government interest in more conventional forms of cryptography, catapulting cryptography to the position of best understood and most satisfactory part of information security.

Today, public-key cryptography has given birth to a second generation of systems, replacing the modular arithmetic of the first generation with arithmetic on elliptic curves. The U.S. Data Encryption Standard of the 1970s, an algorithm of moderate strength, has been replaced with the Advanced Encryption Standard, which may be the most secure and carefully studied algorithm in the world. Technical developments have been accompanied by a change of heart at the

National Security Agency, which has embraced the public developments by adopting a “Suite B” of public algorithms as satisfactory for all levels of classified traffic. Cryptography is now the soundest aspect of information security, and modern security systems are rarely penetrated by confronting the cryptography directly.

Computer security has not fared as well. Progress developing high-assurance systems, though substantial, has not been as great as expected or required. Implementation of features in most commercial computing has taken precedence over security, and the state of Internet security is widely lamented. Real progress awaits major improvements in both construction and evaluation of computer programs.

In contrast to cryptography’s solid technical status and the fact that the Secure Sockets Layer is the most widely deployed cryptographic mechanism of all time, SSL effectiveness is limited. The weak computer-secu-rity foundation on which cryptography must be implemented has made it problematic to scale the key management system to Internet size.

Coupled with this is a serious human-factors failure of all security systems. The Internet is a medium in which users want to talk to both people and machines they trust, as well as to those they don’t trust. Unfortunately, the means to recognize those who are trustworthy (and, say, accept upgrades to programs from them) is not available. As a result, cryptography has failed to protect us from a network in which a quarter of the computers have been captured by bot networks and half the email is spam.

What will happen over the next half century? Two great challenges loom:

True computer, communications, and network security are seen by police and intelligence agencies as an obstacle to the prevention of terrorism. Although attempts to block the use of good cryptography sub-

sided at the end of the 1990s, a program of building-in ubiquitous wiretapping is being carried out at a pace that does not inspire confidence that the interception facilities will be secure against capture and misused by parties unknown.

More fundamental is the growth of Web services. Today, even the most security-conscious companies cannot avoid trusting their engineering and marketing directions to Google and its trade-secret techniques. The query stream reveals all of our interests, and only Google’s good practices and reputation guarantee they are not put at the service of competitors. Much sooner than the next half century, Web services

BRITISH CRYPTOLOGISTS USED AN ELECTROMECHANICAL DEVICE CALLED THE BOMBE, DESIGNED BY ALAN TURING AND REBUILT HERE FOR THE BLETCHLEY PARK MUSEUM, TO HELP BREAK CODE SIGNALS FROM THE GERMAN ENIGMA MACHINE DURING WORLD WAR II.

will have destroyed locality in computing.

No significant corporate computation will take place on any one organization’s machines. Programs will look at various yellow pages and advertisements and choose the most cost-effective providers for their most intensive computations. Image rendering, heat flow, marketing campaign modeling, and a host of services not yet imagined will be provided by myriad companies offering proprietary solutions.

When this happens, what we call secure computation today—you did it on your own computer and protected it adequately—may be gone forever. ^c

WHITFIELD DIFFIE ( [e-mail]) is the chief security officer, a vice president, and a Sun Fellow of Sun Microsystems, Mountain, View, CA.