      {
         return null;
      }
      else
      {
         return value;
      }
   }
}

// Here's a sample of using it.

Code:

// Query string values
string field1 = "value1";
string field2 = "value2";
string field3 = "value3";

// Encrypt the query strings
string Url = "page.aspx" + EncryptQueryString("f1=" + field1 + "&f2=" + field2 + "&f3=" + field3);

// Decrypt query strings
string field1 = GetDecryptedValue("f1");
string field2 = GetDecryptedValue("f2");
string field3 = GetDecryptedValue("f3");

Hope this helps,
Ronnie

ZeroFactorial · October 26th, 2009, 12:16 PM

Kalel,

I think you provided a very usable and alternative solution to the problem at hand. Much appreciated.

ZeroFactorial · October 26th, 2009, 12:22 PM

Kalel,

I think you provided a very usable and alternative solution to the problem at hand. Much appreciated.