The Secret Function
Ryan Singel at Secondary Screening points to this General Accounting Office document (pdf) about Homeland Security's work on the airline passenger screening system.
According to the statement from the Transportation Security Administration, the original proposal known as CAPPS-II has these capabilities:
- Watch list matching
Comparison of data contained in the passenger's reservation (PNR=Passenger Name Record) with information contained in government watch lists (selectee and no-fly lists) to identify potential threats to aviation security and other individuals of interest to the counterterrorism community
[Comment: The common objective is the watch list is the logic and basis are Sensitive Security Information that cannot be disclosed, but some of the observed results were obviously wrong (e.g. Senator Edward Kennedy was on the watch list) and it is a nightmare to get off the list]
- CAPPS I rules application
Matching information in the PNR to CAPPS I rules to identify individuals who should be subject to additional security screening (e.g. expert system rules that flag people for paying buying one-way tickets with cash, etc.)
[Comment: On one hand, this may bring in the 'dumb' terrorists but not the smart one, who know how to set up a good profile. On the other hand, this is prejudicial to those without credit cards (such as poor students). In any case, this usually just take a few more minutes of the individuals' time.]
- Identity authentication
Checking PNR data against commercial databases to assist in confirming the passenger's identity
[Comment: The commercial databases don't always have the information (e.g. if you just moved recently, they won't have your latest address) and they are not always correct (see previous post: Matching Names for Data Mining).]
- Criminal checks
Matching PNR data against lists of international fugitives and government "wanted lists" to identify known criminals
[Comment: This is legal, but it is not done in other realms of life.]
- Intelligence-based search for unknown terrorists
Using algorithms developed through intelligence modeling to identify previously unknown terrorists by searching for patterns in an individual's travel or transaction history that are indicative of terrorist activities
[Comment: I am skeptical about the performance characteristics of such algorithms (namely, false positive and false negative incidences), but such results are Sensitive Security Information.]
- Use of opt-in lists
Maintaining a list of individuals, who have been previously cleared under credentialing programs, such as registering passengers in advance of making reservations, to minimize the volume of passengers that must be prescreened
[Comment: If I travel often enough, I would opt in.]
- Use of alert lists
Providing the capability to create a temporary watch list based on information extracted from current intelligence reports, such as blocks of stolen passports
[Comment: It is about time that they maintain a list of stolen passport numbers. But a current intelligence report could also mean "four Chinese persons carrying a nuclear bomb are heading towards Boston, according to an anonymous phone call in Tijuana from a person with a Spanish accent."]
But then there is a mysterious footnote: "TSA planned to incorporate eight capabilities into the CAPPS II program. We have only listed seven of these capabilities, because one is Sensitive Security Information."
What is that eighth capability? Ryan Singel issues this challenge: "Name that secret function. Prizes will be awarded in various categories, including a handmade tinfoil cap for the best conspiracy theory and an authentic, fully redacted FOIA response page from the TSA for the most ludicrous suggestion."
It would seem that the seven capabilities are broad enough that they encompass everything possible about the individual (Is the PNR valid? Is the person on any "wanted list", a known terrorist, or otherwise fall in an all-purpose "current intelligence"?) as well as a black box known as an "expert rules system/intelligent predictive model?). These capabibilities are broad and general enough that all actions are permissible under one or another reason. So why should there be a top-secret eighth capability?
I would guess that the eighth capability has to do with reverse migration of information. If information had been flowing from various government agencies and private commercials (such as commercial database suppliers and airlines) to the TSA for the purpose of making decisions at the airport, the consolidated information may flow back to those agencies and companies in the name of enhancing homeland security. For example, if the FBI was interested in a specific individual in a new investigation, they would have the entire air travel history on file without requiring any warrants; and so on. But this is a guess.