How to md5 encrypted URL，do Persistence。

iRules can persist on any string. As long as its the same string each time for the same server then yes, you can do it.

Yes, it can absolutely do that, both the md5 hashing (md5 isn't really encryption, let's be honest) and the persistence portion. Is there anything in particular you want to persist on? Some portion of the URI? Or are you looking to hash the entirety of the URL and persist based on that info? That seems rather broad, but who am I to judge? ;)