[14307] in Cypherpunks
Re: (fwd) Re: NSA Helped Yeltsin Foil 1991 Coup
daemon@ATHENA.MIT.EDU (Eli Brandt)
Fri May 27 16:00:20 1994
To: cypherpunks list <cypherpunks@toad.com>
Date: Fri, 27 May 94 12:55:36 PDT
From: Eli Brandt <ebrandt@jarthur.cs.hmc.edu>
In-Reply-To: <9405271908.AA09401@snark.imsi.com>; from "Perry E. Metzger" at May 27, 94 3:08 pm
> From: "Perry E. Metzger" <perry@imsi.com>
> > If you suspect that some of the non DOD/NSA cyphers might be broken,
> > but you are not ready to employ one-time-pads, then you should
> > threshold you mesages into N parts so that all N are needed to recover
> > the original. Then encrypt each part under a different cypher.
>
> Its far simpler to encrypt your message with multiple systems, one
> after another, than to break it up in the manner you suggest, and the
> security is in fact better that way than in the manner you suggest.
Why? If you XOR-split the message and encrypt each mask differently,
you are /guaranteed/ that all of the encryption methods must be
broken to retrieve the original. If you use repeated encryption,
this is much harder to prove, and not always true. There's a result
that if you choose the first cipher unwisely, you're hosed no matter
what you do on top of it.
Eli ebrandt@hmc.edu
