The time when a person's written signature was taken as proof of their identity is long gone. Anyone who has opened a bank account recently knows that financial institutions demand a wide range of documentation before they are willing to process the application.

With fraud against consumers rising, most of us don't mind jumping through some hoops to prove who we are, even if it is a bit of a drag at times. Some people joke that it would be easier to have a bar code printed on the back of your neck so companies could just scan you in and find out who you are. Many government agencies and businesses agree - except they are not joking.

There's no need for a bar code, though, as the human body itself provides more than one unique characteristic. Fingerprinting has been with us for quite some time, but biometric technology now allows for fingers, faces, irises and even smells to be scanned and stored in vast databases.

The government plans to make this new technology a part of our lives. It says biometric identification will help stamp out terrorism and all manner of fraud and that innocent people have nothing to fear. Let's look at some of the benefits, and the potential risks.

Biometric technology relies on the fact that many features of our bodies are unique and can easily be recorded by computers and matched with other records, such as name, address and date of birth. You've probably heard about how biometrics could be used to replace the ream of passwords and personal identification numbers (Pins) that many people struggle to remember.

However, it is the fear of terrorist attacks and soaring fraud that is driving the use of biometrics forward at a pace few are comfortable with, as governments place the highest priority on knowing who is visiting their country.

A chip off the old block
The government now wants to establish a biometric feature as the cornerstone of passport applications, and hopes this will lead to the development of a national identification card.

Your photograph will be scanned and saved as a computer file on a microchip embedded in your passport. A standard agreed by the International Civil Aviation Organisation insists there must be enough room on that chip to store other data, such as iris and fingerprint scans.

The UK has already begun testing biometric technology for both security and commercial purposes. A company called EyeTicket has already carried out a six-month trial of its JetStream iris-scanning software at Heathrow airport, which it says was successful. Participating passengers passing through UK immigration were invited to look into a camera, intended to identify them within one or two seconds.

According to Stewart Mann, chairman of EyeTicket: "There were no security breaches during six months of continuous operation, and carefully monitored tests showed a zero error rate in identification."

Heathrow, British Airways and Virgin Atlantic were reportedly impressed with the results and the Home Office has pledged to introduce iris scanning at more UK sites in order to identify regular visitors.

Bringing a tear to the eye
However, an MP who volunteered to take part in the trial of ID card iris-scanning technology (not supplied by EyeTicket) wasn't quite as impressed. Just trying to use the eye scanner brought tears to the eyes of Bob Russell, MP, making it impossible for the equipment to take a reading. The people in charge of the trial admitted that watery eyes and even long eyelashes could cause problems. The failure rate was seven per cent of those tested.

Fingerprint scanners aren't without problems either, as Barclaycard discovered when it tried the technology. It found that people with rough hands, such as manual workers, or those who had recently used hand cream could not be scanned.

Privacy campaigners have argued that facial recognition systems can be fooled just as easily as customs officials, with disguises, beards, prosthetics or even plastic surgery. Simon Davies, director of Privacy International, says: "Facial recognition is completely discredited." According to technology analysis company Gartner, the software may not work well with certain types of camera, while lighting and the position of the face could also cause inaccuracies.

But banks and credit card providers remain excited by biometrics. Last year, Lloyds TSB tested a system that verifies identity by matching the sound of a user's voice, which the bank hopes will provide a cheap and easy way to safeguard telephone and internet banking services. The Nationwide Building Society is still trying out a system that records and measures the distinctive pressure and rhythm of a traditional signature.

Who am I?
The problem is that biometrics doesn't necessarily prove who you are - it simply proves who you are not. If somebody managed to attach your name and details to their own biometric scans, then they would effectively become you. This sort of ID theft could be difficult to disprove, largely because the government is presenting biometrics as 'foolproof'.

That may sound a bit far-fetched, but with a scheme that hopes to uniquely identify and record a nation of 60 million people, the devil is going to be in the details. The important thing to remember about security technology is that it only minimises risk. If you have two locks and an alarm protecting your house the opportunist thief will be deterred but a determined burglar will not be put off so easily.

The same applies to technology. In theory, it's possible to break any form of encryption, including the codes that are used to protect our credit card details online. But it takes weeks and a stack of supercomputers, and most thieves simply don't have the time or skill to make it worth their while.

That's why ID thieves turn to more mundane means, such as tricking people into revealing information or rooting through bins for paperwork, as the recent phishing scams have shown us.

Knowing me, knowing you
So the key to biometrics is making sure that those who present the initial biometric data are in fact who they say they are. If the new biometric passports use facial recognition, as expected, it will actually be easier and cheaper to use existing methods of identification - sending in an authenticated photograph and/or a birth certificate. However, there remains a black market for all kinds of counterfeit documents and the government's plans for authenticating people and their documents are undeniably in the early stages.

The thought of the data - whether it's the proof of identity used while registering biometrics or the actual scans - falling into the wrong hands is frightening. Privacy International has warned that the value of 'owning' someone else's identity will promote corruption among the agencies that collect and process the data. Such information could attract a very high price.

Biometric scanning is going to become a reality for all of us but many questions remain unanswered. Technology has a part to play in helping us protect our identities but predictions that it will safeguard our identities beyond any doubt should be taken with a large pinch of salt.

ID to go
Biometric data could guarantee free healthcare for members of the European Union if they are taken ill while travelling on the continent. All Britons travelling in Europe next year will be issued with a credit card-sized ID, but by 2008 the cards will contain a chip, with each EU country at liberty to choose whether to include photographs, fingerprints or iris scans along with health records. Conservative MPs such as John Redwood have already levelled accusations against the government of getting "an ID card in by the back door".

Safer PCs
Digitalpersona introduced a fingerprint scanner for laptops and handheld computers last summer. Called the U-are-U Personal, it allows users to protect their data with a fingerprint scan. A little later in the year, PC maker Gateway announced that it was introducing the technology on its computers.

Panasonic also introduced its PC-compatible Iris Identification Camera last year, which records an identification photo of the iris and compares it with an iris pattern stored on a database, reportedly within two seconds.