<%-- Page Title--%> Sci-Tech <%-- End Page Title--%>

<%-- Volume Number --%> Vol 1 Num 155 <%-- End Volume Number --%>

May 21, 2004

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Computer Chip Noise may Betray Code

The noise emitted by computer chips could help code breakers decipher encrypted messages, according to preliminary research carried out at the Weizmann Institute in Israel. Adi Shamir and Eran Tromer sampled the high-frequency audio produced by computer central processing units (CPU) - the highly complicated devices that perform the majority of calculations inside computers - in a recording studio.

They discovered that they could distinguish between different cryptographic keys being processed by the chip, according to the frequency of the sound emitted. They also found they could determine the length of a string of characters by measuring the duration of certain sounds. This is because these correspond to the amount of time taken to process the key. These details could, in theory, make it substantially simpler for an assailant to break the code used to protect valuable data on a computer

"Our preliminary analysis of acoustic emanations from personal computers shows them to be a surprisingly rich source of information on CPU activity," the researchers write on a web page outlining their work. "This looks like a very exciting finding," says Markus Kuhn, at Cambridge University in the UK. "It's another indication that there are many types of compromising emanations still waiting to be discovered." Kuhn notes that others have examined ways of monitoring the power-supply fluctuations exhibited by chips to remotely gather information about cryptographic activity.

Peter Honeyman at the University of Michigan is also impressed by the technique and says it seems especially promising because it is not disrupted by additional noise from a computer. The method detects only high-frequency CPU noise and filters out lower frequency sounds like the whirr of the fan inside a computer.

Obese people more likely to die in car crashes

Heavier people are more likely to be killed or seriously injured in car accidents than lighter people, according to new research. This could mean car designers would have to build in new safety features to compensate for the extra hazards facing overweight passengers. In the US, car manufacturers have already had to redesign air bags so they inflate to lower pressures, making them less of a danger to smaller women and children. But no one yet knows what it is that puts overweight passengers at extra risk.

A study carried out in Seattle, Washington, looked at more than 26,000 people who had been involved in car crashes, and found that heavier people were at far more risk. People weighing between 100 and 119 kilograms are almost two-and-a-half times as likely to die in a crash as people weighing less than 60 kilograms. And importantly, the same trend held up when the researchers looked at body mass index (BMI) - a measure that takes height as well as weight into account. Someone 1.8 metres tall weighing 126 kilograms would have a BMI of 39, but so would a person 1.5 metres tall weighing 88 kilograms. People are said to be obese if their BMI is 30 or over. The study found that people with a BMI of 35 to 39 are over twice as likely to die in a crash compared with people with BMIs of about 20. It is not just total weight, but obesity itself that's dangerous.

Crash tests normally use dummies that represent standard-sized males weighing about 78 kilograms. Recently, smaller crash-test dummies have also been used to represent children inside crashing cars. But larger and heavier dummies are not used, the US National Highway Traffic Safety Administration in Washington DC told New Scientist. The reasons for the higher injury and death rates are far from clear. Mock speculates that car interiors might not be suitably designed for heavy people. Or obese people, with health problems such as high blood pressure or diabetes, could be finding it tougher to recover from injury.

Richard Kent, an expert in impact biomechanics at the University of Virginia, thinks the new research has established a legitimate connection between obesity and severe injury or death. Because the research used BMI data, it has not confused taller (and therefore heavier than average) people with those who are overweight. People who are obese might also be at risk because seat belts do not hold them as securely in a crash. "For example, a large amount of [fat] tissue between the restraint system and the bony thorax acts much like a winter coat: it introduces "slack" into the restraint system and decreases its performance," Kent says.

Source: NewScientist.com





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