Encyclopedia of Computer Science and Technology

copy protection 117out to the volunteers. When a given unit has been analyzedby the program on the user’s machine, the results are sentback to the central server and a new work unit is sent.Although no evidence of extraterrestrial intelligencehad been found as of mid-2008, SETI@Home’s more than 5million participants have contributed more than 2 millionyears of CPU time, and can process at the collective rate of256 TeraFLOPS (trillion floating point operations per second),comparable with the fastest single supercomputers.There are currently a number of other cooperative distributedcomputing projects underway. Many of them arepart of the Berkeley Open Infrastructure for Network Computing(BOINC), which includes SETI@Home, Proteins@home (protein folding), and the World Community Grid(humanitarian projects).Ad hoc cooperative processing is not suitable for alltypes of projects. There must be a way to break the datainto batches that can be separately processed. The projectis also dependent on the number of volunteers and theirdegree of commitment.Cooperative processing can be seen as part of a spectrumof emerging ways in which the line between producersand consumers of data is being blurred. Other examplesinclude media-sharing services such as Gnutella (see filesharingand p2p networks). Cooperative programs canalso be used to gather information about software use andbugs from thousands of users to allow for faster debuggingand optimization.People can do more than passively share their computer’sprocessors—they can add their own brains tothe effort. Some of the most effective spam filters (seespam) use the “collective intelligence” of users by havingthem identify and mark spam messages, which can thenbe used by the software as a template for automaticallyrejecting similar messages. Another interesting applicationby the Carnegie Mellon Human Computation programuses a computer game where a pair of randomlyselected volunteers assigns keywords to an image. Forthe players, the object of the game is to come up withmatching keywords, thereby scoring points. However, thereal work that is being accomplished is that thousands ofpreviously uncategorized images are receiving appropriatekeywords to enable them to be retrieved. In effect,the system is taking advantage of an image-recognitiondevice that is far more capable than any computer algorithm—thehuman brain! (One might call this synergistichuman–computer processing.)Further ReadingBerkeley Open Infrastructure for Network Computing. Availableonline. URL: http://boinc.berkeley.edu/. Accessed September4, 2007.DeHon, Andre, et al. “Global Cooperative Computing.” Availableonline. URL: http://www.ai.mit.edu/projects/iiip/colab/gcc-abstract.html. Accessed September 4, 2007.Gomes, Lee. “Computer Scientists Pull a Tom Sawyer.” WallStreet Journal (June 27, 2007): p. B1. Available online. URL:http://online.wsj.com/article/SB118288538741648871.html.Accessed September 4, 2007.SETI@Home. Available online. URL: http://setiathome.berkeley.edu/. Accessed September 4, 2007.Shankland, Stephen. “Cooperative Computing Finds Top PrimeNumber.” ZDNet. Available online. URL: http://news.zdnet.com/2100-9584_22-5112827.html. Accessed September 4,2007.Taylor, Ian J. From P2P to Web Services and Grids: Peers in a Client/Server World. New York: Springer, 2004.copy protectionCompanies that produce software have had to cope withsoftware that is expensive to develop, while the disks onwhich it is distributed are inexpensive to reproduce. Themaking and swapping of “pirated” copies of software isjust about as old as the personal computer itself. Softwarepiracy has taken a number of forms, ranging from teenagedhackers making extra copies of games to factories (often inAsia) that stamp out thousands of bogus copies of Windowsoperating systems and programs that would cost hundredsof dollars apiece if legitimate (see software piracy andcounterfeiting).To prevent such copying, software producers in the1980s often recorded the programs on floppy disks in a specialformat that made them hard to copy successfully. Oneway to do this is to record key information on disk tracksthat are not normally read by the operating system and thusnot reproduced by an ordinary copy command. When sucha program runs, it can use a special device control routineto read the “hidden” track. If it does not find the identifyinginformation there, it knows the disk is not a legitimate copy.Another way to do copy protection is by having theprogram look for a small hardware device called a “dongle”connected to the computer, usually to the parallel printerport. Since the dongle is distributed only with the legitimateprogram, it can serve as an effective form of copyprotection. (Encryption can also be used to render copiesunusable without the key.)Decline of Copy ProtectionCopy protection has a number of drawbacks. Because diskbasedcopy protection writes on nonstandard tracks, evenlegitimate programs may not work with certain models ofdisk or CD drive. And because the legitimate user is unableto make a backup copy of the disk, if it is damaged, the userwill be unable to use the program. Dongles, on the otherhand, can interfere with the operation of other devices connectedto the port, and a user might be required to use multipledongles for multiple programs.During the 1990s, copy protection was generally phasedout, except for some games. A variety of other strategies areused against software piracy. The Software Publishers Association(SPA) maintains a program in which disgruntledusers can report unauthorized copying of software at theirworkplace. Companies that allow unauthorized copying ofsoftware can be sued for violating the terms of their softwarelicense. International trade negotiations can includeprovisions for cracking down on the massive “cloning” ofmajor software packages abroad.With modern software, “soft” copy protection generallystill exists in the form of requiring the typing in of aserial number from the CD, often combined with online