var certData = NSData.FromArray(certBytes);
var options = new NSMutableDictionary
{
  ["passphrase"] = new NSString(authenticationContainer.Secret)
};
if (SecImportExport.ImportPkcs12(certData, options, out var items) != SecStatusCode.Success)
{
  return false;
}

var identityRef = items[0]["identity"];
var identity = new SecIdentity(identityRef.Handle);
var credential = new NSUrlCredential(identity, new[] {identity.Certificate}, NSUrlCredentialPersistence.ForSession);
return true;