[18067] in cryptography@c2.net mail archive
Re: Query about hash function capability
daemon@ATHENA.MIT.EDU (Victor Duchovni)
Thu Aug 4 16:23:29 2005
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Thu, 4 Aug 2005 10:03:01 -0400
From: Victor Duchovni <Victor.Duchovni@MorganStanley.com>
To: cryptography@metzdowd.com
Mail-Followup-To: cryptography@metzdowd.com
In-Reply-To: <42F183B7.6090606@partow.net>
On Thu, Aug 04, 2005 at 12:55:51PM +1000, Arash Partow wrote:
> Hi all,
>
> My question relates to hash functions in general and not specifically
> cryptographic hashes. I was wondering if there exists a group of hash
> function(s) that will return an identical result for sequentially
> similar yet rotate/shift wise dissimilar input:
>
> ie: input1 : abcdefg -> h(abcdefg) = 123
> input2 : gabcdef -> h(gabcdef) = 123
> input3 : fgabcde -> h(fgabcde) = 123
>
Sure, just pick the lexicographically first cycle and hash
that. This is an invariant of all cyclic permutations of the
string.
epermut -> h(epermut)
ermutep -> h(epermut)
muteper -> h(epermut)
permute -> h(epermut)
rmutepe -> h(epermut)
tepermu -> h(epermut)
uteperm -> h(epermut)
More generally given any automorphism group on the input strings, hashing
the lexicographically smallest member of the orbit of an input string
under the group gives a hash that is invariant under the group operation.
--
/"\ ASCII RIBBON NOTICE: If received in error,
\ / CAMPAIGN Victor Duchovni please destroy and notify
X AGAINST IT Security, sender. Sender does not waive
/ \ HTML MAIL Morgan Stanley confidentiality or privilege,
and use is prohibited.
---------------------------------------------------------------------
The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo@metzdowd.com
