Subject: Re: Authentication or integrity?

From: Darren Moffat <[email-masked]>
Date: Wed, 4 Apr 2001 15:06:48 -0700 (PDT)

>On Wed, 4 Apr 2001, Darren Moffat wrote:
>
>> Everything you said about integrity makes sense.  However my view of
>> what SACRED intends to provide is to address the case where I need to
>> prove to some remote machine that I am who I claim to be so that it
>> can decided to give me the credentials that are mine.
>
>And I'm claiming that proving my identity to a remote machine is
>not necessary.  All I have to do is prove to myself the "are mine"
>part.

So how then do you protect against an offline attack on the cred bundles ?
 
>> Taking your locker analogy.  The locker has a simple key, but inside
>> it have stored my car keys, house keys, my bank cards and cheque book.
>> What I want from SACRED is a mechanism that allows me to authenticate
>> to the locker and then once doing that download the contents (the locker
>> itself should not interpret the contents).
>
>So what's the mechanism that prevents an eavesdropper from interpreting
>the contents during the download?  I.e. the confidentiality part.

I don't believe that has yet be specified in SACRED (or if it has I've
missed it), but I was assuming it would be there.

>Now it looks like things would be more secure if you had to unlock
>the locker and also unlock its contents, but wouldn't that mean that you
>have to remember (or carry around) two keys?

Am I correct in saying that in your case the locker is open but the
contents are locked ?
 
>> When downloading the contents of the locker we should use a transport
>> mechanism that ensures the intgrity over space, I think the integrity
>> over time issue is outside the scope of what SACRED can provide since
>> to SACRED the contents of the creds are opaque.
>
>Even though it's opaque, you still need to know that the opaque bit blob
>is bit for bit identical to what is was then (over time).

Are you suggesting I carry around a message hash to verifiy this or some
other means ?

--
Darren J Moffat