Recover query string with "+" character

Question

I have in my controller, a method where I take a Query String, I decrypt it and use the data in my query. However, when the encrypted value has a +, he is not recovered by Request.QueryString. Soon I get an error when trying to decrypt.

Follow my controller:

 public ActionResult 
       {

            //Recebe a string Criptografada
            string param = Request.QueryString["param"];// Nesta Parte o sinal de + não é recuperado
            string nome = HttpUtility.UrlDecode(param);

            //Instancia obj da DLL
            Criptografia cr = new Criptografia();
            //Descriptografa a string
            string nomeDescrypt = cr.Decrypt(nome);// recebo o erro

            //Separa a string por meio do "|"
            string[] stringSeparators = new string[] { "|" };
            var result = nomeDescrypt.Split(stringSeparators, StringSplitOptions.None);

            //Converte para o tipo de dado correto
            var matricula = Convert.ToInt32(result[0]);
            var contrato = Convert.ToInt32(result[1]);

            var usuarios = usuarioRepository.Lista.Where(r => r.CdMatricula == matriculaUser && r.SqContrato == contratoUser).FirstOrDefault();

            return View();
        }

Example of parameter passed: ./?param=kmFxK8ID3ç+Zdggbqn9oja==
What is recovered: ./?param=kmFxK8ID3ç Zdggbqn9oja==

The sign of + vanish, and there’s a space in place.

Answer 1

+ has a semantic meaning in the query string. It is used to represent space.

If you want to get the literal + in your query string, you need to change the + by the Percent-encoding of it: %2B

Example: . /? param=foo%2Bbar
In your code-Behind will return: foo+bar

Another way is to replace the + for %2B via programming:

string param = Request.QueryString["param"];
string nome = param != null ? HttpUtility.UrlDecode(param.Replace(" ", "%2B")) : "";

Answer 2

You can use the method replace() to replace this blank!