Other Directory Sites: SeekWonder | Directory Owners Forum
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:16:18 ADT
Paul H. Merrill (paulmerrill@acm.org)
Thu, 26 Mar 1998 20:09:03 -0800
The primary problem with the "both bits together" technique is that you
have left the concept of non-encryption behind and have only a terribly
wasteful traffic flow.
The original concept was to have a system that left noone to be pointed
at as the Dread Encrypter.
PHM
proff@iq.org wrote:
>
> > Wouldn't winnowing and chaffing be worthless if your adversary had
> > access to the entire message stream.
> >
> > Postulate: Given that Charles has access to all message traffic
> > between Bob and Alice, by recombination of packets with unique
> > serial numbers, and the ability to recognize the full message (which
> > would be easier with a packaged message) the problem reduces to finding
> > the combinatorial set of packets and testing each resulting 'message.'
> >
> > Given the abilities of an even moderately powerful machine, it would
> > seem that unless the total chaff and wheat exceeded something on the
> > order of 100mbytes the message could be recovered in a relatively short
> > time.
> >
> > What am I missing?
> > --Chuck
>
> Suppose the wheat/chaff bits are equal, that is there is as much wheat
> as chaff. To ensure secure operation, the chaff bits should be chosen
> to be the inverse of the wheat bits, and 0 bits should always come first
> in the packet stream - that is it should not be possible to predict
> wheat or chaff based on packet order (the compression schemes I and
> other people outlined do away with this issue altogether, because
> wheat and chaff are effectively "in" the same packet/mac).
>
> Imagine the wheat/chaff bits are actually green/red beads and you
> are threading a necklace. The goal for both attacker and legitmate
> receiver is to end up with a necklace of only Green beads (although,
> because of the parameters of this example, an entirely Red necklace
> will server you just as well, being the xor of the Green necklace).
> At each step there are two choises. Red or Green. The legitimate
> receiver can tell Red from Green, because they have a pair of
> special filters for their sun-glasses - the MAC key. The attacker
> has no such aid (trapdoor) and is effectively colour-blind. The
> attacker will end up with a necklace of randomly mixed Red and
> Green beads, because they were unable to distinguist one from the
> other.
>
> Cheers,
> Julian.
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:16:18 ADT