title: Encrypt String in .NET Core
body: <p>I would like to encrypt a string in .NET Core using a key. I have a client / server scenario and would like to encrypt a string on the client, send it to the server and decrypt it. </p>
  
  <p>As .NET Core is still in a early stage (e.g. Rijndael is not yet available), what are my options? </p>