Markus Friedl wrote:
On Thu, Aug 21, 2003 at 09:10:13PM -0700, Frank Cusack wrote:Is there a security issue with turning an RSA1 key into an RSA key? One might want to do this, e.g., to move to protocol 2 without having to update authorized_keys files.in protocol 1 rsa keys are used for encryption, in protocol 2 they are used for signatures.
Markus--In protocol 2, the RSA public key verifies a signature, as in protocol 1, a RSA public key encrypts a token. I'm not sure, but the only difference between the two may very well be the source of the token being operated upon -- SSHv1 has the client generate random data; SSHv2 has the server generate and hash it. Either way, client + pubkey authenticates server + privkey.
I'm not saying it's safe to dual-purpose RSA; I'm just not entirely sure I've seen evidence it's dangerous to multipurpose the same RSA key. Have you seen any evidence to the contrary?
--Dan