Subject: RE: The need for two grades of time data.

From: Mathew Butler <[email-masked]>
Date: Thu, 14 Sep 2000 15:52:38 -0700

Yes, there is.  Under the rules of the US Code of Federal Regulations,
"Unauthorized access to computer systems shall be a felony."  When you sign
an authentication challenge with a private key, you're attesting to the fact
that you're authorized to use the private key, and that if the signature is
accepted by the server, you are (to the best of your knowledge) utilizing
resources which you are authorized to access.

The same could be said of typing a password to a terminal -- "I am
authorized to use this password, and if you accept this password, I shall be
utilizing resources which I am authorized to access."

The problem is, with passwords the user can't truly take due diligence to
prevent the theft of their authentication credential.  With PK, they can.

-Mat Butler

-----Original Message-----
From: Stephen Kent [mailto:[email-masked]]
Sent: Thursday, September 14, 2000 11:22 AM
To: todd glassey
Cc: [email-masked]
Subject: Re: The need for two grades of time data.

<snip>

>Sure they do. Anything I sign with my Digital Cert is represented as my wet
>signature under the law . Making it essentially  a legal instrument of my
>agency. That's just the way it is.

No, it's not. I sign authentication challenges with a private key and 
there is no legal (NR) implication associated with that.

Steve

---

From: Stephen Kent <[email-masked]>
Date: Thu, 14 Sep 2000 19:36:17 -0400

Matt,

>resources which you are authorized to access.

First, I thought this applied only to federal computer systems, but I 
may be wrong. Second,  signing the authentication challenge is not a 
non-repudiable act. The security function is authentication, an input 
to an access control function. There is no presumption that I am 
aware of what is being signed, because it may be (in some protocols) 
random looking data that was generated under the control of the 
system that issued the challenge.  Worse yet, if this is typical, 
one-way authentication, I don't even know that the challenge was 
issued by the system in question.  So, from a technical perspective, 
I'm comfortable that this is not a legally binding digital signature, 
and that position is consistent with our document on technical 
aspects of NR.

>prevent the theft of their authentication credential.  With PK, they can.

In most respects, this is a quantitative difference, not a 
qualitative one. With SSL or SSH, we usually protect the password in 
transit, if we send it as a raw password. Yes, it's true that I never 
need to share a private key with the system to which I authenticate 
myself, but there are numerous password-based schemes that have the 
same property.  So long as we store private keys in software, which 
is common practice, there are many equivalent ways to steal my 
private key or my password from my PC.

The bottom line is that a real time user authentication process is 
characterized by many features that distinguish it from a NR 
signature process.

Steve