title: How to use RSA in .net Core
body: <p>I try to encrypt a file with <code>RSA</code>, but it don't have the <code>toXmlString()</code> and <code>fromXmlString</code> method. how to use <code>RSA</code> class in .net core ?
  And I want to encrypt with private key and decrypt with public key ,so others can only read this file but can't generate this file ， Is that possible ?</p>