App.config how to use`Connectionstring` encrypted

Question

In my app.config I have a section that for my String connecting:

 </configSections>
<connectionStrings>
    <add name="Azure.Onee" connectionString="Server=tcp:tps****.database.windows.net,1433;Data Source=tps****.database.windows.net;Initial Catalog=Onee;Persist Security Info=False;User ID=*****;Password=*****;MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=False;Connection Timeout=30" providerName="System.Data.SqlClient" />
</connectionStrings>

So I encrypted the section using the aspnet_regiis -pef, obtained as a result:

 <connectionStrings configProtectionProvider="RsaProtectedConfigurationProvider">
    <EncryptedData Type="http://www.w3.org/2001/04/xmlenc#Element"
        xmlns="http://www.w3.org/2001/04/xmlenc#">
        <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#tripledes-cbc" />
        <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">
            <EncryptedKey xmlns="http://www.w3.org/2001/04/xmlenc#">
                <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-1_5" />
                <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">
                    <KeyName>Rsa Key</KeyName>
                </KeyInfo>
                <CipherData>
                    <CipherValue>Z3lLfHojiPPq+ACyP3o0nM/XdwDVj2jsDIMwER/xT6gxR7qzBgJPJIb7kpaZIaUJwQQjlV9fnmsNlpOM0dFrH+8J2Z4tpYM5mIcDMaJjW/dIXwXvEXdk7ESgaKSbpPgHOElvRMwQgs5LSWVjdqpP9G39StgoGoeTKlaIi7CXeSo=</CipherValue>
                </CipherData>
            </EncryptedKey>
        </KeyInfo>
        <CipherData>
            <CipherValue>z0dsujvZ7MffBHfNj12d+TYHHbcvdW84vCrZKt0ldps=</CipherValue>
        </CipherData>
    </EncryptedData>
</connectionStrings>

Well, now how do I use to recover the connectionStrings to open the connection to my database?

To make the connection I’m doing so:

 private void simpleButton1_Click(object sender, EventArgs e)
    {
        string Usuario = textBox2.Text, Password = textBox1.Text;

        SqlConnection sqlconn = new SqlConnection(ConfigurationManager.ConnectionStrings["Azure.Onee"].ConnectionString);

        if (Usuario != string.Empty && Password != string.Empty)
        {
            try
            {
                consql._sql = @"SELECT id_usu FROM login WHERE usuario = @usuario AND password = @password";

                SqlCommand cmd = new SqlCommand(consql._sql, sqlconn);

                cmd.Parameters.Add("@usuario", SqlDbType.VarChar).Value = Usuario;
                cmd.Parameters.Add("@password", SqlDbType.VarChar).Value = Password;

                sqlconn.Open();

                // etc..
            }
            catch (Exception)
            {

            }
            finally
            {
                sqlconn.Close();
            }
        }

When trying to run, the error is returned:

I tried to run only with ConfigurationManager.ConnectionStrings without the Dice, here it neither compiles:

With the help of our colleague Gypsy, where he suggested to use the index 0, he passes, but this bringing a String totally different from String original:

Answer 1

As I said in comment, use instead of the name of Connection string:

SqlConnection sqlconn = new SqlConnection(ConfigurationManager.ConnectionStrings[1].Conn‌​ectionString);

In cryptography, the name of Connection string gets lost.

Care also when encrypting projects whose Web.config has been Connection strings developmental.

The configuration file name needs to be Web.config, and not App.config. After encryption you can change it if you want.