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Date:      Mon, 03 Jun 1996 18:42:56 -0400
From:      He Who Urges Ampersands <arensb@cfar.UMD.EDU>
To:        "Mikael Karpberg" <karpen@sea.campus.luth.se>
Cc:        freebsd-security@freebsd.org
Subject:   Re: MD5 Crack code 
Message-ID:  <199606032242.SAA10718@glitnir.cfar.UMD.EDU>
In-Reply-To: Your message of "Mon, 03 Jun 1996 16:35:08 %2B0200." <199606031435.QAA06701@sea.campus.luth.se> 

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On Mon, 03 Jun 1996 16:35:08 +0200, karpen@sea.campus.luth.se wrote:
> > Personally I'd love to insist on Skey (or something like it). Seems to
> > me that simply building clients (FTP, telnet, MUA's, etc.) that are
> > "Skey aware" would go a long way. A separate Skey calculator is a
> > level of "complexity" that many naive users seem to balk at.
> 
> I'm not aware of how Skey works, I must say. Doesn't it require you to
> remember one time passwords or something? Seems like a hassle. Please
> feel free to correct me, since I'm surely a novice when it comes to that. :)

	No, you just have one password. The idea behind s/Key is to
avoid having clear-text passwords transmitted over an insecure
network.
	When you log in, the remote machine issues an s/Key challenge,
which includes the "sequence number:" the remote machine keeps track
of how many times you've successfully logged in.
	You then need to feed the s/Key challenge (including the
sequence number) and your secret password to a local s/Key calculator.
It then turns the whole thing into a one-time password, which you then
give to the remote machine.

	Ordinarily, you need a local s/Key calculator handy, or else
you need to print out a list of one-time passwords that you can carry
around on you. Yes, this is something of a hassle.
	One hack that we use, which I'd like to include in FreeBSD's
'rlogin' and/or 'telnet', is that, if you type '~@', and the last N
characters received from the remote end include an s/Key challenge,
then the *local* 'rlogin' will prompt you for a password and run the
s/Key calculator for you. In effect, instead of
	rlogin remotehost
	suspend
	key <sequence> <seed>
	<password>
	fg
	<s/Key password>
you only need to
	~@<password>

-- 
Andrew Arensburger, Systems guy         Center for Automation Research
arensb@cfar.umd.edu                     University of Maryland
	 If this isn't war, why is CNN massing on the border?



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