Re: [TLS] TLS, PKI,

[Yoav Nir <[e-mail]>]

On Jul 14, 2010, at 2:56 PM, Peter Gutmann wrote:

> Bruno Harbulot <[e-mail]> writes:
> 
>> I wonder how many people really check the fingerprint of the SSH server key
>> when they connect to a server they haven't connected to before.
> 
> I don't know about connecting to new servers, but if the fingerprint changes
> when connecting to an existing server then the same number check it as the
> number who perform out-of-band verification of certs when they change: Zero.
> 
> (I did a survey of two large .edus as groundwork for a paper I was thinking of
> writing and needed to know the base rate for a fuzzy-fingerprint attack, which
> allows you to spoof SSH server fingerprints unless the user methodically
> verifies all 160 bits of the fingerprint.  It was zero, which meant that the
> fuzzy-fingerprint attack couldn't be any worse than that.  This lead to a
> proposed paper with the title "Do users check SSH fingerprints to defeat MITM
> attacks?" and an abstract of "No", which I felt was brief and to the point).
> 
> This result represents good news for both the SSL/TLS PKI camps and the SSH
> key-continuity camps, since SSH advocates can rejoice over the fact that the
> expensive PKI-based approach is no better than the SSH one, while PKI
> advocates can rest assured that their solution is no less secure than the SSH
> one.

But it's kind of sad for the geek-supremacists, who would have liked to believe that geeks do security better than other people.