[2659] in cryptography@c2.net mail archive
Re: Chaffing & winnowing without overhead
daemon@ATHENA.MIT.EDU (Mordechai Ovits)
Mon May 11 21:00:45 1998
Date: Mon, 11 May 1998 15:06:41 -0400
From: "Mordechai Ovits" <movits@syndata.com>
To: "Jesús Cea Avión" <jcea@argo.es>
CC: coderpunks@toad.com, cypherpunks@toad.com, cryptography@c2.net,
hacking@argo.es, teleco-vigo@argo.es,
Lista PGP <MAIL-PGP@listserv.rediris.es>,
Lista Apedanica <apedanica@encomix.com>, cripto-foro@fi.upm.es
Jesús Cea Avión wrote:
> In the Rivest's paper you transmit, indeed, all the 2^n plaintexts for a
> n bit length };-).
Not so. In his paper (before the package tranform stuff), he had the following expansion.
Assuming a 32 bit serial number and a 160 bit MAC, n bits would expand to 388n.
This is because Ron is sending it out like this:
quote from http://theory.lcs.mit.edu/~rivest/chaffing.txt
>To make this clearer with an example, note that the adversary
>will see triples of the form:
> (1,0,351216)
> (1,1,895634)
> (2,0,452412)
> (2,1,534981)
> (3,0,639723)
> (3,1,905344)
> (4,0,321329)
> (4,1,978823)
> ...
>and so on.
Every bit is getting 2 32-bit serial numbers, its own complement, and 2 160-bit MACs.
a 10KB file would explode into a 3.789MB file.
Not too practical, eh? :-)
--
o Mordy Ovits
o Programmer / Cryptographer
o SynData Technologies Inc.
o Download A Free Copy Of Our Software At:
o http://www.syncrypt.com
