Do we need to subscribe to perform remote attestation?

[He__Yi]

Hi!

I read from the announcement on this board that subscription is needed to use the remote access (EPID) service. Am I understand it correctly?

After subscribing to DEV Intel® Software Guard Extensions Attestation Service (Linkable) using my account, I have successfully received a primary key and a secondary key and a SPID. Could you tell me how can I incorporate those two keys and SPID in remote attestation?

From SampleCode in sgx_sdk, remote attestation is like replacing local attestation's EREPORT MAC with a signature signed by the attestation key, which is obtained from Intel through the provisioning enclave. In sgx_sdk, EPID key provisioning service seems to be hidden in sgx_ra_get_msg1 function... Could you help me figure out how to incorporate this subscription into remote attestation?

Thank you so much!

[Scott_R_Intel · Accepted solution]

Hello.

Please refer to the more complete, full end-to-end remote attestation article and sample code at the links below.  This sample has been updated to use the subscription based APIs.

https://software.intel.com/en-us/articles/code-sample-intel-software-guard-extensions-remote-attestation-end-to-end-example

https://github.com/intel/sgx-ra-sample

Regards.

Scott

[He__Yi]

Hi, Scott!

Thank you for your reply!

Following three points are my understanding of the Attestation Service based on your reply. Could you help me take a look at them to see if they are correct?

[1] The Intel Attestation Service (IAS) is only needed on the server(Service Provider) side. The Service Provider ID I obtained from registration is used to (1) obtain the Signature Revocation List through GetSigRL and (2) verify a quote through VerifyQuote.

[2] The simplified RemoteAttestation example in SampleCode just uses a simulated service provider, which does not communicate with Intel, such that this example doesn't require a registration to IAS.

[3] IAS is not required on the Enclave's side (i.e. ISV side). On the Enclave side, EPID key provisioning is implemented by sgx_ra_get_msg1 function.

Thanks a lot!

[Scott_R_Intel]

Hello Yi.

You are correct in all 3 of your statements, but a couple of comments...

#2 - This is true, but just to be clear, because it doesn't truly talk to IAS, it can't truly verify the validity of an enclave/platform/TCB.

#3 - Just FYI, EPID provisioning is buried a little deeper than just that function, but yes, EPID provisioning is kicked off automatically if it hasn't happened yet.

Regards.

Scott

[He__Yi]

Perfect! Thank you so much!