Samizdata

Robert Matthews, a regular writer for QED column in the Sunday Telegraph, looks at the “wonders of technology” David Blunkett, the Home Secretary, decided it was time we should all benefit from.

Mr Blunkett appears to have fallen under the spell of biometric methods, which use characteristics ranging from fingerprints to handwriting to verify the identity of people. He seems to favour a particularly sophisticated version of the technology, which uses the unique iris patterns of the eye to check ID.

…there is still a stunning lack of awareness of a basic mathematical result that shows why we should all be very wary of any type of screening, biometric or otherwise.

In the case of screening – whether for breast cancer or membership of al-Qaeda – the [Bayes’s] theorem shows that the technology does not do what everyone from doctors to Home Secretaries seems to think it does.

To take a concrete example, suppose a biometric screening method is 99.9 per cent accurate: that is, it spots 99.9 per cent of imposters, and incorrectly accuses one in 1,000 bona fide people (in reality, these are very optimistic figures). Now suppose that every year a horde of 1,000 terrorists passes through Heathrow airport. What are the chances of the biometric system detecting any of them?

The obvious answer is 99.9 per cent. But, in fact, Bayes’s Theorem shows that the correct answer is about two per cent. That is, when the alarms go off and the armed response team turns up at passport control, it is 98 per cent likely to be a false alarm.

Why? Because not even the amazing accuracy of the biometric test can cope with the very low prior probability that any one of the 60 million passengers using Heathrow each year is a terrorist. Sure, it boosts the weight of evidence in favour of guilt 1,000-fold, but that is still not enough to overcome the initially very low probability of guilt.

So there you have it. You just need to calculate your probability of being one of the incorrectly accused one in 1,000 bona fide people and books your ticket accordingly.

The European Central Bank (ECB) is in talks with Hitachi Ltd. about embedding radio tags in euro bank notes to prevent counterfeiting of euros.

The ECB is deeply concerned about counterfeiting and money laundering and is said to be looking at radio tag technology. Last year, Greek authorities were confronted with of 2,411 counterfeiting cases and seized 4,776 counterfeit bank notes while authorities in Poland nabbed a gang suspected of making and putting over a million fake euros into circulation.

To add to the problem, businesses also find it hard to judge a note’s authenticity as current equipment cannot tell between bogus currency and old notes with worn-out security marks. Among the security features in current euros are threads visible under ultraviolet light.

According to Prianka Chopra, an analyst with market research firm Frost and Sullivan the main objective is to determine the authenticity of money and to
stop counterfeits.

RFID (Radio Frequency Identification) tags also have the ability of recording information such as details of the transactions the paper note has been involved in. It would, therefore, also prevent money-laundering, make it possible to track illegal transactions and even prevent kidnappers demanding unmarked bills.

Besides acting as a digital watermark, the use of radio chips could speed up routine bank processes such as counting. With such tags, a stack of notes can be passed through a reader with the sum added in a split-second, similar to how inventory is tracked in an RFID-based system.

Hitachi is developing noncontact chips for use in bank notes and other paper documents, Kantaro Tanii, confirmed the company’s corporate communications manager for Europe. Hitachi’s Web site describes a 0.4-mm by 0.4-mm by 60-micron radio frequency identification chip, called the Mu Chip, that works in the 2.45-GHz frequency band and has a 128-bit ROM for storing its identity number. It was originally conceived as a bank-note-tracking device but could also be used in passports, driver’s licenses and other official documents.