Management of signature keys for government

[Brian Gladman]

-----Original Message-----
From: Markus Kuhn <Markus.Kuhn@cl.cam.ac.uk>
To: ukcrypto@maillist.ox.ac.uk <ukcrypto@maillist.ox.ac.uk>
Date: 01 March 1998 16:04
Subject: Re: Management of signature keys for government


>Brian Gladman wrote on 1998-03-01 13:35 UTC:
>> Markus Kuhn <Markus.Kuhn@cl.cam.ac.uk> wrote:
>> >I hope this makes clear that in-card key generation does not
>> >make it unnecessary to include the personalization facilities into the
>> >trusted computing base.
>>
>> It seems so and this makes smartcards an inadequate vehicle for really
good
>> security at the moment.  For some defence applications in which I have
been
>> involved we had to adopt the PCMCIA card format for just this reason.
>
>This is not the issue. I am very well aware that EEPROM-based smartcards
>provide only a medium level of tamper-resistance and that state-of-the-art
>miniature tamper-resistant modules such as say the DalSemi DS1954
CryptoButton
>or the various IBM security modules are based on battery buffered SRAM
>combined with a whole range of alarm zeroisation and anti-tampering
features
>that go far beyond of what smartcard processor manufacturers do today
><http://www.cl.cam.ac.uk/~mgk25/tamper.pdf>.
>
>You have to realize that these tamper-resistance feature work *against* you
>in an in-module signature key generation scheme: If the device that
generates
>your key is ultra-tamper-resistant, then you have no way of ensuring that
the
>algorithms applied are sound, most notably that the key generator has not
been
>tampered with. It is feasible to reverse engineer smartcards (cost in the
>order of 10^4 USD per processor type) and these capabilities could be
>used for sample quality control of a manufacturer's output. This would
>not be possible any more with modern high-grade tamper-resistant modules
that
>not even government labs can open. Tamper-resistance and quality assurance
>(including security evaluation) seem unfortunately to be conflicting
>design goals.


Hey, Markus, I didn't even mention tamper resistance and this was not the
reason why we used the PCMCIA format - the ***US*** took this path, not us!.
And I did mention the need to be sure what is on the card since all sorts of
subversion can be built in at this basic level.

So I think we are on the same side!

   Brian