title: C# - Two-Factor Authentication (without ASP.NET Core Identity)
body: <p>Is it possible to implement a two-factor authentication without use ASP.NET Core Identity?</p>
  <p>I have my own login table and everything works fine with login + password + jwt, but my customer wants to put a extra security using a two-factor authentication via SMS or E-mail.</p>
  <p>I thought about Authy from Twilio but I don't understand if it is possible to do without ASP.NET Core Identity.</p>