US government attempts to extend its hegemony beyond its borders have reared their ugly heads again, this time with regard to an Israeli patent. Associated Press reports from Tel Aviv that an Israeli cryptologist claims to have developed a low-cost method of protecting computers, credit cards, passports and drivers’ licences from forgery, and is seeking a US patent on it. The system involves software programs combined with an embedded microprocessor Smart Card. Adi Shamir, 34, and two students, Amos Fiat and Uriel Feige, developed the system at the Weizmann Institute, Israel’s largest independent research centre, and last July, the institute applied for a US patent, saying the system had potential applications in a wide variety of commercial and milidary uses. In January, Shamir says, he received a remarkable and disconcerting letter from the US Commerce Department telling him he faced prosecution if he disclosed information about his findings. Shamir was to deliver a scientific paper on the project in May to a conference on theoretical computer science in New York City. After receiving the letter, he wrote to the programme committee about the order, which required the committee to retrieve and destroy all advance copies of his paper. Kenneth Cage, an attorney with the US Patent and Trademark Office in Washington, said he could not comment on the specifics of a pending patent application, adding that his office had the power to issue secrecy orders to US citizens if release of information in a proposed patent was deemed harmful to national security. Of 125,000 patent applications last year, about 6,000 were relayed to the Defense Department for review, and secrecy orders eventually were issued on about 150, Cage said. Shamir’s work is an outgrowth of a mathematical discovery called zero-knowledge proof, which allows one mathematician to convince another of a proposition’s truth without revealing details of the proof. In the case of credit cards, such a technique can be used to prove a credit card is valid without giving the number to someone who might misuse it. The same technique could be used to protect computer systems from invasion by hackers.