Encyclopedia of Computer Science and Technology

78 central processing unitcentral processing unit See CPU.Cerf, Vinton D.(1943– )AmericanComputer ScientistVinton (Vint) Cerf is a key pioneer in the development ofthe packet-switched networking technology that is the basisfor the Internet. In high school, Cerf distinguished himselffrom his classmates by wearing a jacket and a tie and carryinga large brown briefcase, which he later described as“maybe a nerd’s way of being different.” He has a lifelonglove for fantasy and science fiction, both of which exploredifference. Finally, Cerf was set apart by being hearingimpairedas a result of a birth defect. He would overcomethis handicap through a combination of hearing aids andcommunications strategies. And while he was fascinated bychemistry and rocketry, it would be communications, math,and computer science that would form his lifelong interest.After graduating from Stanford in 1965 with a B.S. inmathematics, Cerf worked at IBM as an engineer on itstime-sharing systems, while broadening his background incomputer science. At UCLA he earned on M.S. and then aPh.D. in computer science while working on technologythat could link one computer to another. Soon he was workingwith Len Kleinrock’s Network Measurement Center toplan the ARPA network, a government-sponsored computerlink. In designing software to simulate a network that asyet existed only on paper, Cerf and his colleagues had toexplore the issues of network load, response time, queuing,and routing, which would prove fundamental for the realworldnetworks to come.By the summer of 1968, four universities and researchsites (UCLA, UC Santa Barbara, the University of Utah, andSRI) as well as the firm BBN (Bolt Beranek and Newman)were trying to develop a network. At the time, a customcombination of hardware and software had to be devisedto connect each center’s computer to the other. The hardware,a refrigerator-sized interface called an IMP, was stillin development.By 1970, the tiny four-node network was in operation,cobbled together with software that allowed a user on onemachine to log in to another. This was a far cry from asystem that would allow any computer to seamlessly communicatewith another, however. What was needed on thesoftware end was a universal, consistent language—a protocol—thatany computer could use to communicate withany other computer on the network.In a remarkable display of cooperation, Cerf and hiscolleagues in the Network Working Group set out to designsuch a system. The fundamental idea of the protocol is thatdata to be transmitted would be turned into a stream of“packets.” Each packet would have addressing informationthat would enable it to be routed across the network andthen reassembled back into proper sequence at the destination.Just as the Post Office doesn’t need to know what’sin a letter to deliver it, the network doesn’t need to knowwhether the data it is handling is e-mail, a news article, orsomething else entirely. The message could be assembledand handed over to a program that would know what to dowith it.With the development of what eventually became TCP/IP (Transmission Control Protocol/Internet Protocol) VintCerf and Bob Kahn essentially became the fathers of theInternet we know today (see tcp/ip). As the online worldbegan to grow in the 1980s, Cerf worked with MCI in thedevelopment of its electronic mail system, and then set upsystems to coordinate Internet researchers.In later years, Cerf undertook new initiatives in thedevelopment of the Internet. He was a key founder and thefirst president of the Internet Society in 1992, serving in thatpost until 1995 and then as chairman of the board, 1998–1999. This group seeks to plan for expansion and changeas the Internet becomes a worldwide phenomenon. Cerf’sinterest in science fiction came full circle in 1998 when hejoined an effort at the Jet Propulsion Laboratory (JPL) inPasadena, California. There they are designing an “interplanetaryInternet” that would allow a full network connectionbetween robot space probes, astronauts, and eventualcolonists on Mars and elsewhere in the solar system.In 2005 Cerf joined Google as its “chief Internet evangelist,”where he has the opportunity to apply his imaginationto network applications and access policies. Cerf alsoserved as chairman of the board of the Internet Corporationfor Assigned Names and Numbers (ICANN), a position thathe left in 2007.Cerf has received numerous honors, including the IEEEKobayashi Award (1992), International TelecommunicationsUnion Silver Medal (1995), and the National Medal of Technology(1997). In 2005 Cerf (along with Robert Kahn) wasawarded the Presidential Medal of Freedom, the nation’shighest civilian award.Further Reading“Cerf’s Up.” Personal Perspectives. Available online. URL: http://global.mci.com/ca/resources/cerfs_up/personal_perspective/.Accessed May 28, 2007.Hafner, Katie and Matthew Lyon. Where Wizards Stay Up Late: theOrigins of the Internet. New York: Simon & Schuster, 1996.Henderson, Harry. Pioneers of the Internet. San Diego, Calif.:Lucent Books, 2002.certificate, digitalThe ability to use public key encryption over the Internetmakes it possible to send sensitive information (suchas credit card numbers) to a Web site without electroniceavesdroppers being able to decode it and use it for criminalpurposes (see encryption and computer crime andsecurity). Any user can send information by using a personor organization’s public key, and only the owner of thepublic key will be able to decode that information.However, the user still needs assurance that a site actuallybelongs to the company that it says it does, ratherthan being an imposter. This assurance can be providedby a trusted third party certification authority (CA), suchas VeriSign, Inc. The CA verifies the identity of the appli-