On Thu, 2020-02-13 at 15:11 -0500, Ken Goldman wrote:

On 2/11/2020 11:10 AM, david.safford@gmail.com wrote:

quoted

There is no reason to resend the same data for every attestation,
nor is there any reason to store already attested measurements anywhere
on the client. By versioning the log file names, userspace gets a
simple way to know what has and has not been attested, and for small
embedded devices we don't need to waste memory or filesystem space
on the data already attested.

Yes ... no.

There isn't any reason to resend measurements that a verifier has 
already received.  In fact, the logic I coded also said "if PCR 10 
didn't change, there's no need to even ask for the measurement log".

However, don't you have to save already attested measurements for
the case where there are multiple verifiers?  A different verifier would 
have to receive all measurements.

Certainly for the use case of multiple verifiers, the client would not 
delete the data until all verifiers had acknowledged receipt.

My main point was that there are at least some use cases in which the
client does not need to keep the measurement list, and IMA should 
support the option of exporting and deleting the list in these cases.

dave