Royal Holloway College academics have defended their research on controversial "key escrow" systems which could be used by government agencies to monitor private phone calls, faxes and email. They say the work is not secret, and that how it is used is a matter for open political debate.

The key escrow research was part of a three-year project in which the London college and the telecommunications companies Vodafone and GPT are studying security for the next generation of digital mobile telephones. The academic side of the project is funded by the Engineering and Physical Sciences Research Council. The industry side is 50 per cent funded by the Department of Trade and Industry.

According to Chris Mitchell, manager of the project's academic side, the key escrow work was undertaken on the project team's initiative and not to Government orders. In July the DTI paid for Holloway researcher Nigel Jefferies to travel to a conference in Brisbane and present a paper on key escrow. The paper is available on the Internet at ftp://ftp.isg.rhbnc.ac.uk/pub/3gs3.

"There needs to be a public debate about what kind of escrow system is appropriate and whether one is necessary," Professor Mitchell said.

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Henry Beker, visiting professor at Royal Holloway College and chief executive of the cryptographic company Zergo, called for an open discussion of key escrow. "My view is that technically we can solve the problems," he said. "It is a political issue, not a technical one."

The issue has arisen because future telephones are likely to be coded with the owner's personal "key", ensuring that conversations remain secret from anyone not possessing the key. Police and intelligence services could therefore lose their present ability to tap conversations.

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President Clinton's government proposed that duplicate keys should be held in escrow by the government and released to police and other agencies with legal authorisation. But critics argued that the scheme was open to abuse. The American system, which would require phone, fax and computer manufacturers to use the Skipjack algorithm and Clipper chip for encryption, remains stalled.

Peter Sommer, of the Computer Security Research Centre at the London School of Economics, believes that moves to introduce key escrow in the United Kingdom are unlikely to succeed. "People who want strong encryption do not have to go to the Government for it," he said, adding that encryption programs like PGP (Pretty Good Privacy) are readily available on the Internet. "Key escrow can only operate by consent in the end. The big financial players and international conglomerates can always move elsewhere."

Besides political objections, there are also technical problems with key escrow. Researchers at AT&T, IBM and Cambridge University have separately discovered three weaknesses in Clipper. Ross Anderson of Cambridge University now claims to have found a flaw in the scheme developed by Vodaphone and Royal Holloway College. He said he figured out how to break the scheme while hearing it described at the Brisbane conference.

Despite the Clipper setback, British government departments have maintained an interest in technologies which would allow them to intercept private digital communications. The THES understands that the secret service MI5 has been canvassing the opinions of business people and academics on the key escrow issue.

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