Julien Lafaye wrote:
> Marshall wrote:
>
>> I don't see any obvious reason why a digital signature algorithm
>> should
>> much care what the payload is. If not, then the question devolves to
>> what format to represent a database in, and what cryptographic hash
>> to use. Any reason not to just export the database in some native
>> text format?
>
> My problem with that but perhaps it would seem like a researcher problem is
> the following. A relational table should be invariant to a reordering of
> the tuples and/or the attributes. The signature algorithm should reflect
> this and I was wondering whether such an algorithm exists.
It seems to me improbable that such an algorithm exists (or even could
exist). Hash functions are intentionally very sensitive to the order in
which the data is presented (so as to detect any changes in the input
data). Using orthodox technology, then, you would be dependent on some
specific order for both the tuples within a relation and the attributes
within a tuple, not to mention some sequence for the relations in the
database.
--
Jonathan Leffler #include <disclaimer.h>
Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com
Guardian of DBD::Informix v2007.0226 -- http://dbi.perl.org/
Received on Thu Apr 19 2007 - 23:27:40 CDT
