From owner-freebsd-questions@FreeBSD.ORG Mon Mar 8 19:19:43 2010 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 16A05106564A for ; Mon, 8 Mar 2010 19:19:43 +0000 (UTC) (envelope-from freebsd-questions-local@be-well.ilk.org) Received: from mail2.sea5.speakeasy.net (mail2.sea5.speakeasy.net [69.17.117.4]) by mx1.freebsd.org (Postfix) with ESMTP id E4A0C8FC21 for ; Mon, 8 Mar 2010 19:19:42 +0000 (UTC) Received: (qmail 25892 invoked from network); 8 Mar 2010 19:19:42 -0000 Received: from dsl092-078-145.bos1.dsl.speakeasy.net (HELO be-well.ilk.org) ([66.92.78.145]) (envelope-sender ) by mail2.sea5.speakeasy.net (qmail-ldap-1.03) with SMTP for ; 8 Mar 2010 19:19:42 -0000 Received: by be-well.ilk.org (Postfix, from userid 1147) id A20B250883; Mon, 8 Mar 2010 14:19:40 -0500 (EST) From: Lowell Gilbert To: Angelin Lalev References: <532b03711003071325j9ab3c98u703b31abdc7ea8fe@mail.gmail.com> <532b03711003071328n57042980gf5520f40dcc73950@mail.gmail.com> Date: Mon, 08 Mar 2010 14:19:40 -0500 In-Reply-To: <532b03711003071328n57042980gf5520f40dcc73950@mail.gmail.com> (Angelin Lalev's message of "Sun, 7 Mar 2010 23:28:58 +0200") Message-ID: <44y6i239kj.fsf@be-well.ilk.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (berkeley-unix) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: freebsd-questions@freebsd.org Subject: Re: [OT] ssh security X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Mar 2010 19:19:43 -0000 Angelin Lalev writes: ;2~> On Sun, Mar 7, 2010 at 11:25 PM, Angelin Lalev 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/