Subject: Re: Kerberos: telnet to Solaris -> Bad encryption type
To: Johan Danielsson <email@example.com>
From: Steven M. Bellovin <firstname.lastname@example.org>
Date: 09/27/2005 09:14:31
In message <email@example.com>, Johan Danielsson writes:
>"Steven M. Bellovin" <firstname.lastname@example.org> writes:
>> Why do you say this? As far as I know, there are no generic attacks
>> against CFB, and the weakness of DES is (and always has been) against
>> brute-force key search, which 3DES defends against.
>Maybe I'm wrong. If the weakness of CFB lies only in the crypto used,
>then 3DES is a lot better. Also telnet doesn't implement any integrity
>by itself, and CFB doesn't help much either.
Lack of integrity-checking in a crypto protocol is indeed serious. For
telnet, it's' slightly worse for CFB than for CBC, but both are
seriously flawed against replay attacks.
--Steven M. Bellovin, http://www.cs.columbia.edu/~smb