UK government's biometric plans undermined
The biometric technique that has been selected for incorporation into the
new UK national ID card has been undermined in the scientific press. New
Scientist has reported that the technique of iris scanning is not as
perfect and infallible as the Home Secretary (Minister of Internal
Affairs) has claimed. The article alleged that the technology was prone to
failure and that its success could not be guaranteed if used on a national
New Scientist reported that the key problem “is the limited accuracy of
biometric systems combined with the sheer number of people to be
identified. The most optimistic claims for iris recognition systems are
around 99 per cent accuracy – so for every 100 scans, there will be at
least one false match”.
“This is acceptable for relatively small databases, but the one being
proposed will have some 60 million records. This will mean that each
person’s scan will match 600,000 records in the database, making it
impossible to stop someone claiming multiple identities. Even if they
already had one or more records in the database, these would be swamped by
the hundreds of thousands of false matches”.
The magazine quoted Simon Davies, director of EDRI member Privacy
International, as saying that the technology’s performance would not
improve in the foreseeable future.
The Guardian took Davies critique to a more complex level. “A system with
0.999999 reliability would make a false match, on average, once every
million times – great for verification. But for identification, the
chances of the system correctly comparing someone with its entire database
can be calculated by its success rate to the power of the database size.
If that is two, with the example above it would be 0.999999 squared, or
0.999998. That means 100 people would produce a 0.9999 success rate,
100,000 a 0.9048 success rate. A database holding the whole UK population
– 50 million – leads to less than one in five thousand billion billion –
in other words, useless”.
Media extensively reported the issue, first through Reuters and then in
the International Herald Tribune. The allegations sparked a lengthy and
heated email exchange between Davies, iris scanning inventor John Daugman,
and many of the world’s leading biometric experts. New Scientist will
publish some of the exchanges this week.
‘Biometric cards will not stop identity fraud’, New Scientist (21.11.2003)
‘Report faults biometric ID card plans’, Reuters (20.11.2003)
‘Image Problem’, The Guardian (20.11.2003)