Subject: Re: Last Call: Telnet Authentication Option to Proposed Standard

From: [email-masked] (Johan Danielsson)
Date: 23 Nov 1999 14:21:19 +0100

The IESG <[email-masked]> writes:

> o Telnet Encryption: DES3 64 bit Cipher Feedback 
> 	<draft-altman-telnet-enc-des3-cfb-01.txt> 
> o Telnet Encryption: DES3 64 bit Output Feedback 
> 	<draft-altman-telnet-enc-des3-ofb-01.txt> 

Do these make sense at all? Do they provide any better security than
single des?

I haven't seen any discussion.

/Johan
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From: Jeffrey Altman <[email-masked]>
Date: Tue, 23 Nov 99 10:23:13 EST

> Jeffrey Altman <[email-masked]> writes:
> 
> > You are questioning the use of Triple DES but not the use of
> > CAST-128.
> 
> I'm questioning the use of DES3 in anything but EDE on outer CBC
> mode. There is a paper by Eli Biham about other combinations, which
> basically says that most of them are not much better than single DES.
> 
> Even though this paper doesn't talk about this specific use, it's not
> obvious that it's more secure to use DES3 to generate random numbers
> than it is to use single DES.
> 
> Has this case been analysed by anyone?
> 
> /Johan
> 

Thanks for explaining.  The answer is that I don't know.  I am not 
qualified to make that analysis.

    Jeffrey Altman * Sr.Software Designer * Kermit-95 for Win32 and OS/2
                 The Kermit Project * Columbia University
              612 West 115th St #716 * New York, NY * 10025
  http://www.kermit-project.org/k95.html * [email-masked]