Query about hash function capability

[Ian Clelland]

On Aug 3, 2005, at 7:55 PM, Arash Partow wrote:
> 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
>
> Here a,b,c,d,e,f,g represent symbols (ie: groups of bits with 
> equivalent
> group sizes etc...)

Why not just include a canonicalization step at the beginning of the
hash that is designed to ignore rotation?

For example, if you can define an ordering on the set of possible 
inputs to the hash, then you can rotate any input to the point where it 
is the "smallest" (or "largest") that it can be, and then hash *that* 
value.

Ian Clelland
<ian at veryfresh.com>


---------------------------------------------------------------------
The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo at metzdowd.com