identification + Re: authentication and authorization

[Anton Stiglic]

-----Original Message-----
From: owner-cryptography at metzdowd.com
[mailto:owner-cryptography at metzdowd.com] On Behalf Of Ed Gerck
Sent: 7 juillet 2004 14:46
To: cryptography at metzdowd.com
Subject: identification + Re: authentication and authorization

>I believe that a significant part of the problems discussed here is that
>the three concepts named in the subject line are not well-defined. This
>is not a question of semantics, it's a question of logical conditions
>that are at present overlapping and inconsistent.
>
>For example, much of what is called "identity theft" is actually
>"authentication theft" -- the stolen credentials (SSN, driver's
>license number, address, etc) are used to falsely *authenticate* a
>fraudster (much like a stolen password), not to identify. 

Yes and no.  The problem is that most authentication and authorisation
schemes today are actually identification and authentication and
authorisation schemes.  Even when you read CISSP study guides, they always
describe it in 3 steps, identification, authentication and authorisation.
The thing is that we can do without identification.  Identification is not
necessary, even if you want accountability.  In
Identification-authentication-authorisation schemes, identification is the
process of pin-pointing an exact individual from a set of individuals (e.g.
SSN allows you to define a unique united-states citizen), authentication is
the process of verifying that the individual claiming to be who he
identified himself as, is really that individual.   But most systems don't
really need identification, all they need is a proof that the individual
possesses a certain attribute.  It is possible to do authentication and
authorisation, without doing the identification part!   For example, it is
possible to prove that you are a united-states citizen that has a valid SSN
number, without actually giving out information about SSN.

Why is identity theft a bad thing?  Usually, you don't want your identity to
be stolen because you could be accused of something due to accountability
that is associated with your identity.  The problem is not that someone can
authenticate himself to a system he is not suppose to have access to, the
problem is that a thief can identify himself as you and authenticate himself
as you, and than do bad things (like transfer your money).

The problem is not really authentication theft, its identity theft, or if
you want to put it even more precisely, it's "identity theft and
authenticating as the individual to whom the identity belongs to".  But the
latte doesn't make for a good buz-word :)

Here is another way of seeing it.  Consider a system where you need to
authenticate yourself as a citizen, of some region, that is 18 years of age
or older, in order to participate in some gambling thing say.  One way to
implement the authentication and authorisation in the system is to have each
individual identify themselves, and then authenticate themselves.  If the
individual is part of a set of individuals that are known to be over 18,
then the individual is given access.  Another way to implement it is to have
each individual prove that they are over 18 without identifying themselves,
using Stefan Brands digital credentials say.  If the authentication is
successful, the un-identified individual is given access.  In the latter
case, you don't really care about authentication theft unless there is some
sort of accountability (with Stefan's digital credentials, you can embed the
identity in the tokens that are presented for authentication, the identity
can only be revealed under certain circumstances, for example excessive use
or if require by a law, it could be revealed by a third party).

I do agree that stronger authentication does help, preferably authentication
based on zero-knowledge protocols, since these reveal less information about
the individual's identity that can be used to impersonate the individual.

--Anton





Once we
understand this, a solution, thus, to what is called  "identity theft"
is to improve the *authentication mechanisms*, for example by using
two-factor authentication. Which has nothing to do with identification,
impersonation, or even the security of identification data.

In further clarifying the issue, it seems that what we need first is
a non-circular definition for identity. And, of course, we need a
definition that can be applied on the Internet.  Another important
goal is to permit a safe automatic processing of identification,
authentication and authorization [1].

Let me share with you my conclusion on this, in revisiting the
concept of identification some time ago. I found it useful to ask
the meta question -- what is identification, that we can identify it?
In short, a useful definition of identification should also work
reflexively and self-consistently [2].

In this context, what is "to identify"? I think that "to identify"
is to look for connections. Thus, in identification we should look
for logical and/or natural connections. For example:

- between a fingerprint and the person that has it,

- between a name and the person that answers by that name,

- between an Internet host and a URL that connects to it,

- between an idea and the way we can represent it in words,

- conversely, between words and the ideas they represent,

- etc.

Do you, the reader, agree?

If you agree you have just identified. If you do not agree, likewise
you have identified! The essence of identification is thus to find
connections -- where absence of connections also counts.

Identification can thus be understood not only in the sense of an
"identity" connection, but in the wider sense of "any" connection.
Which one to use is just a matter of protocol expression, need, cost
and (very importantly) privacy concerns.

The word "coherence" is useful here, meaning any natural or logical
connection. To identify is to look for coherence. Coherence with and
between a photo, a SSN, an email address, a public-key and other
attributes: *Identification is a measure of coherence*.

The same ideas can be applied to define "authentication" and
"authorization" in a self-consistent way, without overlapping with
each other.

Comments?

Cheers,
Ed Gerck

[1] The effort should also aim to safely automate the process of reliance
by a relying-party. This requires path processing and any algorithm to
eliminate any violations of those policies (i.e., vulnerabilities) that
might be hard to recognize or difficult to foresee, which would
interfere with the goal of specifying a wholly automated process of
handling identification, authentication and authorization.

[2] This answer should be useful to the engineering development of all
Internet protocols, to all human communication modes, to all
information transfer models and anywhere one needs to reach beyond
one's own point in space and time.

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