File-Sharing Programs: Peer-to-Peer Networks Provide Ready Access to Child Pornography
Published: 2003-02-20T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: The availability of child pornography has dramatically increased in recent years as it has migrated from printed material to the World Wide Web, becoming accessible through Web sites, chat rooms, newsgroups, and now the increasingly popular peer-to-peer file-sharing programs. These programs enable direct communication between users, allowing users to access each other's files and share digital music, images, and video. GAO was requested to determine the ease of access to child pornography on peer-to-peer networks; the risk of inadvertent exposure of juvenile users of peer-to-peer networks to pornography, including child pornography; and the extent of federal law enforcement resources available for combating child pornography on peer-to-peer networks. Because child pornography cannot be accessed legally other than by law enforcement agencies, GAO worked with the Customs Cyber-Smuggling Center in performing searches: Customs downloaded and analyzed image files, and GAO performed analyses based on keywords and file names only. In commenting on a draft of this report, the Department of Justice agreed with the report's findings and provided additional information.
section_title: What GAO Found
paragraphs: Child pornography is easily found and downloaded from peer-to-peer networks. In one search using 12 keywords known to be associated with child pornography on the Internet, GAO identified 1,286 titles and file names, determining that 543 (about 42 percent) were associated with child pornography images. Of the remaining, 34 percent were classified as adult pornography and 24 percent as nonpornographic. In another search using three keywords, a Customs analyst downloaded 341 images, of which 149 (about 44 percent) contained child pornography. These results are in accord with increased reports of child pornography on peer-to-peer networks; since it began tracking these in 2001, the National Center for Missing and Exploited Children has seen a fourfold increase--from 156 in 2001 to 757 in 2002. Although the numbers are as yet small by comparison to those for other sources (26,759 reports of child pornography on Web sites in 2002), the increase is significant. Juvenile users of peer-to-peer networks are at significant risk of inadvertent exposure to pornography, including child pornography. Searches on innocuous keywords likely to be used by juveniles (such as names of cartoon characters or celebrities) produced a high proportion of pornographic images: in our searches, the retrieved images included adult pornography (34 percent), cartoon pornography (14 percent), child erotica (7 percent), and child pornography (1 percent). While federal law enforcement agencies--including the FBI, Justice's Child Exploitation and Obscenity Section, and Customs--are devoting resources to combating child exploitation and child pornography in general, these agencies do not track the resources dedicated to specific technologies used to access and download child pornography on the Internet. Therefore, GAO was unable to quantify the resources devoted to investigating cases on peer-to-peer networks. According to law enforcement officials, however, as tips concerning child pornography on peer-to-peer networks escalate, law enforcement resources are increasingly being focused on this area.

section_title: Letter
paragraphs: The availability of child pornography has dramatically increased in recent  years as it has migrated from magazines, photographs, and videos to the  World Wide Web. The Internet’s wide range of information search and  retrieval technologies, which make it possible to quickly find a vast array  of information, also make it easy to access, disseminate, and trade  pornographic images and videos, including child pornography.  Increasingly, child pornography is accessible through Web sites, chat  rooms, newsgroups, and the increasingly popular peer-to-peer technology,  which allows direct communication between computer users, so that they  can access and share each other’s files (including images, video, and  software).
As requested, our objectives were to determine (1) the ease of access to  child pornography on peer-to-peer networks; (2) the risk of inadvertent  exposure of juvenile users of peer-to-peer networks to pornography,  including child pornography; and (3) the extent of federal law enforcement  resources available for combating child pornography on peer-to-peer  networks.
To address the first two objectives, we were assisted by the U.S. Customs  CyberSmuggling Center in using a peer-to-peer application to search for  image files matching keywords that were intended to identify pornography  and child pornography images or that might accidentally identify  pornographic images. The resulting files were downloaded, saved,  analyzed, and classified by a U.S. Customs CyberSmuggling agent. To  determine what federal law enforcement resources are allocated to  combating child pornography on peer-to-peer networks, we analyzed  resource allocation data at the Federal Bureau of Investigation and the  Child Exploitation and Obscenity Section within the Department of  Justice, and at the U.S. Customs Service and U.S. Secret Service within the  Department of the Treasury. We also received documentation about what  resources were being allocated to combat child pornography from the  National Center for Missing and Exploited Children, a federally funded  nonprofit organization that serves as a national resource center for  information related to crimes against children.
Appendix I contains a more detailed discussion of our objectives, scope,  and methodology. Appendix II provides more information on the  characteristics and use of peer-to-peer file-sharing programs.
subsections: section_title: Background
paragraphs: Federal statutes provide for civil and criminal penalties for the production,  advertising, possession, receipt, distribution, and sale of child  pornography. Of particular relevance to this report, the child pornography  statutes prohibit the use of any means of interstate or foreign commerce  (which will typically include the use of an interactive computer service) to  sell, advertise, distribute, receive, or possess child pornography.
Additionally, federal obscenity statutes prohibit the use of any means of  interstate or foreign commerce or an interactive computer service to  import, transport, or distribute obscene material or to transfer obscene  material to persons under the age of 16.
Child pornography is defined by statute as the visual depiction of a  minor—a person under 18 years of age—engaged in sexually explicit  conduct. By contrast, for material to be defined as obscene depends on  whether an average person, applying contemporary community standards,  would interpret the work—including images—to appeal to the prurient  interest and to be patently offensive, and whether a reasonable person  would find the material lacks serious literary, artistic, political, or  scientific value.
In addition to making it a crime to transport, receive, sell, distribute,  advertise, or possess child pornography in interstate or foreign commerce,  federal child pornography statutes prohibit, among other things, the use of  a minor in producing pornography, and they provide for criminal and civil  forfeiture of real and personal property used in making child pornography  and of the profits of child pornography. Child pornography, which is  intrinsically related to the sexual abuse of children, is unprotected by the  First Amendment. Nor does the First Amendment protect the production,  distribution, or transfer of obscene material.
In enacting the Child Pornography Prevention Act of 1996, Congress  sought to expand the federal prohibition against child pornography from  images that involve actual children to sexually explicit images that only  appear to depict minors but were produced without using any real  children. The act defines child pornography as “any visual depiction,  including any photograph, film, video, picture, or computer or computer- generated image or picture” that “is, or appears to be, of a minor engaging  in sexually explicit conduct” or is “advertised, promoted, presented,  described, or distributed in such a manner that conveys the impression  that the material is or contains a visual depiction of a minor engaging in  sexually explicit conduct.” Last year, the Supreme Court struck down this  legislative attempt to ban “virtual” child pornography in Ashcroft v. The  Free Speech Coalition, ruling that the expansion of the act to material that  did not involve and thus harm actual children in its creation is an  unconstitutional violation of free speech rights. According to government  officials, this ruling may increase the difficulty faced by law enforcement  agencies in prosecuting those who produce and possess child  pornography. Since the government must establish that the digital images  of children engaged in sexual acts are those of real children, it may be  difficult to prosecute cases in which the defendants claim that the images  in question are of “virtual” children.
subsections: section_title: The Internet Has Emerged as the Principal Tool for Exchanging Child Pornography
paragraphs: Historically, pornography, including child pornography, tended to be  found mainly in photographs, magazines, and videos. The arrival and the  rapid expansion of the Internet and its technologies, the increased  availability of broadband Internet services, advances in digital imaging  technologies, and the availability of powerful digital graphic programs  have brought about major changes in both the volume and the nature of  available child pornography. The proliferation of child pornography on the  Internet is prompting wide concern. According to a recent survey, over 90  percent of Americans say they are concerned about child pornography on  the Internet, and 50 percent of Americans cite child pornography as the  single most heinous crime that takes place on line.
According to experts, pornographers have traditionally exploited—and  sometimes pioneered—emerging communication technologies—from the  dial-in bulletin board systems of the 1970s to the World Wide Web—to  access, trade, and distribute pornography, including child pornography.  Today, child pornography is available through virtually every Internet  technology (see table 1).
Among the principal channels for the distribution of child pornography are  commercial Web sites, Usenet newsgroups, and peer-to-peer networks.
Web sites. According to recent estimates, there are about 400,000  commercial pornography Web sites worldwide, with some of the sites  selling pornographic images of children. The profitability and the  worldwide reach of the child pornography trade was recently  demonstrated by an international child pornography ring that included a  Texas-based firm providing credit card billing and password access  services for one Russian and two Indonesian child pornography Web sites.
According to the U.S. Postal Inspection Service, the ring grossed as much  as $1.4 million in just 1 month selling child pornography to paying  customers.
Usenet. Usenet newsgroups are also providing access to pornography,  with several of the image-oriented newsgroups being focused on child  erotica and child pornography. These newsgroups are frequently used by  commercial pornographers who post “free” images to advertise adult and  child pornography available for a fee from their Web sites. The increase in  the availability of child pornography in Usenet newsgroups represents a  change from the mid-1990’s, when a 1995–96 study of 9,800 randomly  selected images taken from 32 Usenet newsgroups found that only a small  fraction of posted images contained child pornography themes.
Peer-to-peer networks. Although peer-to-peer file-sharing programs are  largely known for the extensive sharing of copyrighted digital music, they  are emerging as a conduit for the sharing of child pornography images and  videos. A recent study by congressional staff found that one use of file- sharing programs is to exchange pornographic materials, such as adult  videos. The study found that a single search for the term “porn” using a  similar file-sharing program yielded over 25,000 files, more than 10,000 of  which were video files appearing to contain pornographic images. In  another study, focused on the availability of pornographic video files on  peer-to-peer sharing networks, a sample of 507 pornographic video files  retrieved with a file-sharing program included about 3.7 percent child  pornography videos.
section_title: Several Agencies Have Law Enforcement Responsibilities Regarding Child Pornography on Peer-to-Peer Networks
paragraphs: Table 2 shows the key national organizations and agencies that are  currently involved in efforts to combat child pornography on peer-to-peer  networks.
The National Center for Missing and Exploited Children (NCMEC), a  federally funded nonprofit organization, serves as a national resource  center for information related to crimes against children. Its mission is to  find missing children and prevent child victimization. The center’s  Exploited Child Unit operates the CyberTipline, which receives child  pornography tips provided by the public; its CyberTipline II also receives  tips from Internet service providers. The Exploited Child Unit investigates  and processes tips to determine if the images in question constitute a  violation of child pornography laws. The CyberTipline provides  investigative leads to the Federal Bureau of Investigation (FBI), U.S.  Customs, the Postal Inspection Service, and state and local law  enforcement agencies. The FBI and the U.S. Customs also investigate  leads from Internet service providers via the Exploited Child Unit’s  CyberTipline II. The FBI, Customs Service, Postal Inspection Service, and  Secret Service have staff assigned directly to NCMEC as analysts.
Two organizations in the Department of Justice have responsibilities  regarding child pornography: the FBI and the Justice Criminal Division’s  Child Exploitation and Obscenity Section (CEOS).
The FBI investigates various crimes against children, including federal  child pornography crimes involving interstate or foreign commerce. It  deals with violations of child pornography laws related to the production  of child pornography; selling or buying children for use in child  pornography; and the transportation, shipment, or distribution of child  pornography by any means, including by computer.
CEOS prosecutes child sex offenses and trafficking in women and children  for sexual exploitation. Its mission includes prosecution of individuals  who possess, manufacture, produce, or distribute child pornography; use  the Internet to lure children to engage in prohibited sexual conduct; or  traffic in women and children interstate or internationally to engage in  sexually explicit conduct.
Two organizations in the Department of the Treasury have responsibilities  regarding child pornography: the Customs Service and the Secret Service.
The Customs Service targets illegal importation and trafficking in child  pornography and is the country’s front line of defense in combating child  pornography distributed through various channels, including the Internet.  Customs is involved in cases with international links, focusing on  pornography that enters the United States from foreign countries. The  Customs CyberSmuggling Center has the lead in the investigation of  international and domestic criminal activities conducted on or facilitated  by the Internet, including the sharing and distribution of child  pornography on peer-to-peer networks. Customs maintains a reporting  link with NCMEC, and it acts on tips received via the CyberTipline from  callers reporting instances of child pornography on Web sites, Usenet  newsgroups, chat rooms, or the computers of users of peer-to-peer  networks. The center also investigates leads from Internet service  providers via the Exploited Child Unit’s CyberTipline II.
The U.S. Secret Service does not investigate child pornography cases on  peer-to-peer networks; however, it does provide forensic and technical  support to NCMEC, as well as to state and local agencies involved in cases  of missing and exploited children.
In November 2002, we reported that federal agencies are effectively  coordinating their efforts to combat child pornography, and we  recommended that the Attorney General designate the Postal Inspection  Service and Secret Service as agencies that should receive reports and tips  of child pornography under the Protection of Children from Sexual  Predators Act of 1998 in addition to the FBI and Customs.
The Department of Justice, while agreeing with our finding that federal  agencies have mechanisms in place to coordinate their efforts, did not  fully support our conclusion and recommendation that federal  coordination efforts would be further enhanced if the Postal Inspection  Service and the Secret Service were provided direct access to tips  reported to NCMEC by remote computing service and electronic  communication service providers. Justice said that the FBI and Customs,  the agencies that currently have direct access, can and do share these tips  with the Secret Service and the Postal Inspection Service, as appropriate,  and Justice believes that this coordination has been effective. Justice  questioned whether coordination would be further enhanced by having the  Secret Service and the Postal Inspection Service designated to receive  access to these tips directly from NCMEC; however, Justice said that it is  studying this issue as it finalizes regulations implementing the statute.
section_title: Peer-to-Peer Applications Provide Easy Access to Child Pornography
paragraphs: Child pornography is easily shared and accessed through peer-to-peer file- sharing programs. Our analysis of 1,286 titles and file names identified  through KaZaA searches on 12 keywords showed that 543 (about 42  percent) of the images had titles and file names associated with child  pornography images. Of the remaining files, 34 percent were classified as  adult pornography, and 24 percent as nonpornographic (see fig. 1). No  files were downloaded for this analysis.
The ease of access to child pornography files was further documented by  retrieval and analysis of image files, performed on our behalf by the  Customs CyberSmuggling Center. Using 3 of the 12 keywords that we used  to document the availability of child pornography files, a CyberSmuggling  Center analyst used KaZaA to search, identify, and download 305 files,  including files containing multiple images and duplicates. The analyst was  able to download 341 images from the 305 files identified through the  KaZaA search.
The CyberSmuggling Center analysis of the 341 downloaded images  showed that 149 (about 44 percent) of the downloaded images contained  child pornography (see fig. 2). The center classified the remaining images  as child erotica (13 percent), adult pornography (29 percent), or  nonpornographic (14 percent).
These results are consistent with the observations of NCMEC, which has  stated that peer-to-peer technology is increasingly popular for the  dissemination of child pornography. However, it is not the most prominent  source for child pornography. As shown in table 3, since 1998, most of the  child pornography referred by the public to the CyberTipline was found on  Internet Web sites. Since 1998, the center has received over 76,000 reports  of child pornography, of which 77 percent concerned Web sites, and only  1 percent concerned peer-to-peer networks. Web site referrals have grown  from about 1,400 in 1998 to over 26,000 in 2002—or about a nineteenfold  increase. NCMEC did not track peer-to-peer referrals until 2001. In 2002,  peer-to-peer referrals increased more than fourfold, from 156 to 757,  reflecting the increased popularity of file-sharing programs.
section_title: Juvenile Users of Peer-to-Peer Applications May Be Inadvertently Exposed to Pornography
paragraphs: Juvenile users of peer-to-peer networks face a significant risk of  inadvertent exposure to pornography when searching and downloading  images. In a search using innocuous keywords likely to be used by  juveniles searching peer-to-peer networks (such as names of popular  singers, actors, and cartoon characters), almost half of the images  downloaded were classified as adult or cartoon pornography. Juvenile  users may also be inadvertently exposed to child pornography through  such searches, but the risk of such exposure is smaller than that of  exposure to pornography in general.
To document the risk of inadvertent exposure of juvenile users to  pornography, the Customs CyberSmuggling Center performed KaZaA  searches using innocuous keywords that would likely be used by juveniles.  The center image searches used three keywords representing the names of  a popular female singer, child actors, and a cartoon character. A center  analyst performed the search, retrieval, and analysis of the images, each of  which was classified into one of five categories: child pornography, child  erotica, adult pornography, cartoon pornography, or nonpornographic.  The searches produced 157 files, some of which were duplicates. The  analyst was able to download 177 images from the 157 files identified  through the search.
As shown in figure 3, our analysis of the CyberSmuggling Center’s  classification of the 177 downloaded images determined that 61 images  contained adult pornography (34 percent), 24 images consisted of cartoon  pornography (14 percent), 13 images contained child erotica (7 percent),  and 2 images (1 percent) contained child pornography. The remaining 77  images were classified as nonpornographic.
section_title: Federal Law Enforcement Agencies Are Beginning to Focus Resources on Child Pornography on Peer- to-Peer Networks
paragraphs: Because law enforcement agencies do not track the resources dedicated to  specific technologies used to access and download child pornography on  the Internet, we were unable to quantify the resources devoted to  investigations concerning peer-to-peer networks. These agencies  (including the FBI, CEOS, and Customs) do devote significant resources to  combating child exploitation and child pornography in general. Law  enforcement officials told us, however, that as tips concerning child  pornography on the peer-to-peer networks increase, they are beginning to  focus more law enforcement resources on this issue.
In fiscal year 2002, the key organizations involved in combating child  pornography on peer-to-peer networks reported the following levels of  funding:    NCMEC received about $12 million for its congressionally mandated role  as the national resource center and clearinghouse. NCMEC also received  about $10 million for law enforcement training and about $3.3 million for  the Exploited Child Unit and the promotion of its CyberTipline. From the  appropriated amounts, NCMEC allocated $916,000 to combat child  pornography and referred 913 tips concerning peer-to-peer networks to  law enforcement agencies.
The FBI allocated $38.2 million and 228 agents and support personnel to  combat child pornography through its Innocent Images unit. Since fiscal  year 1996, the Innocent Image National Initiative opened 7,067 cases,  obtained 1,811 indictments, performed 1,886 arrests, and secured 1,850  convictions or pretrial diversions in child pornography cases. According to  FBI officials, they are aware of the use of peer-to-peer networks to  disseminate child pornography and have efforts under way to work with  some of the peer-to-peer companies to solicit their cooperation in dealing  with this issue.
CEOS allocated $4.38 million and 28 personnel to combat child  exploitation and obscenity offenses. It has recently launched an effort, the  High Tech Investigative Unit, dealing with investigating any Internet  medium that distributes child pornography, including peer-to-peer  networks.
Customs allocated $15.6 million and over 144,000 hours to combating child  exploitation and obscenity offenses. The CyberSmuggling Center is  beginning to actively monitor the file sharing of child pornography on  peer-to-peer networks and is devoting one half-time investigator to this  effort. As of December 16, 2002, the center has sent 21 peer-to-peer  investigative leads to the field offices for follow-up action. Four of these  leads have search warrants pending, two have been referred to local law  enforcement, and five have been referred to foreign law enforcement  agencies.
In addition, to facilitate the identification of the victims of child  pornographers, the CyberSmuggling Center is devoting resources to the  National Child Victim Identification Program, a consolidated information  system containing seized images that is designed to allow law enforcement  officials to quickly identify and combat the current abuse of children  associated with the production of child pornography. The system’s  database is being populated with all known and unique child pornographic  images obtained from national and international law enforcement sources  and from CyberTipline reports filed with NCMEC. It will initially hold over  100,000 images that have been collected by federal law enforcement  agencies from various sources, including old child pornography  magazines. According to Customs officials, this information will help,  among other things, to determine whether actual children were used to  produce child pornography images by matching them with images of  children from magazines published before modern imaging technology  was invented. Such evidence can be used to counter the assertion that  only virtual children appear in certain images.
The system is housed at the Customs CyberSmuggling Center and is to be  accessed remotely in “read only” format by the FBI, CEOS, the U.S. Postal  Inspection Service, and NCMEC. An initial version of the system was  deployed at the Customs CyberSmuggling Center in September 2002; the  system became operational in January 2003.
section_title: Conclusions
paragraphs: It is easy to access and download child pornography on peer-to-peer  networks. Juvenile users of peer-to-peer networks also face a significant  risk of inadvertent exposure to pornography, including child pornography.  We were unable to determine the extent of federal law enforcement  resources available for combating child pornography on peer-to-peer  networks; the key law enforcement agencies devote resources to  combating child exploitation and child pornography in general, but they do  not track the resources dedicated to peer-to-peer technologies in  particular.
section_title: Agency Comments and Our Evaluation
paragraphs: The Assistant Attorney General, Criminal Division, Department of Justice,  provided written comments on a draft of this report, which are reprinted  in appendix III. The Department of Justice agreed with the report’s  findings, provided additional information on the mission and capabilities  of the High Tech Investigative Unit (part of its Criminal Division’s Child  Exploitation and Obscenity Section), and offered comments on the  description and purpose of Customs’ National Child Victim Identification  Program. In response, we have revised our report to add these  clarifications. We also received written technical comments from the  Department of Justice, which we have incorporated as appropriate.
We received written technical comments from the Assistant Director,  Office of Inspection, U.S. Secret Service, and from the Acting Director,  Office of Planning, U.S. Customs Service. Their comments have been  incorporated in the report as appropriate.
As agreed with your office, unless you publicly announce the contents of  this report earlier, we plan no further distribution until 30 days from the  report date. At that time, we will send copies of this report to the  Chairmen and Ranking Minority Members of other Senate and House  committees and subcommittees that have jurisdiction and oversight  responsibility for the Departments of Justice and the Treasury. We will  also send copies to the Attorney General and to the Secretary of the  Treasury. Copies will be made available to others on request. In addition,  this report will be available at no charge on the GAO Web site at  http://www.gao.gov.
If you have any questions concerning this report, please call me at (202)  512-6240 or Mirko J. Dolak, Assistant Director, at (202) 512-6362. We can  be also reached by E-mail at koontzl@gao.gov and dolakm@gao.gov,  respectively. Key contributors to this report were Barbara S. Collier,  James M. Lager, Neelaxi V. Lakhmani, James R. Sweetman, Jr., and Jessie  Thomas.
section_title: Appendix I: Appendix I: Objectives, Scope, Appendix I: Objectives, Scope, and Methodology
paragraphs: determine the ease of access to child pornography on peer-to-peer    assess the risk of inadvertent exposure of juvenile users of peer-to-peer  networks to pornography, including child pornography, and    determine the extent of federal law enforcement resources available for  combating child pornography on peer-to-peer networks.
To determine the availability of child pornography on peer-to-peer  networks, we used a popular peer-to-peer application—KaZaA—to search  for and identify image files that appear to be child pornography. Our  analysts used keywords provided by the Customs CyberSmuggling Center.  These keywords were intended to identify pornographic images; examples  of the keywords include preteen, underage, and incest.
Once the names and titles of image files were gathered, we classified and  analyzed them based on file names and keywords. Each file was classified  as child pornography, adult pornography, or nonpornographic. For a file to  be considered possible child pornography, the title, file name, or both had  to include at least one word with a sexual connotation and an age-related  keyword indicating that the subject is a minor. Files depicting adult  pornography included any file that had words of a sexual nature in the title  or file name. No files were downloaded for this analysis.
To determine the ease of access, we used three keywords from the initial  list to perform another search. The resulting files were downloaded, saved,  and analyzed by a Customs agent. Because child pornography cannot be  accessed legally other than by law enforcement agencies, we relied on  Customs to download and analyze files. Our own analyses were based on  keywords and file names only. The Customs agent classified each of the  downloaded files into one of four categories: child pornography, child  erotica, adult pornography, or nonpornographic. The user with the largest  number of shared files that appeared to be child pornography was also  identified, and the shared folder was captured. The titles and names of  files in the user’s shared directory were then analyzed and classified by a  GAO analyst using the same classification criteria used in original analysis.
To assess the risk of inadvertent exposure of juvenile users of peer-to-peer  networks to pornography, a CyberSmuggling Center analyst conducted  another search using three keywords that are names of popular celebrities  and a cartoon character. The Customs analyst performed the search,  retrieval, and analysis of the images. Each of the images downloaded was  classified into one of five categories: adult pornography, child  pornography, child erotica, cartoon pornography, or nonpornographic.
To determine what federal law enforcement resources were allocated to  combating child pornography on peer-to-peer networks, we obtained  resource allocation data and interviewed officials at the U.S. Customs  Service, the Department of Justice’s Child Exploitation and Obscenity  Section, and the Federal Bureau of Investigation. We also received  information about what resources were being allocated to combat child  pornography from the U.S. Secret Service and the National Center for  Missing and Exploited Children.
We performed our work between July and October 2002 at the U.S. Secret  Service in Baltimore, Maryland, and the U.S. Customs Service, Customs  CyberSmuggling Center, in Fairfax, Virginia, under the Department of the  Treasury; and at the Child Exploitation and Obscenity Section and the  Federal Bureau of Investigation, under the Department of Justice, in  Washington, D.C. We also worked with the National Center for Missing  and Exploited Children in Alexandria, Virginia. Our work was conducted  in accordance with generally accepted government auditing standards.
section_title: Appendix II: Description of File Sharing and Peer-to-Peer Networks
paragraphs: Peer-to-peer file-sharing programs represent a major change in the way  Internet users find and exchange information. Under the traditional  Internet client/server model, the access to information and services is  accomplished by the interaction between users (clients) and servers— usually Web sites or portals. A client is defined as a requester of services,  and a server is defined as the provider of services. Unlike the traditional  model, the peer-to-peer model enables consenting users—or peers—to  directly interact and share information with each other without the  intervention of a server. A common characteristic of peer-to-peer  programs is that they build virtual networks with their own mechanisms  for routing message traffic.
The ability of peer-to-peer networks to provide services and connect users  directly has resulted in a large number of powerful applications built  around this model. These range from the SETI@home network (where  users share the computing power of their computers to search for  extraterrestrial life) to the popular KaZaA file-sharing program (used to  share music and other files).
As shown in figure 4, there are two main models of peer-to-peer networks:  (1) the centralized model, based on a central server or broker that directs  traffic between individual registered users, and (2) the decentralized  model, based on the Gnutella network, in which individuals find and  interact directly with each other.
As shown in figure 4, the centralized model relies on a central  server/broker to maintain directories of shared files stored on the  respective computers of the registered users of the peer-to-peer network.  When Bob submits a request for a particular file, the server/broker creates  a list of files matching the search request by checking the request with its  database of files belonging to registered users currently connected to the  network. The broker then displays that list to Bob, who can then select the  desired file from the list and open a direct link with Alice’s computer,  which currently has the file. The download of the actual file takes place  directly from Alice to Bob.
The broker model was used by Napster, the original peer-to-peer network,  facilitating mass sharing of copyrighted material by combining the file  names held by thousands of users into a searchable directory that enabled  users to connect with each other and download MP3 encoded music files.  The broker model made Napster vulnerable to legal challenges and  eventually led to its demise in September 2002.
Although Napster was litigated out of existence and its users fragmented  among many alternative peer-to-peer services, most current-generation  peer-to-peer networks are not dependent on the server/broker that was the  central feature of the Napster service, so, according to Gartner, these  networks are less vulnerable to litigation from copyright owners.
In the decentralized model, no brokers keep track of users and their files.  To share files using the decentralized model, Ted starts with a networked  computer equipped with a Gnutella file-sharing program, such as KaZaA or  BearShare. Ted connects to Carol, Carol to Bob, Bob to Alice, and so on.  Once Ted’s computer has announced that it is “alive” to the various  members of the peer network, it can search the contents of the shared  directories of the peer network members. The search request is sent to all  members of the network, starting with Carol, who will each in turn send  the request to the computers to which they are connected, and so forth. If  one of the computers in the peer network (say, for example, Alice’s) has a  file that matches the request, it transmits the file information (name, size,  type, etc.) back through all the computers in the pathway towards Ted,  where a list of files matching the search request appears on Ted’s  computer through the file-sharing program. Ted will then be able to open a  connection with Alice and download the file directly from Alice’s  computer.
One of the key features of Napster and the current generation of  decentralized peer-to-peer technologies is their use of a virtual name space  (VNS). A VNS dynamically associates user-created names with the Internet  address of whatever Internet-connected computer users happen to be  using when they log on. The VNS facilitates point-to-point interaction  between individuals, because it removes the need for users and their  computers to know the addresses and locations of other users; the VNS  can, to certain extent, preserve users’ anonymity and provide information  on whether a user is or is not connected to the Internet at a given  moment.
The file-sharing networks that result from the use of peer-to-peer  technology are both extensive and complex. Figure 5 shows a map or  topology of a Gnutella network whose connections were mapped by a  network visualization tool. The map, created in December 2000, shows  1,026 nodes (computers connected to more than one computer) and 3,752  edges (computers on the edge of the network connected to a single  computer). This map is a snapshot showing a network in existence at a  given moment; these networks change constantly as users join and depart  them.
section_title: Appendix III: Comments from the Department of Justice
section_title: Glossary
paragraphs: Operating at bandwidths markedly greater than that provided by telephone  networks. Broadband networks can carry digital videos or a massive  quantity of data simultaneously. In the on-line environment, the term is  often used to refer to Internet connections provided through cable or DSL  (digital subscriber line) modems.
A file-sharing program for Gnutella networks. BearShare supports the  trading of text, images, audio, video, and software files with any other user  of the network.
subsections: section_title: Broker
paragraphs: In the peer-to-peer environment, an intermediary computer that  coordinates and manages requests between client computers.
section_title: Cartoon pornography
paragraphs: Images of cartoon characters engaged in sexual activity.
section_title: Chat
paragraphs: Internet program enabling users to communicate through short written  messages. Some of the most popular chat programs are America Online’s  Instant Messenger and the Microsoft Network Messenger. See instant  messaging.
section_title: Child erotica
paragraphs: Sexually arousing images of children that are not considered  pornographic, obscene, or offensive.
A networking model in which a collection of nodes (client computers)  request and obtain services from a server node (server computer).
section_title: Gnutella
paragraphs: A file-sharing program based on the Gnutella protocol. Gnutella enables  users to directly share files with one another. Unlike Napster, Gnutella- based programs do not rely on a central server to find files.
section_title: Gnutella protocol
paragraphs: Decentralized group membership and search protocol, typically used for  file sharing. Gnutella file-sharing programs build a virtual network of  participating users.
section_title: Hypertext language (HTML)
paragraphs: The standard language (HyperText Markup Language) used to display  information on the Web. It uses tags embedded in text files to encode  instructions for formatting and displaying the information.
section_title: Instant messaging (IM)
paragraphs: A popular method of Internet communication that allows for an  instantaneous transmission of messages to other users who are logged into  the same instant messaging service. America Online’s Instant Messenger  and the Microsoft Network Messenger are among the most popular instant  messaging programs (see chat).
section_title: Internet relay chat (IRC)
paragraphs: Internet chat application allowing real-time conversations to take place via  software, text commands, and channels. Unlike the Web-based IM, IRC  requires special software and knowledge of technical commands (see  chat).
Internet Protocol address. A number that uniquely identifies a computer  connected to the Internet to other computers.
A file-sharing program using a proprietary peer-to-peer protocol to share  files among users on the network. Through a distributed self-organizing  network, KaZaA requires no broker or central server like Napster.
A file-sharing program running on Gnutella networks. It is open standard  software running on an open protocol, free for the public to use.
section_title: Morpheus
paragraphs: A file-sharing application using the KaZaA peer-to-peer protocol to share  files among users on the network.
section_title: Morphing
paragraphs: A process whereby one image is gradually transformed into a second  image.
Moving Pictures Experts Group (MPEG) MPEG-1 Audio Layer-3. A widely  used standard for compressing and transmitting music in digital format  across Internet. MP3 can compress file sizes at a ratio of about 10:1 while  preserving sound quality.
section_title: Newsgroups
paragraphs: Discussion groups on Usenet, varying in topic from technical to bizarre.  There are over 80,000 newsgroups organized by major areas or domains.  The major domains are alt (any conceivable topic, including pornography);  biz (business products and services); rec (games and hobbies); comp  (computer hardware and software); sci (sciences); humanities (art and  literature); soc (culture and social issues); misc (miscellaneous, including  employment and health); and talk (debates on current issues). See Usenet.
section_title: Node
paragraphs: A computer or a device that is connected to a network. Every node has a  unique network address.
section_title: Peer
paragraphs: A network node that may function as a client or a server. In the peer-to- peer environment, peer computers are also called servents, since they  perform tasks associated with both servers and clients.
section_title: Server
paragraphs: A computer that interconnects client computers, providing them with  services and information; a component of the client-server model. A Web  server is one type of server.
Search for extraterrestrial intelligence at home. A distributed computing  project, SETI@home uses data collected by the Arecibo Telescope in  Puerto Rico. The project takes advantage of the unused computing  capacity of personal computers. As of February 2000, the project  encompassed 1.6 million participants in 224 countries.
section_title: Topology
paragraphs: The general structure—or map—of a network. It shows the computers and  the links between them.
section_title: Usenet
paragraphs: A bulletin board system accessible through the Internet containing more  than 80,000 newsgroups. Originally implemented in 1979, it is now  probably the largest decentralized information utility in existence (see  newsgroups).
section_title: Virtual
paragraphs: Having the properties of x while not being x. For example, “virtual reality”  is an artificial or simulated environment that appears to be real to the  casual observer.
section_title: Virtual name space (VNS)
paragraphs: Internet addressing and naming system. In the peer-to-peer environment,  VNS dynamically associates names created by users with the IP addresses  assigned by their Internet services providers to their computers.
section_title: World Wide Web
paragraphs: A worldwide client-server system for searching and retrieving information  across the Internet. Also known as WWW or the Web.