Fwd: [Help-gnutls] Re: Authentication during Handshake

Nikos Mavrogiannopoulos nmav at gnutls.org
Tue May 20 01:53:10 CEST 2008

On Mon, May 19, 2008 at 11:38 PM, Rainer Gerhards <rgerhards at gmail.com> wrote:
> Hi Simon,
> I am working on both the client and server sides.
> What gives me most problems is the fingerprint authentication. In
> essence, each peer has a list of valid (remote peer's) certificate
> fingerprints. If the actual cert's fingerprint is in this list, the
> remote peer is succesfully authenticated. this is an alternate auth
> mode that does not require pki.

Actually this is a hack. As far as I remember there was no standard
way to fingerprint a certificate. MD5 was widely used for this but it
is broken now.

The alternative modes of TLS/SSL that do not require PKI are TLS-SRP
(rfc5054) and TLS-PSK (preshared keys - rfc 4279). These are the
straightforward ways to use TLS without PKI (certificates). Then it is
obvious to everybody how to perform the TLS handshake - if the shared
keys do not match it fails.  Gnutls supports both of these modes.

Please suggest these to the authors of the protocol you're referencing.


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