Messages in this thread | | | Date | Tue, 14 Feb 2017 08:38:29 -0600 | From | "Dr. Greg Wettstein" <> | Subject | Re: [tpmdd-devel] [RFC] tpm2-space: add handling for global session exhaustion |
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On Fri, Feb 10, 2017 at 04:13:05PM -0500, Kenneth Goldman wrote:
Good morning to everyone.
> James Bottomley <James.Bottomley@HansenPartnership.com> wrote on > 02/10/2017 11:46:03 AM: > > > > quote: 810 milliseconds > > > verify signature: 635 milliseconds
For those who may be interested in this sort of thing I grabbed a few minutes and ran these basic verification primitives against a Kaby Lake system.
Average time for a quote is 600 milliseconds with a signature verification clocking in at 100 milliseconds. The latter is consistent with what James found on his Skylake machine.
Latencies are still significant with things like container start times.
> > Part of the way of reducing the latency is not to use the TPM for > > things that don't require secrecy:
> Agreed. There are a few times one would verify a signature inside the > TPM, > but they're far from mainstream: > > 1 - Early in the boot cycle, when there's no crypto library. > > 2 - When the crypto library doesn't support the required algorithm. > > 3 - When a ticket is needed to prove to the TPM later that it verified > the signature.
I don't think there is any doubt that running cryptographic primitives in userspace is going to be faster then going to hardware. Obviously that also means there is no need for a TPM resource manager which has been the subject of much discussion here.
The CoreOS paper makes significant reference to increased security guarantees inherent in the use of a TPM. Obviously whatever uses those are will have the noted latency constraints.
We have extended our behavior measurement verifications to the container level so we offer an explicit guarantee that a container has not operated in a manner which is inconsistent with the intent of its designer. Getting the security guarantee we need requires that an linkage to a hardware root of trust hence our concerns about hardware latency.
Have a good day.
As always, Dr. G.W. Wettstein, Ph.D. Enjellic Systems Development, LLC. 4206 N. 19th Ave. Specializing in information infra-structure Fargo, ND 58102 development. PH: 701-281-1686 FAX: 701-281-3949 EMAIL: greg@enjellic.com ------------------------------------------------------------------------------ "UNIX is simple and coherent, but it takes a genious (or at any rate, a programmer) to understand and appreciate its simplicity." -- Dennis Ritchie USENIX '87
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