c# - hiding a connection in a .dll

Question

I'm new to c#, but I need to change an existing program, by merely changing the connection string. The idea is to redirect the connection to a test database environment. I've found that the code uses a dll to create a connection to the server. I used Jetbrains Dotpeek to look inside the dll, but I could only see methods and functions, but nowhere could I see the connection detail to change it.

What ways are there of encrypting a connection string? Are there special files used generally for this, that I can look for?

To give more elaborate information:

In the normal code in the cs file, there is for example this:

var result = new LibSqlQuery(Db.ABC.ConnectionString, sql);
return result;

and Db is a method in a dll defined as following:

public static class Db
{
    private static Dictionary<string, LibDbConnection> _connections = new Dictionary<string, LibDbConnection>();

    private static LibDbConnection GetConnection(string connectionName)
    {
      lock (Db._connections)
      {
        if (!Db._connections.ContainsKey(connectionName))
          Db._connections.Add(connectionName, new LibDbConnection(connectionName));
      }
      return Db._connections[connectionName];
    }

    public static LibDbConnection ABC => Db.GetConnection("conABC");

    public static LibDbConnection CDE => Db.GetConnection("conCDE");
}

where ABC and CDE are database environments.

Answer 1

I found another config file, which had the connections. This can be closed now. Thank you.