The speed at which you type may now be used to determine whether you are allowed to view your bank account details or use other online services.

A US company is aiming to reduce the risk of identity theft by introducing ‘bio-security’ to passwords, meaning that users would have to type their user name and password with consistent speed in order to be logged in.

The technology, which measures the time for which keys are held down, as well as the length between strokes, takes advantage of the fact that most computer users evolve a method of typing which is both consistent and idiosyncratic – especially for words used frequently such as a user name and password.

When registering, the user types his or her details nine times so that the software can generate a profile. Future login attempts are measured against the profile which, the company claims, can recognise the same user’s keystrokes with 99 per cent accuracy, using what is known as a “behavioural biometric.”

“In a climate of identity theft and the increasing need for data protection, there’s a need for a more portable and stronger way of authenticating individuals,” Jared Pfost, vice president of security of product strategy at BioPassword, said. "This is a cost-effective solution that doesn’t require any change in the user’s behaviour."

If users type with more vigour – or languor – than usual, additional security questions are posed to allow them to log in in the traditional manner.

When Times Online trialled the program, your correspondent’s unique typing style not only foiled the log-in attempts of two others, but could be replicated with no great concentration on his part. Similarly, he was unable to imitate other typists' strokes, no matter how closely he observed them.

BioPassword, which is based in Washington State, will compete with the key-ring sized devices that banks have taken to issuing which generate numbers at random for customers logging in to provide an additional layer of security.

Security experts were sceptical about the technology, however, saying that it had been around for some time, and that until its success was proven in large surveys, adoption would remain limited.

“What about if you’re trained as typist? Do you type the same way as others who learned the same way?” Paul Vlissidis, technical director at NCC Group, said. “Also, the system would need to be recalibrated every time you changed your password. With a fingerprint, that only happens once.”

Ross Anderson, a computing science expert at Cambridge University, dismissed the technology out of hand: “It’s been around for 20 years, and was tried and failed before. Typing patterns vary,” he said.

The idea of keystroke recognition has been around since the Second World War, when Morse code operators used it ascertain the identity of senders, but the technology was only formally developed in the 1980s.

Windows programs have for a long time captured keystroke information, Mr Pfost, himself a former Microsoft employee, said, but this was the first time it had been commercialised as a security solution.

Biopassword has more then 50 customers – mostly small banks and building societies – in the US, and recently announced it had secured $11 million (£5.5 million) in venture capital funding.

The system costs $34,000 (£17,000) to install, with a subscription of $1.15 (58p) per user per year.

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