> On May 19, 2016, at 10:59 PM, Dave Tian <dave.jing.t...@gmail.com> wrote:
> 
> 
> 
>> On May 19, 2016, at 8:06 PM, Keith Packard <kei...@keithp.com> wrote:
>> 
>> Oliver Neukum <oneu...@suse.com> writes:
>> 
>>> I think we would need to use a form of public key cryptography
>>> in the same manner used to verify authorship of emails. The host
>>> would provide a nonce value that the device encrypts and returns.
>>> The host would verify the signature.
>> 
>> We could initially provision the devices with a unique key and provide
>> the public half on a piece of paper. You'd have to get that into the
>> kernel before the system needed any entropy though, and that seems hard.
>> 
>> -- 
>> -keith
> 
> Note that when we are talking about a nonce from host and a signature from 
> the device, we may potentially refer to TPM attestation.
> The TPM has its own unique private key embedded in the hardware to derive 
> other keys, such as the attestation keys,
> which can be used by the remote to verify the target’s firmware.
> I am personally in favor of a TPM-like solution, since we probably 
> couldn’t/shouldn’t disable the firmware update anyway,
> and we really need a hardware root of trust (with a key embedded) in the 
> device, like the TPM in the host.
> 
> Whether this key should be provisioned by the user or the manufacture is 
> another interesting story.
> Intel’s SGX[1] remote attestation is based on Intel’s EPID[2], which means if 
> the user want to make sure
> the desire enclave code is running on an Intel SGX-enabled CPU, he/she has to 
> ask Intel for help,
> since only Intel is able to verify if the attestation result was from a legit 
> CPU with SGX enabled.
> Apparently, it does not sound good. So people did not like the patch[3].
> So Intel is going to add a user-defined root-of-trust key in the CPU, which 
> can be set during the boot time[4].
> Now the solution seems more decent, since now we do not have to deal with 
> Intel anyway.
> BUT this does not mean Intel cannot do anything evil or users have a more 
> secure solution for CPU-based attestation.
> 
> Credit card A let users to pick up a password - however, users have to be 
> responsible for identity thefts.
> Credit card B does not have password at all - instead, users can dispute each 
> transaction.
> Which one would you use?
> 
> -daveti
> 
> 
> [1]https://software.intel.com/en-us/sgx
> [2]https://en.wikipedia.org/wiki/Enhanced_privacy_ID
> [3]http://www.spinics.net/lists/linux-driver-devel/msg83272.html

resend~

-daveti

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