Subject: Server-signatures: Re: proposed key usaged text -- the final round

From: "Anders Rundgren" <[email-masked]>
Date: Sun, 28 Nov 1999 09:08:32 -0000

Hi Guys,
I just wonder how your NR-text matches server-based signatures.
The following text of yours indicates some problems in this area:

    >The protection afforded private keys is a critical factor in main-
    >taining security. On a small scale, failure of users to protect
    >their private keys will permit an attacker to masquerade as them, or
    >decrypt their personal information. [stuff about CA keys deleted]

"entity owning the private keys" used in other places looks like a
good replacement for user.   Or why not start with a definition of
user that can be both a person or a device and that
a person can be the owner or just be a trusted user (employee) of said private keys?

Anders

---

From: Tony Bartoletti <[email-masked]>
Date: Tue, 30 Nov 1999 18:21:16 -0800

>a person can be the owner or just be a trusted user (employee) of said private keys?

Anders,

Let me explore the latter application.  Suppose I am a "company-trusted"
employee, using a company-owned "private key".  I assume further that the
company has its own mechanism for (hoping to) control who has the use of
a given key at a given time, or at least who is responsible for its use.

Now, I use the private key in question, entering into some obligation with
an external RP.  Later, I attempt to deny my actions, causing this RP some
hardship.

My understanding is that this "bindings" in question look like:

   RP <---> Transaction <---> Key/Cert <---> Company <---> Me

That is, the RP must take up issue with the company, being the owner
(or certSubject or Operator) of the key, directly.  It falls upon the
company to follow the chain, so to speak, and take me to task.

The central point is that the RP has only a certificate, and its
"named holder", to point to in a dispute.  If the means by which
the company above "secures the connection between key and user"
is hidden from view, no amount of NR-servicing on the RP side can
suffice to hold the "user" accountable.  They are forced instead to
pressure the company, who may in turn pressure the employee.

Perhaps I don't fully understand all of the details you assume to
hold in the server-based example.  I may be confusing different
scenarios:

1.  Cert says "owned by BigCorp, as key nnn" but I control its use,
    or at least I did last Thursday when I checked it out.

2.  Cert says "owned by Tony", and the company controls its use in
    some automated system, with my supposed blessings/restrictions.

In the second case, the RP would be expected to come after me directly.
If I am innocent, I am forced to take issue with the company.

In each case, the RP can turn only to the "certificateSubject".

Could you elaborate?

___tony___ 

Tony Bartoletti                                             LL
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Lawrence Livermore National Laboratory                LL LL LL
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