Testimony 

Before the Subcommittee on Commerce, 

Trade, and Consumer Protection, 

Committee on Energy and Commerce, 

House of Representatives 

United States General Accounting Office 

GAO

For Release on Delivery 

Expected at 10:00 a.m. EDT 

Thursday, May 6, 2004 FILE SHARING 

PROGRAMS 

Users of Peer-to-Peer 

Networks Can Readily 

Access Child Pornography 

Statement of Linda D. Koontz 

Director, Information Management Issues 

GAO-04-757T 
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 (see the figure below). 

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 an increase of more than 

fivefold—from 156 in 2001 to 840 in 2003. Although the numbers are as yet 

small by comparison to those for other sources (45,035 reports of child 

pornography on Web sites in 2003), 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 peerto-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. 

Classification of Images Downloaded through Peer-to-Peer File-Sharing Program 

FILE-SHARING PROGRAMS 

Users of Peer-to-Peer Networks Can 

Readily Access Child Pornography 

www.gao.gov/cgi-bin/getrpt?GAO-04-757T 

To view the full testimony, click on the link 

above. 

For more information, contact Linda Koontz at 

(202) 512-6240 or koontzl@gao.gov. 

Highlights of GAO-04-757T, a testimony 

before the Subcommittee on Commerce, 

Trade, and Consumer Protection, 

Committee on Energy and Commerce, 

House of Representatives 

May 6, 2004

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 peerto-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. Today’s 

testimony is based on GAO’s report 

on the results of that work (GAO03-351).

Because child pornography cannot 

be accessed legally other than by 

law enforcement agencies, GAO 

worked with the Customs CyberSmuggling Center in performing 

searches: Customs downloaded 

and analyzed image files, and GAO 

performed analyses based on 

keywords and file names only. 
Page 1 GAO-04-757T 

Mr. Chairman and Members of the Subcommittee: 

Thank you for inviting us to discuss our work on the availability of child 

pornography on peer-to-peer networks. 

In recent years, child pornography has become increasingly available as it 

has migrated from magazines, photographs, and videos to the World Wide 

Web. As you know, a great strength of the Internet is that it includes a 

wide range of search and retrieval technologies that make finding 

information fast and easy. However, this capability also makes it easy to 

access, disseminate, and trade pornographic images and videos, including 

child pornography. As a result, child pornography has become accessible 

through Web sites, chat rooms, newsgroups, and the increasingly popular 

peer-to-peer technology, a form of networking that allows direct 

communication between computer users so that they can access and share 

each other’s files (including images, video, and software). 

My testimony today is based on our report on the availability of child 

pornography on peer-to-peer networks. 1

 As requested, I will summarize 

the results of our work 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. 

We also include an attachment that briefly discusses how peer-to-peer file 

sharing works. 

It is easy to access and download child pornography over peer-to-peer 

networks. We used KaZaA, a popular peer-to-peer file-sharing program, 2

 to 

search for image files, using 12 keywords known to be associated with 

 1

U.S. General Accounting Office, File-Sharing Programs: Peer-to-Peer Networks Provide 

Ready Access to Child Pornography, GAO-03-351 (Washington, D.C.: Feb. 20, 2003). 

2

Other popular peer-to-peer applications include Gnutella, BearShare, LimeWire, and 

Morpheus. 

Results in Brief 
Page 2 GAO-04-757T 

child pornography on the Internet.3 Of 1,286 items identified in our search, 

about 42 percent were associated with child pornography images. The 

remaining items included 34 percent classified as adult pornography and 

24 percent as nonpornographic. In another KaZaA search, the Customs 

CyberSmuggling Center used three keywords to search for and download 

child pornography image files. This search identified 341 image files, of 

which about 44 percent were classified as child pornography and 29 

percent as adult pornography. The remaining images were classified as 

child erotica4

 (13 percent) or other (nonpornographic) images (14 

percent). These results are consistent with observations of the National 

Center for Missing and Exploited Children, which has stated that peer-topeer technology is increasingly popular for the dissemination of child 

pornography. Since 2001, when the center began to track reports of child 

pornography on peer-to-peer networks, such reports have increased more 

than fivefold—from 156 in 2001 to 840 in 2003. 

When searching and downloading images on peer-to-peer networks, 

juvenile users can be inadvertently exposed to pornography, including 

child pornography. In searches on innocuous keywords likely to be used 

by juveniles, we obtained images that included a high proportion of 

pornography: in our searches, the retrieved images included adult 

pornography (34 percent), cartoon pornography5

 (14 percent), and child 

pornography (1 percent); another 7 percent of the images were classified 

as child erotica. 

We could not quantify the extent of federal law enforcement resources 

available for combating child pornography on peer-to-peer networks. Law 

enforcement agencies that work to combat child exploitation and child 

pornography do not track their resource use according to specific Internet 

technologies. However, law enforcement officials told us that, as they 

receive more tips concerning child pornography on peer-to-peer networks, 

they are focusing more resources in this area. 

 3

The U.S. Customs CyberSmuggling Center assisted us in this work. Because child 

pornography cannot be accessed legally other than by law enforcement agencies, we relied 

on Customs to download and analyze image files. We performed analyses based on titles 

and file names only. 

4

Erotic images of children that do not depict sexually explicit conduct. 

5

Images of cartoon characters depicting sexually explicit conduct. 
Page 3 GAO-04-757T 

Child pornography is prohibited by federal statutes, which provide for civil 

and criminal penalties for its production, advertising, possession, receipt, 

distribution, and sale.6

 Defined by statute as the visual depiction of a 

minor—a person under 18 years of age—engaged in sexually explicit 

conduct,7

 child pornography is unprotected by the First Amendment,8 as it 

is intrinsically related to the sexual abuse of children. 

In the Child Pornography Prevention Act of 1996,9

 Congress sought to 

prohibit images that are or appear to be “of a minor engaging in sexually 

explicit conduct” or are “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.” In 2002, the Supreme Court struck down this legislative attempt 

to ban “virtual” child pornography10 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 of prosecuting those who produce and 

possess child pornography. Defendants may claim that pornographic 

images are of “virtual” children, thus requiring the government to establish 

that the children shown in these digital images are real. Recently, 

Congress enacted the PROTECT Act,11 which attempts to address the 

constitutional issues raised in The Free Speech Coalition decision.12

 6

See chapter 110 of Title 18, United States Code. 

7

See 18 U.S.C. § 2256(8). 

8

See New York v. Ferber, 458 U.S. 747 (1982). 

9

Section 121, P.L. 104-208, 110 Stat. 3009-26. 

10According to the Justice Department, rapidly advancing technology has raised the 

possibility of creating images of child pornography without the use of a real child (“virtual” 

child pornography). Totally virtual creations would be both time-intensive and, for now, 

prohibitively costly to produce. However, the technology has led to a ready defense (the 

“virtual” porn defense) against prosecution under laws that are limited to sexually explicit 

depictions of actual minors. Because the technology exists today to alter images to 

disguise the identity of the real child or make the image seem computer-generated, 

producers and distributors of child pornography may try to alter depictions of actual 

children in slight ways to make them appear to be “virtual” (as well as unidentifiable), 

thereby attempting to defeat prosecution. Making such alterations is much easier and 

cheaper than building an entirely computer-generated image. 

11Public Law No. 108-21 (Apr. 30, 2003). 

12S. Rep. No. 108-2, at 13 (2003). 

Background 
Page 4 GAO-04-757T 

Historically, pornography, including child pornography, tended to be 

found mainly in photographs, magazines, and videos.13 With the advent of 

the Internet, however, both the volume and the nature of available child 

pornography have changed significantly. 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 led to a proliferation 

of child pornography on the Internet. 

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.14

Today, child pornography is available through virtually every Internet 

technology (see table 1). 

 13John Carr, Theme Paper on Child Pornography for the 2nd World Congress on 

Commercial Sexual Exploitation of Children, NCH Children’s Charities, Children & 

Technology Unit (Yokohama, 2001). 

(http://www.ecpat.net/eng/Ecpat_inter/projects/monitoring/wc2/yokohama_theme_child_p

ornography.pdf)

14Frederick E. Allen, “When Sex Drives Technological Innovation and Why It Has to,” 

American Heritage Magazine, vol. 51, no. 5 (September 2000), p. 19. 

(http://www.plannedparenthood.org/education/updatearch.html) 

Allen notes that pornographers have driven the development of some of the Internet 

technologies, including the development of systems used to verify on-line financial 

transactions and that of digital watermarking technology to prevent the unauthorized use 

of on-line images. 

The Internet Has Emerged 

as the Principal Tool for 

Exchanging Child 

Pornography 
Page 5 GAO-04-757T 

Table 1: Internet Technologies Providing Access to Child Pornography 

Technology Characteristics 

World Wide Web Web sites provide on-line access to text and multimedia materials identified and 

accessed through the uniform resource locator (URL). 

Usenet A distributed electronic bulletin system, Usenet offers over 80,000 newsgroups, with 

many newsgroups dedicated to sharing of digital images. 

Peer-to-peer file-sharing programs Internet applications operating over peer-to-peer networks enable direct 

communication between users. Used largely for sharing of digital music, images, and 

video, peer-to-peer applications include BearShare, Gnutella, LimeWire, and KaZaA. 

KaZaA is the most popular, with over 3 million KaZaA users sharing files at any time. 

E-mail E-mail allows the transmission of messages over a network or the Internet. Users can 

send E-mail to a single recipient or broadcast it to multiple users. E-mail supports the 

delivery of attached files, including image files. 

Instant messaging Instant messaging is not a dial-up system like the telephone; it requires that both 

parties be on line at the same time. AOL’s Instant Messenger and Microsoft’s MSN 

Messenger and Internet Relay Chat are the major instant messaging services. Users 

may exchange files, including image files. 

Chat and Internet Relay Chat Chat technologies allow computer conferencing using the keyboard over the Internet 

between two or more people. 

Source: GAO. 

Among the principal channels for the distribution of child pornography are 

commercial Web sites, Usenet newsgroups, and peer-to-peer networks.15

Web sites. According to recent estimates, there are about 400,000 

commercial pornography Web sites worldwide,16 with some of the sites 

selling pornographic images of children. The child pornography trade on 

the Internet is not only profitable, it has a worldwide reach: recently a 

child pornography ring was uncovered 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. 

 15According to Department of Justice officials, other forums and technologies are used to 

disseminate pornography on the Internet. These include Web portal communities such as 

Yahoo! Groups and MSN Groups, as well as file servers operating on Internet Relay Chat 

channels. 

16Dick Thornburgh and Herbert S. Lin, editors, Youth, Pornography, and The Internet, 

National Academy Press (Washington, D.C.: 2002). 

(http://www.nap.edu/html/youth_internet/)
Page 6 GAO-04-757T 

Usenet. Usenet newsgroups also provide 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. 

Peer-to-peer networks. Although peer-to-peer file-sharing programs are 

largely known for the extensive sharing of copyrighted digital music,17 they 

are emerging as a conduit for the sharing of pornographic images and 

videos, including child pornography. In a recent study by congressional 

staff,18 a single search for the term “porn” using a file-sharing program 

yielded over 25,000 files. 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.19

Table 2 shows the key national organizations and agencies that are 

currently involved in efforts to combat child pornography on peer-to-peer 

networks. 

 17According to the Yankee Group, a technology research and consulting firm, Internet users 

aged 14 and older downloaded 5.16 billion audio files in the United States via unlicensed 

file-sharing services in 2001. 

18Minority Staff, Children’s Access to Pornography through Internet File-Sharing 

Programs, Special Investigations Division, Committee on Government Reform, U.S. House 

of Representatives (July 27, 2001). 

(http://www.house.gov/reform/min/pdfs/pdf_inves/pdf_pornog_rep.pdf) 

19Michael D. Mehta, Don Best, and Nancy Poon, “Peer-to-Peer Sharing on the Internet: An 

Analysis of How Gnutella Networks Are Used to Distribute Pornographic Material,” 

Canadian Journal of Law and Technology, vol. 1, no. 1 (January 2002). 

(http://cjlt.dal.ca/vol1_no1/articles/01_01_MeBePo_gnutella.pdf)

Several Agencies Have 

Law Enforcement 

Responsibilities Regarding 

Child Pornography on 

Peer-to-Peer Networks 
Page 7 GAO-04-757T 

Table 2: Organizations and Agencies Involved with Peer-to-Peer Child Pornography Efforts 

Agency Unit Focus 

Nonprofit 

National Center for Missing 

and Exploited Children 

Exploited Child Unit Works with the Customs Service, Postal Service, and the FBI to 

analyze and investigate child pornography leads. 

Federal entities 

Department of Justice Federal Bureau of 

Investigationa

Proactively investigates crimes against children. Operates a national 

“Innocent Images Initiative” to combat Internet-related sexual 

exploitation of children. 

 Criminal Division, Child 

Exploitation and Obscenity 

Section 

Is a specialized group of attorneys who, among other things, prosecute 

those who possess, manufacture, or distribute child pornography. Its 

High Tech Investigative Unit actively conducts on-line investigations to 

identify distributors of obscenity and child pornography. 

Department of Homeland 

Security 

U.S. Customs Service 

CyberSmuggling Centera

, b 

Conducts international child pornography investigations as part of its 

mission to investigate international criminal activity conducted on or 

facilitated by the Internet. 

Department of the Treasury U.S. Secret Servicea Provides forensic and technical assistance in matters involving missing 

and sexually exploited children. 

Source: GAO. 

a

Agency has staff assigned to NCMEC. 

b

At the time of our review, the Customs Service was under the Department of the Treasury. Under the 

Homeland Security Act of 2002, it became part of the new Department of Homeland Security on 

March 1, 2003. 

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.20

 20According to the Secret Service, its staff assigned to NCMEC also includes an agent. 
Page 8 GAO-04-757T 

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).21

• 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 other organizations have responsibilities regarding child 

pornography: the Customs Service (now part of the Department of 

Homeland Security) and the Secret Service in the Department of the 

Treasury. 

• 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 

 21Two additional Justice agencies are involved in combating child pornography: the U.S. 

Attorneys Offices and the Office of Juvenile Justice and Delinquency Prevention. The 94 

U.S. Attorneys Offices can prosecute federal child exploitation-related cases; the Office of 

Juvenile Justice and Delinquency Prevention funds the Internet Crimes Against Children 

Task Force Program, which encourages multijurisdictional and multiagency responses to 

crimes against children involving the Internet. 
Page 9 GAO-04-757T 

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. 

Child pornography is easily shared and accessed through peer-to-peer filesharing programs. Our analysis of 1,286 titles and file names identified 

through KaZaA searches on 12 keywords22 showed that 543 (about 42 

percent) of the images had titles and file names associated with child 

pornography images.23 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. 

Figure 1: Classification of 1,286 Titles and File Names of Images Identified in KaZaA 

Search 

 22The 12 keywords were provided by the Cybersmuggling Center as examples known to be 

associated with child pornography on the Internet. 

23We categorized a file as child pornography if one keyword indicating a minor and one 

word with a sexual connotation occurred in either the title or file name. Files with sexual 

connotation in title or name but without age indicators were classified as adult 

pornography. 

Peer-to-Peer 

Applications Provide 

Easy Access to Child 

Pornography 
Page 10 GAO-04-757T 

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). 

Figure 2: Classification of 341 Images Downloaded through KaZaA 

Note: GAO analysis of data provided by the Customs CyberSmuggling Center. 

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 139,000 

reports of child pornography, of which 76 percent concerned Web sites, 

and only 1 percent concerned peer-to-peer networks. Web site referrals 
Page 11 GAO-04-757T 

have grown from about 1,400 in 1998 to over 45,000 in 2003—or about a 

thirty-two-fold increase. NCMEC did not track peer-to-peer referrals until 

2001. Between 2001 and 2003, peer-to-peer referrals increased more than 

fivefold, from 156 to 840, reflecting the increased popularity of file-sharing 

programs. 

Table 3: NCMEC CyberTipline Referrals to Law Enforcement Agencies, Fiscal Years 

1998–2003 

 Number of tips 

Technology 1998 1999 2000 2001 2002 2003

Web sites 1,393 3,830 10,629 18,052 26,759 45,035

E-mail 117 165 120 1,128 6,245 12,403

Peer-to-peer — — — 156 757 840

Usenet newsgroups & 

bulletin boards 531 987 731 990 993 1,128

Unknown 90 258 260 430 612 1,692

Chat rooms 155 256 176 125 234 786

Instant Messaging 27 47 50 80 53 472

File transfer protocol 25 26 58 64 23 13

Total 2,338 5,569 12,024 21,025 35,676 62,369

Source: Exploited Child Unit, National Center for Missing and Exploited Children. 

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 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 likely to be used by juveniles. The 

center’s 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. These 

searches produced 157 files, some of which were duplicates. From these 

157 files, the analyst was able to download 177 images. 

Juvenile Users of 

Peer-to-Peer 

Applications May Be 

Inadvertently 

Exposed to 

Pornography 
Page 12 GAO-04-757T 

Figure 3 shows our analysis of the CyberSmuggling Center’s classification 

of the 177 downloaded images. We 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. 

Figure 3: Classification of 177 Images of a Popular Singer, Child Actors, and a 

Cartoon Character Downloaded through KaZaA 

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. Table 4 shows the 

levels of funding related to child pornography issues that the primary 

organizations reported for fiscal year 2002, as well as a description of their 

efforts regarding peer-to-peer networks in particular. 

Federal Law 

Enforcement 

Agencies Are 

Beginning to Focus 

Resources on Child 

Pornography on Peerto-Peer Networks 
Page 13 GAO-04-757T 

Table 4: Resources Related to Combating Child Pornography on Peer-to-Peer Networks in 2002 

Organization Resourcesa Efforts regarding peer-to-peer networks 

National Center for Missing 

and Exploited Children 

$12 million to act as national resource center and 

clearinghouse for missing and exploited children 

$10 million for law enforcement training 

$3.3 million for the Exploited Child Unit and the 

CyberTipline 

$916,000 allocated to combat child pornography 

NCMEC referred 913 tips concerning peer-to-peer 

networks to law enforcement agencies. 

Federal Bureau of 

Investigation 

$38.2 million and 228 agents and support 

personnel for Innocent Images Unit 

According to FBI officials, they have efforts under 

way to work with some of the peer-to-peer 

companies to solicit their cooperation in dealing 

with the issue of child pornography. 

Justice Criminal Division, 

Child Exploitation and 

Obscenity Section 

$4.38 million and 28 personnel allocated to 

combating child exploitation and obscenity offenses

The High Tech Investigative Unit deals with 

investigating any Internet medium that distributes 

child pornography, including peer-to-peer 

networks. 

U.S. Customs Service 

CyberSmuggling Center 

$15.6 million (over 144,000 hours) allocated to 

combating child exploitation and obscenity 

offensesb

 

The center is beginning to actively monitor peer-topeer networks for child pornography, devoting one 

half-time investigator to this effort. As of December 

16, 2002, the center had sent 21 peer-to-peer 

investigative leads to field offices for follow-up. 

Sources: GAO and agencies mentioned. 

a

Dollar amounts are approximate. 

b

Customs was unable to separate the staff hours devoted or funds obligated to combating child 

pornography from those dedicated to combating child exploitation in general. 

An important new resource to facilitate the identification of the victims of 

child pornographers is the National Child Victim Identification Program, 

run by the CyberSmuggling Center. This resource is 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 collected by federal law 

enforcement agencies from various sources, including old child 

pornography magazines.24 According to Customs officials, this information 

will help, among other things, to determine whether actual children were 

 24According to federal law enforcement agencies, most of the child pornography published 

before 1970 has been digitized and made widely available on the Internet. 
Page 14 GAO-04-757T 

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, which became operational in January 2003,25 is housed at the 

Customs CyberSmuggling Center and can be accessed remotely in “read 

only” format by the FBI, CEOS, the U.S. Postal Inspection Service, and 

NCMEC. 

In summary, Mr. Chairman, our work shows that child pornography as 

well as adult pornography is widely available and accessible on peer-topeer networks. Even more disturbing, we found that peer-to-peer searches 

using seemingly innocent terms that clearly would be of interest to 

children produced a high proportion of pornographic material, including 

child pornography. The increase in reports of child pornography on peerto-peer networks suggests that this problem is increasing. As a result, it 

will be important for law enforcement agencies to follow through on their 

plans to devote more resources to this technology and continue their 

efforts to develop effective strategies for addressing this problem. 

Mr. Chairman, this concludes my statement. I would be pleased to answer 

any questions that you or other Members of the Subcommittee may have at 

this time. 

If you should have any questions about this testimony, please contact me 

at (202) 512-6240 or by E-mail at koontzl@gao.gov. Key contributors to this 

testimony were Barbara S. Collier, Mirko Dolak, James M. Lager, Neelaxi 

V. Lakhmani, James R. Sweetman, Jr., and Jessie Thomas. 

 25One million dollars has already been spent on the system, with an additional $5 million 

needed for additional hardware, the expansion of the image database, and access for all 

involved agencies. The 10-year lifecycle cost of the system is estimated to be $23 million. 

Contact and 

Acknowledgements 
Page 15 GAO-04-757T 

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, access to information and services is 

accomplished by interaction between clients—users who request 

services—and servers—providers of services, usually Web sites or portals. 

Unlike this 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.1

The ability of peer-to-peer networks to provide services and connect users 

directly has resulted in a large number2

 of powerful applications built 

around this model.3

 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 4,4

 there are two main models of peer-to-peer networks: 

(1) the centralized model, in which a central server or broker directs 

traffic between individual registered users, and (2) the decentralized 

 1

Matei Ripenau, Ian Foster, and Adriana Iamnitchi, “Mapping the Gnutella Network: 

Properties of Large Scale Peer-to-Peer Systems and Implication for System Design,” IEEE 

Internet Computing, vol. 6, no. 1 (January–February 2002). 

(people.cs.uchicago.edu/~matei/PAPERS/ic.pdf)

2

Zeropaid.com, a file-sharing portal, lists 88 different peer-to-peer file-sharing programs 

available for download. (http://www.zeropaid.com/php/filesharing.php) 

3

Geoffrey Fox and Shrideep Pallickara, “Peer-to-Peer Interactions in Web Brokering 

Systems,” Ubiquity, vol. 3, no. 15 (May 28–June 3, 2002) (published by Association of 

Computer Machinery). (http://www.acm.org/ubiquity/views/g_fox_2.html) 

4

Illustration adapted by Lt. Col. Mark Bontrager from original by Bob Knighten, “Peer-toPeer Computing,” briefing to Peer-to-Peer Working Groups (August 24, 2000), in Mark D. 

Bontrager, Peering into the Future: Peer-to-Peer Technology as a Model for Distributed 

Joint Battlespace Intelligence Dissemination and Operational Tasking, Thesis, School of 

Advanced Airpower Studies, Air University, Maxwell Air Force Base, Alabama (June 2001). 

Attachment: How File Sharing Works on 

Peer-to-Peer Networks 
Page 16 GAO-04-757T 

model, based on the Gnutella5 network, in which individuals find each 

other and interact directly. 

Figure 4: Peer-to-Peer Models 

As shown in figure 4, in the centralized model, a central server/broker 

maintains directories of shared files stored on the computers of registered 

users. When Bob submits a request for a particular file, the server/broker 

creates a list of files matching the search request by checking it against its 

database of files belonging to 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. 

This broker model was used by Napster, the original peer-to-peer network, 

facilitating mass sharing of material by combining the file names held by 

 5

According to LimeWire LLC, the developer of a popular file-sharing program, Gnutella was 

originally designed by Nullsoft, a subsidiary of America Online. The development of the 

Gnutella protocol was halted by AOL management shortly after the protocol was made 

available to the public. Using downloads, programmers reverse-engineered the software 

and created their own Gnutella software packages. 

(http://www.limewire.com/index.jsp/p2p)
Page 17 GAO-04-757T 

thousands of users into a searchable directory that enabled users to 

connect with each other and download MP3 encoded music files. Because 

much of this material was copyrighted, Napster as the broker of these 

exchanges was vulnerable to legal challenges,6

 which eventually led to its 

demise in September 2002. 

In contrast to Napster, most current-generation peer-to-peer networks are 

decentralized. Because they do not depend on the server/broker that was 

the central feature of the Napster service, these networks are less 

vulnerable to litigation from copyright owners, as pointed out by Gartner.7

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; members will, 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 can then open a 

connection with Alice and download the file directly from Alice’s 

computer.8

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.9

 The map, created in December 2000, shows 

 6

A&M Records v. Napster, 114 F.Supp.2d 896 (N.D. Cal. 2000). 

7

Lydia Leong, “RIAA vs.Verizon, Implications for ISPs,” Gartner (Oct. 24, 2002). 

8

LimeWire, Modern Peer-to-Peer File Sharing over the Internet. 

(http://www.limewire.com/index.jsp/p2p)

9

 Mihajlo A. Jovanovic, Fred S. Annexstein, and Kenneth A. Berman, Scalability Issues in 

Large Peer-to-Peer Networks: A Case Study of Gnutella, University of Cincinnati Technical 

Report (2001). (http://www.ececs.uc.edu/~mjovanov/Research/paper.html)
Page 18 GAO-04-757T 

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. 

Figure 5: Topology of a Gnutella Network 

One of the key features of many peer-to-peer technologies is their use of a 

virtual name space (VNS). A VNS dynamically associates user-created 
Page 19 GAO-04-757T 

names with the Internet address of whatever Internet-connected computer 

users happen to be using when they log on.10 The VNS facilitates point-topoint 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 a certain extent, preserve users’ anonymity and 

provide information on whether a user is or is not connected to the 

Internet at a given moment. Peer-to-peer users thus may appear to be 

anonymous; they are not, however. Law enforcement agents may identify 

users’ Internet addresses during the file-sharing process and obtain, under 

a court order, their identities from their Internet service providers. 

 10 S. Hayward and R. Batchelder, “Peer-to-Peer: Something Old, Something New,” Gartner 

(Apr. 10, 2001). 

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