Re: [EAT] Introduction

[Carl Wallace <[e-mail]>]

This gets at one difference between current attestation formats. Some
require the generator to save the attestation if needed later, others are on
demand.

From:  EAT <[e-mail]> on behalf of Shawn Willden
<swillden=[e-mail]>
Date:  Friday, September 7, 2018 at 7:45 AM
To:  "Smith, Ned" <[e-mail]>
Cc:  "[e-mail]" <[e-mail]>
Subject:  Re: [EAT] Introduction

> Proof of protection is a good description of what Keystore attestation aims to
> accomplish, and timeliness or "freshness" is important.  Keystore achieves the
> latter with a challenge value supplied by the verifier.
> 
> On Thu, Sep 6, 2018 at 6:21 PM Smith, Ned <[e-mail]> wrote:
>> |--- snip ---
>> 
>> |So Keystore provides a valuable tool to authors of apps that require strong
>> |security. For example, for a key used to authenticate an account holder to
>> |a banking system. But this tool is much less valuable if the bank's server
>> |can't verify that the secret is managed in a trusted environment. Hence,
>> |Keystore attestation, which allows the trusted environment to prove that it
>> |secures the key material, and specifies the authorizations that define how
>> |it may be used.
>> 
>> --- snip ---
>> Right, the main objective of attestation is to provide evidence to a verifier
>> regarding the trustworthiness properties of the environment that protects
>> keys and other important things. It goes beyond traditional
>> proof-of-possession.. I think of it as proof-of-protection (PoPr) though that
>> term isn’t widely used. Distinguishing between storage and use may be
>> important since protection techniques differ for each. At the end-of-the-day,
>> attestation expects there is a ‘verifier’ – some entity that wants to check
>> attestation evidence – who engages with the ‘attester’ following some sort of
>> protocol to pass attestation evidence. Timeliness of evidence exchange can be
>> important since, often, environments that protect key storage and use will
>> change during deployment (after initial manufacturing). Attestation protocol
>> is needed to facilitate a timely exchange of attestation evidence. I think
>> these aspects are a primary area where IETF could add value to attestation
>> infrastructure.
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> -- 
> Shawn Willden | Staff Software Engineer | [e-mail] | 801-477-4296
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