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. 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 .
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 .
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,
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.
Cheers, Ed Gerck
 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.
 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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