Re: CVS commit: src/sys/netinet

["Steven M. Bellovin" <smb%research.att.com@localhost>]

In message <878yp1wm1h.fsf%snark.piermont.com@localhost>, "Perry E. Metzger" 
writes:
>
>David Laight <david%l8s.co.uk@localhost> writes:
>> - sequences where values are guaranteed not to be reproduced
>> - random values
>
>One way to do this is encrypting a counter with a 32 bit block cipher,
>but until a few minutes ago I was unaware of any. (Now I've learned of
>one on the cryptography mailing list.)

Right, but some uses for such things have stronger non-repitition 
requirements.  For example, the TCP initial sequence number shouldn't 
repeat for 2*maximum segment lifetime.  The IPid field shouldn't repeat 
for somewhat longer than the fragment lifetime on the receiving system.


                --Steve Bellovin, http://www.research.att.com/~smb