How to use publickey from x509 certificate?

[Tanja Wittke]

Hello,

I have the following problem: I want to use publickey authentication by 
using the publickey of a x509 certificate stored on a java card. I can 
already extract the publickey of the certificate and write it into a 
file. The problem i have is that i don't know how to convert the 
certificate's publickey into an rsa publickey format that openssh will 
accept. 

Does anybody have a hint for me?

Thank you in advance,

tawi