Re: New proposed solution to the QC biometric issue

[Stefan Santesson <stefan@xxxxxxxxxxx>]

Denis,

In general good suggestions but I oppose to the following general approach:

At 12:42 PM 4/15/99 +0200, Denis Pinkas wrote:
<snip>
>"In order to achieve a balance
>between these two opposite requirements the hash values of some
>additional attributes can be placed in a public key certificate."

As a general approach this would be a bad thing to do.

Most name attributes doesn't have enough name space for a hash to provide
any protection against exhaustive search for the originating data.

Say for example that you provide hash on names. It would not be to hard to
make an exhaustive search on frequent names and thereby find most of the
names through their hash.

The same with a social security number or a birth date. The name space are
in these cases tiny compared to the computing power of a single workstation.

So providing additional "hidden" attributes by providing their hash will
generally require some additional construct algorithm which prevents
exhaustive search (e.g. adding random data and/or combining several
attributes), and such logic is well beyond the scope of the QC work (As I
see it now).

/Stefan

-------------------------------------------------------------------
Stefan Santesson                <stefan@accurata.se>
Accurata Systemsäkerhet AB      http://www.accurata.se
Slagthuset                      Tel. +46-40 108588              
211 20  Malmö                   Fax. +46-40 150790              
Sweden                        Mobile +46-70 5247799

PGP fingerprint: 89BC 6C79 5B3D 591B 8547  1512 7D11 DBF4 528F 29A0
-------------------------------------------------------------------