Cryptographic auth can be used also on virtual links.

doc/bird.sgml

@@ -1390,7 +1390,7 @@ protocol ospf <name> {
 			wait <num>;
 			dead count <num>;
 			dead <num>;
-			authentication [none|simple];
+			authentication [none|simple|cryptographics];
 			password "<text>";
 		};
 	};