Originally Posted by Viper-666

I don't think the XF Keys are cloneable. I have already testet this with a XHorse Key Tool the cloned keys don't work. Also I have read several times, that the transponders have a rolling code system.

I believe that I have found a way to create useful keys. But this is complicated and requires some special tools and soldering skills.
You have to desolder the processor of the Skreem module, read it and with this dump you can create the keys 1-8 with another program.
I already managed to clone the skreem with this method and now wait for my PCF7935 transponders to create a new key.
I'm not sure if the program I have now can read the keys correctly from the skreem dump but I know a program or tool which can do this. Unfortunately this costs about 1300 $