[cfarm-users] Is RSA really insecure?

[Segher Boessenkool]

On Thu, Dec 14, 2023 at 01:22:28AM -0300, Alexandre Oliva via cfarm-users wrote:
> On Dec 13, 2023, Jacob Bachmeyer <jcb62281 at gmail.com> wrote:
> > This is a pet peeve of mine:  unless you have a citation for an actual
> > viable attack on RSA as used in SSH, or perhaps on the protocol SSH
> > uses for RSA-based authentication
> 
> AFAIK, ssh-rsa relies on SHA1 and SHA1 is weakening.  Labeling it as
> 'insecure', like I did, was probably an exaggeration, but there seems to
> be good reason to phase it out proactively rather than reactively.

Exactly.  And this wouldn't endanger your keys, in the worst case your
connections to these old machines could be eavesdropped, or very maybe
even taken over.  So enabling these older protocols for machines that
run older software and so do not support newer, better protocols should
be fine for almost everyone.

Maybe add a comment to your .ssh/config to that effect ;-)


Segher