70 Science and technology 2 stered when it emerged that the Justice De-
partment was demanding Apple’s help in at least nine similar cases (in seven of those, the firm is resisting). Some fret that the FBI might even require the firm to start sending subverted code to specific suspects over the air, using the technology it employs to distribute legitimate updates. Viewed narrowly, that might be no bad thing. The FBI has argued many times that encryption can thwart legitimate investigations, leaving vital clues undiscovered. But security researchers point out that what works for the good guys works for the bad guys, too. If a subverted operating system managed to escape into the “wild” even once, then the security of every iPhone would be put at risk. The trade-off, says Kenneth White, a director of the Open Crypto Audit Project, an American charity, is not security versus privacy, but security for everyone versus the police’s ability to investigate specific crimes. And the risk of a leak would rise with every extra person who had access to the nobbled code: defence lawyers demanding to see it; courtappointed experts given the job of checking it works as intended; and so on. A second argument against collaboration points out that Apple has governments besides America’s that it must answer to. Deliberately compromising its security for the Americans, says Dr White, will encourage other countries to make similar, perhaps even broader, demands for access. Having conceded the point once, Apple will find it hard to resist in future. In countries less concerned with civil liberties and the rule of law, that could have serious consequences. Key decisions All these arguments are set to be rehearsed when Apple and the FBI meet in court, on March 22nd. But however the decision goes, it is unlikely to be the last word. Most observers expect appeals to carry on all the way to the Supreme Court. In the meantime IT firms, Apple included, are taking steps to lock themselves out of their own customers’ devices, deliberately making it harder to fulfil official requests for access. New versions of the iPhone feature something called the Secure Enclave. This is a separate computer within the phone, whose job is to police access to the rest of the device. Cracking it would require an extra piece of customised software aimed at neutering the Enclave itself. That is doable, for Apple has retained the ability to alter the Enclave so that it can issue updates and fix bugs. But things need not stay this way. The firm has pondered removing its ability to modify the Enclave, which would frustrate official requests for access. Even then, a determined policeman has options. It is possible, with expensive equipment and a good deal of skill, to recover cryptographic keys from hardware
The Economist February 27th 2016 by poking around physically in the transistors and wiring of the chip itself. Decapping, as this process is known (the first step is to remove the chip’s protective plastic cap) is the stuff of intelligence agencies and a few dedicated laboratories, and carries a risk of destroying the chip for no gain. But, if access were thought crucial, and there were no other options, it is possible to do it. Even so, ensuring that phones themselves can be unlocked will not solve all of the authorities’ problems. There are plenty of encrypted messaging apps available for smartphones, many written outside the United States and thus beyond the reach of its government. The most advanced feature a technique called forward secrecy, which uses disposable, one-time encryption keys to ensure that old messages stay scrambled even if those looking manage to get hold of the conversers’ permanent keys. (One such app, called Telegram, which was developed by Pavel Durov, a nomadic Russian, announced on February 24th that it had reached 100m users.) All this may sound like an arms race. It
is. Silicon Valley has roots in the counterculture of the 1960s, and a potent streak of civil libertarianism. There is a sense there that Mr Snowden’s revelations proved the American government cannot be trusted not to abuse its powers of surveillance. And there are commercial factors, too. Apple has made privacy and security important selling points for its products. Cybersecurity types, meanwhile, feel aggrieved that policemen and politicians do not seem to grasp what they view as a fundamental point: weakening security for the police’s benefit inevitably weakens it for everyone. “They keep asking for a ‘Manhattan Project’ to figure this out,” says Dr White. “But that’s like asking for a Manhattan Project to figure out how to divide by zero.” (Attempting to dividing by zero is, by definition, a mathematical folly.) It will be left to the courts to decide the right approach in this particular case. But the fight between Apple and the FBI raises very big questions. To answer them will ultimately require the intervention of elected politicians. 7
Cancer
A run a day keeps the tumour at bay
Exercise protects against cancer. Researchers now understand why
A
MPLE evidence shows that exercising regularly reduces the risk of cancer. Similarly, those who have survived the disease are less likely to see it return if they engage in lots of physical activity after treatment. All this suggests that such activity triggers a reaction in the body which somehow thwarts cancer cells, but the details of the process have remained murky. Now, a team led by Pernille Hojman at Copenhagen University Hospital, in Denmark, has reported in Cell Metabolism that the key to the mystery is adrenalin. Dr Hojman began her work by verifying that exercise truly does have beneficial anti-tumour effects. She and her colleagues gave some of the mice in their laboratory activity wheels, which the animals could run around inside as much as they liked. Other mice, meanwhile, were given no opportunity to exercise beyond moving about inside their cages. The researchers then induced
mice of both sorts to develop one of three types of cancer. Some, they injected with a substance called diethylnitrosamine, which causes liver cancer. Others, they injected below the skin with melanoma cells, which then set up shop where they had been injected. Others still had their tails inoculated with melanoma cells. In mice, previous experience has shown, this leads to melanomas forming in the lungs. The results were instructive. While all mice injected under the skin with melanoma cells developed that cancer, the tumours in animals which had had access to a running wheel were 61% smaller after six weeks than were those in mice that had been unable to exercise. A similar reduction in size (58%) pertained to lung tumours. And, of the mice injected with diethylnitrosamine, only 31% of those with wheels in their enclosures developed tumours at all—in contrast to a 75% tumour-develop- 1