[10663] in cryptography@c2.net mail archive
Re: ciphersaber-2 human memorable test vectors
daemon@ATHENA.MIT.EDU (Adam Back)
Fri Mar 29 20:41:58 2002
Date: Fri, 29 Mar 2002 23:02:44 +0000
From: Adam Back <adam@cypherspace.org>
To: Bill Frantz <frantz@pwpconsult.com>
Cc: cryptography@wasabisystems.com,
Anton Stiglic <stiglic@cs.mcgill.ca>
Message-ID: <20020329230244.A1548287@exeter.ac.uk>
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In-Reply-To: <v03110702b8ca90eac004@[165.247.205.5]>; from frantz@pwpconsult.com on Fri, Mar 29, 2002 at 01:49:30PM -0800
On Fri, Mar 29, 2002 at 01:49:30PM -0800, Bill Frantz wrote:
> At 10:15 AM -0800 3/26/02, Adam Back wrote:
> >In general purely human readable test vectors are not ideal as they
> >are 7 bit, and there have been cases where implementation errors or
> >related to the 7th bit (for example one blowfish implementation had
> >problems with signd / unsigned chars), but it is kind of an
> >interesting though experiment.
>
> If this issue seems to be a problem for a particular cypher, there are a
> couple of ways to try to solve it:
>
> * Compress out the eighth bit (requiring 10 characters for a 64 bit block
> cypher instead of 8).
That would work.
> * Remember a pattern of high order bits. Something like 11110000 would be
> relatively easy to remember, and would help mitigate signed vs. unsigned
> number problems on 32 bit machines.
No guarantees about what the rest of the test vector would look like
if you choose an easily rememberable high order bit set as the key
(which was where the blowfish problem arose if I recall). Or perhaps
you were suggesting ORing them into the otherwise 7 bit test vector
and having the additional constraint that the other outputs had the
same or equally memorable high bit pattern. That would be plausible.
Any takers on ciphersaber-2 test vectors which are also topical and
amusing english phrases?
Adam
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