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Boffins use heartbeat to thwart wireless implant hack

Chinese cardiac crypto

Interfering with wireless medical implants sounds like a movie threat plot rather than a real risk - but if there is a threat, Chinese boffins have come up with an ingenious solution for combating it.

Researchers from the Chinese University of Hong Kong have developed a technique for using a patient's heartbeat as the source for an encryption key for authenticating communications between medical technicians and implanted devices such as insulin pumps and pacemakers, Heise Security reports.

Two sensors would be involved: one in an implanted device and one in a control kit. A pulse taken from a patient's finger is put into the control device. The interval between 16 successive heartbeats is then used to derive a 64-bit code. With the implanted device and the control kit keying off the same source, an identical key would be produced.

Minor differences in the measurement of heart rates taken from different locations in the body can be accommodated. Proto-type test systems have a 6.5 per cent code pair rejection rate, comparable with the 4.2 per cent rejection rate derived from fingerprint systems. Unlike conventional biometric systems, minor variations in heart rate intervals mean that potential attackers would not be able to use recorded data to derive a key.

Chinese medical boffins are yet to try out the technology with real implants. Instead they used test systems where they recorded heart rate data taken off sensors on the right and left index fingers of subjects. Two types of sensors were used: an electrocardiogram, which measures electrical pulses, and a photoplethysmograph (PPG), which works out a heart rate from variation in light absorption under the skin.

The research was presented in a paper published by the IEEE's Transactions on Information Technology in Biomedicine journal. ®

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