Re: Chaffing & winnowing without overhead

["Mordechai Ovits" <movits@syndata.com>]

Jes�s Cea Avi�n 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
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