title: SecKeyRawSign in MacOS not available
body: <p>I want to use the function SeckeyRawSign for signing a CSR in a MACOS application. How can I use this funcion to sign. 
  When I use the code in a iOS application, it works fine. 
  I use the code of <a href="https://github.com/ateska/ios-csr" rel="nofollow noreferrer">https://github.com/ateska/ios-csr</a></p>