Re: [stir] Review of: draft-ietf-stir-passport-05

[Dave Crocker <[e-mail]>]

On 8/27/2016 5:19 PM, Eric Rescorla wrote:
>     And I believe that was my original guess, although my very limited
>     understanding of non-repudiation includes the significant burden of
>     having the timestamp, itself, be validated by an independent
>     authority. Otherwise, the signer could claim any time they want to...
>
>
> That doesn't seem correct to me, at least if "independent" means someone
> other than the relying party. The signature is itself a proof attaching
> the signer's private key to the passport and to a claim by the signer
> about the passport object's assertions being valid at the time in the
> timestamp. If the relying party checks the timestamp and rejects it if
> it has a bogus timestamp, then any acceptable passport will be
> relatively fresh and thus will be usable as a proof of the signer's
> representation at the relevant time. Overall, this seems less important
> than the freshness property wrt authentication, but it's still a
> technical property.


This sounds pretty much the same as authentication.

While the verifier might decide that the timestamp is ok, if the 
verification is close enough in time to that claimed occurrence, it does 
nothing for being able to prove the timing to a third-party, /later/. 
And that's the environment I'm used to hearing about needing 
'non-repudiation' for.

In that case, the timestamp needs to have validation that is independent 
of the signer.  What I'm used to hearing, for that, is that an 
independent timestamp service does a kind of notary signature on the 
original signer's stuff, including the timestamp.

Anyhow, all of seems to go beyond STIR's needs, suggesting that it would 
be best to remove use of the term?

d/

-- 

   Dave Crocker
   Brandenburg InternetWorking
   bbiw.net