From Tsinghua University to Cambridge, and from the Stanford Research Institute (SRI) to becoming a distinguished engineer at Sun Microsystems, an engineer from Beijing has become one of the world's great experts in the arcane area of cryptographic protocols, the science behind computer security. What he is called, however, has been the source of a certain amount of confusion. His name is Gong Li. The Chinese characters for Gong Li, the goddess actress of the silver screen, are different from the ones for Gong Li, the engineer. The tones of 'Gong' are also different, and so most Chinese do not see or hear the similarity that is deceiving in the romanisation. For Mr Gong, however, this is little more than an amusing diversion. 'I used to get a lot of love-letter e-mails addressed to Ms Gong, but it seems to have dropped off recently,' he said. In a quiet, unassuming way, Mr Gong has always been something of a rebel. In the early 1980s, he applied to university in Beijing when the government was a lot stricter than today. 'Back then, when you sat the national entrance exam in China, you could list 10 universities you would like to go to. At the bottom of the list, there was a little check box that asked: 'If you do not get into your university of choice, will you allow the government to select one for you?' 'Everybody checked this box because it was thought that if you did not, you might be considered some kind of trouble maker. I only put down Tsinghua and I did not check the box. My friends told me it could be dangerous.' Not only did he get into Tsinghua, China's most prestigious science and engineering university, he sailed through, getting his degrees in record time. His professors had some problems getting research funding for his computer science department until one listened to a military friend who said: 'There's lots of money in data security, you know.' That launched the professor and his students into the dark, strange, mathematical world of computer security. Just as he was finishing his degree, Britain was negotiating with China for the handover of Hong Kong. One result of that was that shipping magnate Sir Y.K. Pao created a scholarship for Chinese students to study in Britain. Mr Gong was one of the first accepted - at both Cambridge and Oxford. But because the Oxford acceptance letter arrived two weeks after the one from Cambridge, he ended up at Jesus College, Cambridge, where he worked with computer legends, David Wheeler and Roger Needham. His Cambridge experience was chastening. 'When I arrived in England, I could read and write English, but my spoken ability was limited. The system was also completely different from what I had known in China. It is a beautiful town but it can be a very difficult place. 'They throw you into the middle of the lake and watch you swim back to shore, if you can.' Mr Wheeler was the adviser for Mr Gong's PhD thesis and although he was there to guide, he made few direct decisions, preferring to keep his charges on their toes. 'I kept asking him when I could begin writing, but he would never say anything directly. I had to work out everything for myself,' Mr Gong said indicating it forced him to think for himself, which was of course the whole purpose. The Cambridge experience has put him in a different orbit from many other Chinese students who studied abroad. 'Most Chinese think that the United States is the best at everything. Those of us who have had the good fortune to study in Europe see things quite differently. We learn that there are many ways to look at the world and we often look at each other knowingly when we are in America. We have a shared background that those who went only to America do not have,' he said. Mr Gong performed well, at one point solving a problem that most computer scientists had thought was unsolvable. It was a problem that dealt with the use of simple passwords in a networked environment. Hackers have simple tools that can break easy passwords - the ones most people use because they are easy to remember, such as a simple name or word in English. Truly difficult passwords are so difficult to remember that they are not used by most people. Mr Gong worked out a way for people to use simple passwords but for the computer to keep them safe from prying eyes. 'One day I was walking through Jesus Common and the idea came to me. I then took a while to examine it and discovered that it really could work,' he said. He was asked by several US laboratories to work for them. Unfortunately, he did not have a green card - necessary to work for any lab that did government-level research. He eventually found a job on the east coast, stayed there long enough to get the right papers and then went straight to the SRI, one of America's most prestigious computer science labs. He was there at the beginning of what has become a phenomenal movement in the way computers are programmed. At Sun Microsystems, the leading maker of Unix servers that run most of the backbone of the Internet, an engineer had created a new programming language. It was called Java. The engineer, James Gosling, insisted it would be a 'secure' platform on which to write software. The word 'secure' set off Mr Gong and his colleagues at SRI. 'We decided to hold a workshop and invited [Mr] Gosling and a lot of other specialists from Netscape, Microsoft and other computer companies to attend.' At the end of the workshop, Mr Gong told the Sun engineer he was going about security issues in the wrong way. '[Mr] Gosling admitted to me that they needed help, and so they hired me to do all the security for the Java platform.' Java is built on top of elements known as 'classes', modules that perform certain duties but do not interfere with each other. That is the theory, at least. If you have ever experienced a computer freeze, when the only thing you can do is turn it off and then back on again, you have probably experienced some kind of interference. This kind of interference can also allow hackers to get inside, so protecting 'classes' from each other is an important part of good security. When Mr Gong wrote his first book on Java Security (Inside Java 2 Platform Security, Addison-Wesley, 1999), he quoted Mao Zedong: 'Never forget class struggle'. It was a gentle jest that many of the Berkeley-educated Sun engineers found quite amusing. Mr Gong is managing director of the Sun China Engineering & Research Institute in Beijing. Sometimes he daydreams about how he played basketball for Tsinghua, or bridge for Cambridge. And occasionally, he will still get another misguided love-struck reminder that he is not the only talented Chinese named Gong Li.