[cryptography] Your GPU's ???Fingerprint??? Could Lead to New Security Methods

Jonas Wielicki development at sotecware.net
Tue Oct 30 14:13:37 EDT 2012

On 30.10.2012 14:30, Natanael wrote:
> Yeah, this looks like TPM with software protection instead of hardware
> protection.
> Rootkits can screw it up.

I guess that is why the researchers suggested an on-GPU
challenge-response protocol implementation which would not hand out the
initial SRAM state directly to any software.

> Den 30 okt 2012 14:27 skrev "Solar Designer" <solar at openwall.com>:
>> This is very curious, but ...
>> On Tue, Oct 30, 2012 at 10:08:06AM +0100, Eugen Leitl wrote:
>>> Cloning the actual SRAM state in a GPU is not possible, said Dr. Lange.
>> "What
>>> we've done so far in our research is reading out this SRAM state. We can
>> of
>>> course copy this readout. What we're aiming for is to put an
>> authentication
>>> system in place where the GPU never hands over the raw data. Instead the
>> GPU
>>> uses it in a challenge-response protocol, just like the secret key in a
>>> signature system or zero-knowledge protocol. This does rely on the OS
>> and/or
>>> hypervisor shielding the card from bad requests, such as ???hand over
>> all your
>>> secrets,???" she said.
>> ... since it relies on OS and/or hypervisor security anyway, about the
>> same functionality and security (not a lot of it) can be achieved by
>> keeping the secret in a disk file (protected with filesystem/OS
>> permissions) and having the crypto implemented in an OS driver (or
>> privileged program).  Use of a GPU does not appear to provide much
>> advantage on top of that.  It can't be physically cloned, but if OS
>> security fails, then the GPU's secrets can be cloned and the
>> authentication protocol simulated in host software (on attacker's
>> machine, without the GPU).
>> Alexander
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