[465] in cryptography@c2.net mail archive
Re: How bad is this?
daemon@ATHENA.MIT.EDU (Gary Howland)
Wed Apr 2 11:15:21 1997
To: perry@piermont.com
cc: cryptography@c2.net
In-reply-to: Your message of "Tue, 01 Apr 1997 23:58:09 CDT."
<199704020458.XAA10416@jekyll.piermont.com>
Date: Wed, 02 Apr 1997 15:03:27 +0200
From: Gary Howland <gary@systemics.com>
>
> Colin Plumb writes:
> > I've been trying to come up with a very fast, and not necessarily
> > very secure hash function for TCP initial sequence number selection.
> > (That means fast when *not* in an inner loop and doesn't thrash the cache.)
>
> I don't understand why this is necessary. Given how slow TCP initial
> handshakes are, and how (relatively) infrequent, I would guess that
> this wouldn't improve performance in any noticeable way, and would
> lower security...
Also bear in mind that SHA produces 20 bytes - good enough for 5 sequence
numbers.
An alternative might be to use a fast cipher, such as blowfish or RC4.
Gary
