Date: Mon, 08 Mar 2010 14:19:40 -0500 From: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org> To: Angelin Lalev <lalev.angelin@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: [OT] ssh security Message-ID: <44y6i239kj.fsf@be-well.ilk.org> In-Reply-To: <532b03711003071328n57042980gf5520f40dcc73950@mail.gmail.com> (Angelin Lalev's message of "Sun, 7 Mar 2010 23:28:58 %2B0200") References: <532b03711003071325j9ab3c98u703b31abdc7ea8fe@mail.gmail.com> <532b03711003071328n57042980gf5520f40dcc73950@mail.gmail.com>
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Angelin Lalev <lalev.angelin@gmail.com> writes: ;2~> On Sun, Mar 7, 2010 at 11:25 PM, Angelin Lalev <lalev.angelin@gmail.com> wrote: >> Greetings, >> >> I'm doing some research into ssh and its underlying cryptographic >> methods and I have questions. I don't know whom else to ask and humbly >> ask for forgiveness if I'm way OT. >> >> So, SSH uses algorithms like ssh-dss or ssh-rsa to do key exchange. >> These algorithms can defeat any attempts on eavesdropping, but cannot >> defeat man-in-the-middle attacks. To defeat them, some pre-shared >> information is needed - key fingerprint. >> >> If hypothetically someone uses instead of the plain text >> authentication some challenge-response scheme, based on user's >> password or even a hash of user's password would ssh be able to avoid >> the need the user to have key fingerprints of the server prior the >> first connection? >> > > To clarify, we as users anyway do have shared secret with the server > and that's the authentication password why we could not use that > instead of or in addition to a key fingerprint? Because we don't want to give an attacker access to a shared secret if we can verify host identity with a public key first. -- Lowell Gilbert, embedded/networking software engineer, Boston area http://be-well.ilk.org/~lowell/
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