选择: Privacy & Surveillance - 麻省理工学院人工智能研究专业

选择: Privacy & Surveillance
in a Once & Future Internet

Susan Landau

抽象的: The Internet’s original design provided a modicum of privacy for users; it was not always possible
to determine where a device was or who was using it. But a combination of changes, including “free” Internet
服务, increasing use of mobile devices to access the network, and the coming “Internet of Things” (sensors
everywhere) make surveillance much easier to achieve and privacy more dif½cult to protect. Yet there are also
technologies that enable communications privacy, including address anonymizers and encryption. 用于
such technologies complicate law-enforcement and national-security communications surveillance, but do
not completely block it. Privacy versus surveillance in Internet communications can be viewed as a complex set
of economic tradeoffs–for example, obtaining free services in exchange for a loss of privacy; and protecting
communications in exchange for a more expensive, and thus less frequently used, set of government investi –
gative techniques–and choices abound.

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

Electronic communications create challenges. 在

enabling citizens to connect at a distance, 他们会
appear to loosen governmental control. But signals
can be eavesdropped on and recorded, and commu-
nications surveillance gives tremendous power. 甚至
if the communication itself is encrypted, 社区 –
cations metadata–the who, 什么时候, where of a mes-
sage–are not. Anyone who can collect metadata has
vast opportunity to know who is where and connect –
ing with whom.

The ability to remotely eavesdrop has existed for
at least as long as electronic communications. 是-
cause a signal can be plucked from the air, 相当
than visibly tapped into, radio is easier to eavesdrop
on than are wired communications. In many ways,
the Internet has made such surveillance easier still.
The tremendous flexibility afforded by the network–
the medium supports applications as diverse as search
engines, 地图, online social networks (osns), Twit-
特尔, YouTube, Netflix, 优步, and moocs (大量的
Open Online Courses)–makes the Internet indis-
pensable to citizens and nations alike, and its signals

SUSAN LANDAU is Professor of Cy –
ber security Policy in the Department
of Social Science and Policy Studies
at Worcester Polytechnic Institute.
Previously, she served as Senior Staff
Privacy Analyst for Google and as
Distinguished Engineer at Sun Mi –
cro systems. She is the author of Sur –
veillance or Security? The Risks Posed by
New Wiretapping Technologies (2011)
and Privacy on the Line: The Politics
of Wiretapping and Encryption (和
Whit ½eld Dif½e, 1998; 转速. 编辑. 2007),
and contributed to the National Re-
search Council’s Bulk Collection of
Sig nals Intelligence: Technical Options
(2015).

provide rich content for anyone listening
在. This can include governments, suppliers
of the services, and eavesdroppers.

Yet it does not have to be that way. 康姆-
munications can be encrypted, 和, 喜欢
speech, they can be ephemeral. The record
of a communication’s path through a net-
work can be essentially undiscoverable.
There are many ways to provide Internet
通讯, some of which do not
impinge on privacy. This article is about
those choices.

It starts, as it often does, with the under-

lying technology. The Internet was devel-
oped as a medium for sharing data. Its ba-
sic architectural principles–to break data
into a numbered set of small packets and
transmit the packets as ef½ciently as pos-
sible–reflects that underlying premise.
Each packet is transmitted using the Inter –
net protocol (ip). Packets typically have
three parts. The header says where the pack-
et is from (the sender’s ip address), 在哪里
the packet is going (the receiver’s ip ad-
裙子), the type of communications proto –
坳 (电子邮件, Web page, 视频, 嗓音, 所以
在), and its position (packet number) 在
that particular transmission. The payload
–the actual content–follows. Finally a
trailer marks the end of a packet. Applica-
tions–an http connection to a Web page,
an email connection, a Voice over ip call
(voip)–are broken into packets and then
reassembled at the receiver’s end.

Mobility of devices means that the user’s
ip address at the café at 10 a.m. is different
from that in the seminar room at 11 a.m.
Each time the user connects back to the
网络, her ip address is transmitted to
her service provider. That is how Facebook
communications and your email reach her
even when she has moved locations and
her ip address has changed.
Ip location provides partial identi½ca –
的. While an ip address delimits a loca-

tion from which and to which packets are
transmitted, that address is, for a number
of reasons, not necessarily useful in iden-
计时. The ip address may be one used
temporarily, and without strong identi½ –
阳离子, such as at an Internet café or an
airport. Without ancillary information,
such an ip address may provide minimal
identifying information. Another reason
that an ip address may not provide de½ni-
tive identi½cation is that few routers along
the transmission check a sender’s address;
so spoo½ng an ip address is easy.1

Even if the ip address is correct, it may
not provide an investigator with informa-
tion to determine who is responsible for a
particular action.2 That is because in such
instances, the connecting machine may be
just a way station. 考虑, 例如,
DDoS attacks (Distributed Denial of Service
attacks), in which hundreds of thousands
of computers simultaneously send mes-
sages to an online service, overwhelming
it and taking it offline. The machines send –
ing these messages are simply intermedi-
aries that have been compromised them-
自己. ddos is an example of a multistage
攻击, in which a perpetrator in½ltrates
a series of machines to launch an attack.
Cyberexploits–theft of information from
networked systems–are also typically mul –
ti stage attacks. The ½rst machine to receive
the ex½ltrated data is often itself compro-
mised, and the stolen data will be quickly
moved from that machine to another and
another–a lengthy chain of compromised
machines–before the data end up in the
attacker’s hands. An investigation may lead
to the initial machine that was used in the
scam, but is unlikely to lead all the way to
the real attacker.3

The fact that ip addresses do not pro-
vide precise identity matters very little in
certain cases. Spoo½ng does not concern the
Recording Industry Association of Amer-
伊卡, which uses an ip address as a jumping-
off point for copyright infringement suits.4

苏珊
Landau

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

145 (1) 冬天 2016

选择:
Privacy &
Surveillance
in a Once
& 未来
互联网

ip addresses have also served law enforce –
ment as a starting point for investigations.5
They can also be useful in investigations in
which the participants’ addresses are re lat –
编辑; 例如, if they all work at Enron.
Since an ip address is typically not
enough to identify an individual, a user
browsing generic sites such as The New York
Times’ without logging in achieves some
匿名. Actions the user takes, 然而-
是, can alter that. 尤其, a series of
suf½ciently personal searches that can be
linked to each other may suf½ce to iden-
tify an individual.6

The point is that ip addresses have a
fungibility, at least when it comes to iden-
tity. They provide a starting point for link-
ing a person with an action, 但他们是
also insuf½cient to be de½nitive. 因此, ip
addresses can provide surveillance capa-
bilities and privacy; the speci½c circum-
stances determine which it might be.

Investigators often seek identity, 尽管
not necessarily at the level of an ip address.
Following users across the Internet became
important with the arrival of free services
such as Facebook, Google search, and Yik –
Yak. Such services are supported through
advertising. In this instance, identity does
not mean identifying a user in the sense of
“Alison Clark is visiting honda.com,” but
rather that the browser currently viewing
nytimes.com is the same that ran an In-
ternet search for compact cars earlier in the
天. This enables the search provider, 为了
例子, to serve a Honda ad on The New
York Times website that the user is browsing.
Identi½cation is derived through cookies
in the browser, not an ip address.

There are times when identity on the In-
ternet at the level of a person matters. A
bank does not particularly care what a user’s
ip address is, but if there’s a transaction
occurring, the bank seeks assurance that the
person is who she claims to be and wants
her to authenticate her identity at the bank’s

site. For many situations, including trans-
actions with high value, authentication con –
ducted within an application is suf½cient
proof of identity.

日益, identity is required for ac-
cessing services. Federated identity manage-
ment–facilitating access to different sites
once a user has been authenticated to an
“identity provider”–is one way to do this.
例如, a corporate login could permit
seamless electronic access to outsourced
services such as hr or travel booking; A
university login could allow access to elec-
tronic resources at a federated institution.
Some approaches to identity manage-
ment carefully protect privacy. One exam-
ple is Shibboleth, which is used for sharing
secured Web resources and services among
a consortium of universities, research labs,
publishers, and medical librar ies. To access
a resource, the user must establish her right
to it, such as by being a faculty member or
a student. The user’s id is shared only if
access to the resource requires it.7 Another
case of privacy-protective identity manage –
ment comes courtesy of the U.S. 治理-
蒙特, which employs private-sector iden-
tity providers for accessing government
web sites, but requires that the users’ infor –
mation be employed only for authentica-
的, audit, and complying with the law–
and not for ads or sharing with third par-
ties.8 So if a user is looking at Veterans Af-
fairs bene½ts and then at information about
sexually transmitted diseases, that informa –
tion should neither be tracked nor stored
by the identity provider.

Other systems take a very different ap-
普罗奇, using user data to entice services to
work with them. 因此, 例如, 什么时候
the Facebook login is used to authenticate
a user to an app, Facebook shares with the
app the user’s name and gender, 和亲-
vides a list of the user’s friends who also
use the application. This makes the Face-
book login valuable to the app, but not to
a user seeking privacy.

代达罗斯, 美国艺术学院学报 & 科学

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

The existing model of advertising and
tracking in exchange for services is not the
only possible model for the Internet. 一
alternative would be to charge for services:
a tenth of a cent for a search, a monthly
charge for email support, 等等. 和
there is no reason the two systems could
not coexist: charges for users seeking pri-
vacy-protective services, and an advertise-
and-track model for those who are indif-
ferent to the privacy issue or unable to pay.

By making the network indispensable to

daily life, the Internet drove the develop-
ment of smartphones. Most Internet ac-
cesses now occur through mobile devices,
a fact with profound implications for pri-
vacy and surveillance. While a laptop can
be “on” but not connected to the network
–functioning as a computer, not a com-
munications device–if a smartphone is
在 (and not in “airplane mode”), it will be
connected to the telephone network when –
ever the provider’s system is within range.
因此, a phone’s location, which is broad-
cast several times an hour to announce
“I am here,” is a relatively public piece of
信息. The phone’s connection is
through the nearest base station: the cell
tower closest to the user. As the user moves
to new locations, the phone connection is
“handed off” to the next base station. 那
is information that the phone network–
or an interceptor–will learn.

Where an individual is calling from, 或者
whom they called, may be much more in-
teresting than what they actually said;
communications metadata, 例如,
can reveal the structure of an organization.
One striking example of this type of anal –
ysis concerns the case of former Lebanese
Prime Minister Ra½k Hariri, who was as-
sassinated in Beirut in 2005, when a truck
bomb exploded near his motorcade.9 The
planning behind the assassination was
well-hidden, but analysis of cell phone
traf½c in Beirut and other locations exposed

a pattern of communications that revealed
who did it–and how.10

Desktops, laptops, and tablets are, 到
some extent, multiuser machines; 但
smart phones are more strictly associated
with individuals. 因此, just tracking the
phone’s location provides an extremely ac –
curate way of determining a phone’s user.11
Know the recipients of a person’s calls, 和
you can infer who she is and what is hap-
pening in her life: whether she has just lost
her job, her mother is ill, or her son has just
gone off to college. Because people carry
personal transmitters and receivers, 政府-
ernment investigators no longer need to
tail individuals and monitor phone booths
to capture conversations and movements;
they simply track mobile phones. 因为
communications patterns are so reveal-
英, if a government can fully surveil a na-
tion’s communications network, it can even
track “burner” phones (anonymous pre-
paid phones) through correlations in loca –
tion and use.

Governments are not the only ones fol-
lowing users’ locations; in fact they may be
collecting far less information than many
公司. To provide the Internet with
services for which smartphones are valued
–½nding a local restaurant and making
dinner reservations and then determining
the best route there–the phone must pro-
vide location information to the app. 这
is done through gps, which typically op-
erates on a resolution within ten meters.12
So the network provider knows where the
phone is and with which service the user
is communicating, while the app provider
learns phone location and what informa-
tion is delivered through the app.13

This is an interesting design choice in
location data tracking: Apple’s ios8 does
not allow apps to collect location informa –
tion when the app is not in use, but there
is no such restriction for Android phones
(当然, if location collection is shut off,
then Android apps cannot collect it). 这

苏珊
Landau

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

145 (1) 冬天 2016

选择:
Privacy &
Surveillance
in a Once
& 未来
互联网

latter situation might change: 二月里
2015, 美国. Federal Trade Commission
told app developers, “If you access users’
lo cations when they’re not using your app,
it’s a good idea to clearly disclose what
you’re doing and provide users with choic –
es.”14

The real gold in the Internet advertising
world is “conversion tracking,” learning
what customers do after clicking on an ad:
whether they bought the product or fol-
lowed up in another way (such as visiting
a product’s website). When the Web access,
user location, and payment are all on the
same device, it becomes even easier for an
Internet service and an advertiser to de-
termine an ad’s effectiveness. The phone
might not announce, “This is Alison Clark”
at the Honda dealership, but if her phone
shows an identi½er from the search she
实施, that provides the relevant in-
形成. 为此原因, companies are
at least as eager as governments to use
smartphones to track users.

With such interest in following the user

and such capabilities for surveillance, 是的 –
comes dif½cult to imagine that any privacy
is possible. Yet there are many technical
solutions for protecting privacy. It is par-
ticularly striking that there are even tech-
nical solutions for obscuring with whom
you are communicating. In the mid-1990s,
the Naval Research Laboratory began work
on a system that makes it dif½cult to de-
termine who is connecting with whom on
the Internet.15

The onion routing network, 通常
known as Tor, protects against traf½c anal –
ysis through deployment of a “Tor net-
工作,” a collection of servers with encryp –
tion and decryption software. A path is de –
termined for each communication, 哪个
is then routed through a network of Tor
节点 (servers) that strip off the encryption
“one layer at a time.” Encryption keys are
based on the nodes and route.

Anyone who is eavesdropping on Internet
traf½c can determine that one Tor node is
communicating with another. More spe –
ci½cally, if there is surveillance of connec –
tions to a website–such as who in Iran is
reading about international sanctions–
the interceptor will see a connection from
the Tor network to the forbidden website.
But the eavesdropper will not see the ip ad –
dress that initiated the Internet connec tion
unless the eavesdropper can view the entire
network at once and thus correlate times
and sizes for all network transmissions. 在
such cases, interceptors can de anonymize
Tor communications, but otherwise Tor
makes such identi½cation extremely dif½ –
cult.16 Browsers and instant messaging apps
can be used on the Tor net work, 使能
truly anonymous communication through
which it is infeasible for the receiver to de-
termine the original send er’s ip address.
It might be surprising that a U.S. 政府-
ernment agency supports anonymous In-
ternet accesses. But there are good reasons
for the government to seek such capabil-
实体. A military unit in a safe house in the
Middle East would not want to let the lo-
cal Internet service provider (isp) 知道
that it is communicating with the Naval
Academy in Annapolis, while an fbi agent
investigating a child pornography chat
room does not want to use an ip address
that resolves to “fbi.com.” So a system
that makes it appear that the Web connec-
tion is from somewhere else provides useful
investigative capability. Tor is widely avail –
able and popular with journalists, 人类-
rights workers, and others seeking privacy
沟通的. And it provides cover
for military personnel and law-enforce-
ment investigators, whose identities as U.S.
government employees are masked by the
system’s broader set of users.

In many ways, con½dentiality of com-
munications is simpler to achieve than pri –
vacy. Encryption–encoding messages so
that only the sender and receiver can read

代达罗斯, 美国艺术学院学报 & 科学

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

it–accomplishes this. But simple answers
belie simple understanding. By now it
should be clear that nothing about protect –
ing communications is entirely simple.

For a quarter-century, from the 1970s to
20世纪90年代末, 美国. government bat-
tled academia and industry over encryp-
tion used to support con½dentiality. 这
½ght came to a head during the “Crypto
Wars” two decades ago, at the dawn of the
Internet era. 在 1999, 欧盟
loosened its controls on the export of prod –
ucts with strong encryption; a few months
later the United States did the same.17 This
change made it much simpler to deploy
cryptography in commercial products.

While use of encryption for con½denti –
ality had been controlled, its use for au-
thentication–assurance that a person or
site is who they say they are–had not.
Https, the secure version of the http linking
协议, is used to authenticate a website
(例如, con½rming that the site is
bankofamerica.com and not an imposter
that is like bank0famerica.com) and en-
crypt com munications between a user and
the site. This protocol was essential for
electronic commerce, and was already de-
ployed by the mid- to late 1990s. 鉴于
https was widely deployed quite early for
ecommerce, it is surprising and somewhat
striking that Web mail, the service that
provides email through a browser, was not
similarly protected. Let us examine how
such services work.

Suppose a user with the email account
boris@yahoo.com is communicating with
another user, natasha@gmail.com. 什么时候
Boris sends an email to Natasha, he logs
on to his Yahoo! Mail account, writes his
message, hits send, and the mail travels to
Natasha’s Gmail account. She will read
his message once she logs onto the Gmail
server (many users, including those with
Android phones, are always logged on).
From the beginning, Web mail providers
used the https protocol when authenticat –

ing users to their accounts; this encrypted
the user password from the user’s browser
to the site. But for many years, 大的
Web mail providers–Gmail, Hotmail, Ya-
hoo! Mail–did not encrypt the connection
between the user and her mail account;
那是, the emails themselves traveled in the
clear between the user’s machine and the
提供者. Anyone eavesdropping on the In –
ternet connection between Boris and his
雅虎! Mail account, relatively easy to do,
could read Boris’s incoming and outgoing
mail. In response to the Snowden revela-
系统蒸发散, Google changed their connection to
a secure one, and other providers are fol-
lowing suit. Mail traveling between Na –
tasha’s computer and her Gmail account
are on an encrypted channel; interceptors
cannot read it.

But this change does not fully encrypt
the mail from Boris to Natasha. 虽然
systems began securing communications
between the user and the mail provider,
the communications themselves still are
not encrypted “end-to-end” from sender
to receiver. If Boris and Natasha both hap-
pen to be using Gmail, then their commu –
nication will be encrypted between Boris
and the Gmail server and between the
Gmail server and Natasha. Contents on the
Gmail servers are encrypted, but there will
be a time when Boris’s mail to Natasha is in
the clear at Google. That is because Google
uses the mail to serve ads and to provide
personalized services. 例如, a plane
reservation in an email account will trigger
a noti½cation in the Google Now app to in –
form the user about traf½c on her preferred
route to the airport.

There are other models for email, 一些
of which provide greater con½dentiality.
One such service was Lavabit. Mail on
Lavabit servers arrived encrypted and
stayed that way; they were decrypted only
when a user was reading the communica-
的. Users received keys through a secure
https connection.

苏珊
Landau

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

145 (1) 冬天 2016

选择:
Privacy &
Surveillance
in a Once
& 未来
互联网

Lavabit was shut down by owner Ladar
Levison after the U.S. government request –
ed the encryption key securing the https
connection between Lavabit and its users.
Although government investigators ap-
peared to be interested only in a single
user’s communications, giving up that key
would have allowed access to all https con –
连接, thus potentially exposing all cus –
tomer passwords. Levison felt that would
violate his privacy commitment to his cus –
tomers. Instead of doing so, he closed the
service.18

Another example of alternative privacy
protection is Off-the-Record (otr) chat.
Google’s otr chat does not store chat his-
tories in users’ accounts, or in the accounts
of the people with whom they are chatting.
But Google policy does not preclude stor-
ing the communications elsewhere.19 A
more protective version would be not to
store the communications whatsoever.
Even more protective would be not stor-
ing and providing encryption for the chat.
Most protective would be to encrypt using
a technique called forward secrecy, so that
even if the encryption key is compromised
at some point, no previously intercepted
messages can be decrypted.20 There are
otr systems that provide this level of se-
curity.21

Alternatives in designing applications
lead to varying degrees of privacy. 这样的
safe guards do not come for free. They cost
extra development time and can decrease
ef½ciency by preventing reuse of data in
other applications. 和, as Lavabit’s owner
discovered, sometimes privacy-protective
systems lead to conflicts with the govern-
ment.22

Encryption’s knotty issue is that legal ac –
cess to decrypted content may be granted
to an investigator, but technology prevents
such access. And although electronic com –
munications now provide much richer in-
vestigative information than ever before–
consider the Hariri case–sometimes con-

tent provides information that these oth-
er tools cannot. 有, 然而, a way
around this problem.

As the Snowden disclosures con½rmed,
national-security agencies may exploit vul –
nerabilities in communications devices to
ex ½ltrate data from targets.23 Such capabil –
ities are used not only by intelligence agen –
化学系, but by law enforcement as well.24 As
en cryption becomes increasingly common,
such “lawful hacking” will increasingly be
used when communications content can-
not be retrieved in other ways.25 It is no
silver bullet; a vulnerabilities approach is
more complex legally and technically, 和
more expensive than if unencrypted com-
munications can be made available.

The privacy situation is about to grow far

more dif½cult. While Internet transac-
tional information is remarkably revelato-
里, the information from sensors on tooth-
brushes, watches, 衣服, heart monitors,
phones–and everything else–will be many
times more so. Cheap sensors communi-
cating with the Internet will soon be every –
在哪里: sensors to measure tire pressure
and bridge structural health; sensors to re –
port on the freshness of food in the fridge,
the dampness in the soil, and the move-
ment of an elderly person at night; sensors
to determine whether the car driver or pas –
senger is making a call. The number of de-
vices from the Internet of Things (iot) 将要
dwarf the current number of devices con-
nected to the Internet.

A user has some control over whether
information on her smartphone is shared
with the app; she can always shut the ap-
plication off or completely remove it from
her phone. While in some cases–as with
smart toothbrushes–the user might have
the same capability, she is unlikely to be
provided with such control on many other
applications (such as tire sensors).

For security’s sake, one approach might be
enclaves: creating domains with extreme –

代达罗斯, 美国艺术学院学报 & 科学

乙

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

ly limited ability to communicate outside
a narrow realm. Consider the type of con-
nectivity a smart refrigerator should have.
Fully connecting to the Internet creates an
unnecessary security risk. The fridge needs
to be able to communicate with the man-
ufacturer for updates and with the owner
for the you-need-milk noti½cations. A
smart phone app that puts milk on the shop –
ping list does not need noti½cations di-
rectly from the fridge; it could do so instead
by accessing owner updates. Limiting in-
formation flows from sensors and con-
trolling where those data initially go pro-
vides a measure of privacy and security.
Enclaves are likely to be for systems of
similar purposes (medical devices, infra-
structure sensors). A patient-sensor net-
work in a hospital intensive care unit should
not be accessible outside that area, 尽管
a sensor network for medical research
might span wide geographies. In some cas-
英语, data can be aggregated before reaching
a larger network–such as combining data
from sensors on soil conditions within a
region–providing privacy to individuals.
Flows of information–which data are
shared with whom–will be determined by
enclaves.

Determining appropriate enclaves for
sensor networks–should the enclave for
medical research networks be strictly sep-
arate from that used for patient networks?
–is complex, but provides only a partial
solution for privacy. This is partly because
keeping enclaves truly separate remains a
dif½cult technical problem. “Car-hack” at –
tacks, such as when in 2010 researchers re –
motely took control of a car’s brakes and
引擎,26 were possible because enclaves
lacked clear separation. 此外, putting
tight legal and policy controls on the da-
ta’s use will be crucial for privacy.27
Communications between people at a

distance have never been entirely private.
Delivery is variable, seals can be broken,

messages decrypted.28 Communications
that were once ephemeral now have a trail,
and being anonymous in modern society
is no longer plausible. It not only means
eschewing the use of smartphones (和
credit cards, transit passes, 等等),
but also requiring companions to do the
相同的. You cannot hide from network de-
tection if your known companions’ phones
broadcast their whereabouts.

In the wake of the Snowden disclosures,
privacy-enhancing technologies such as
Tor, and Google and Apple’s encrypted
phones, in which decryption is only pos-
sible with the user key (尽管, 当然,
much of the data may also be stored else-
在哪里), have drawn much interest. Privacy-
enhancing technologies enable different
levels of ability to conceal identity and in-
crease the cost for monitors to determine
information about an individual, but data
collection is so vast that these tools are un-
likely to be suf½cient for people with spe –
ci½c needs to protect themselves, 包括-
ing journalists and human-rights workers,
as well as criminals, terrorists, and spies.
的确, serious efforts to defend against
electronic traces may only draw increased
attention from intelligence agencies or
other eavesdroppers.29

Privacy has always been about econom-
集成电路. How much does it cost to use Lavabit’s
encrypted email services instead of free
Gmail services? Or how much more does
it cost to use cash at the bookstore instead
of ordering over Amazon? On the flip side,
how many resources must be devoted to
investigations if communications are pro-
tected through privacy-protective technol –
ogies?

The Internet changed the equation in
var ious ways. In the initial development
of Internet applications, we tipped in one
方向, allowing collection and release
of massive amounts of information about
ourselves. Application design, 然而,
pro vides a plethora of possibilities. 作为

苏珊
Landau

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

145 (1) 冬天 2016

选择:
Privacy &
Surveillance
in a Once
& 未来
互联网

long as “free” is the model for Internet ser –
恶习, it is unlikely that the tracking in-
工业化的, developed to support Internet ad-
vertising, will disappear. The information
amassed by private industry, 包括
vast collection of data afforded through
the Internet of Things, will also be accessed
by governments.

Our current Internet design is a world in
which applications sometimes provide pri –
vacy-protective solutions for those who
want them. But these give only a modicum
of privacy. Changing the ease with which
surveillance can be performed, making it
more dif½cult to track user preferences and
活动, is largely a matter of choices. (的
课程, under some governments, 有
no such choices. But in the United States,
private industry is not required to know

who users are in order to provide them a
service.) Choices for more privacy-protec –
tive solutions can come from government
法规, and they can come from cus-
tomer demand. But such alternatives in
application design do exist.

Humans are a highly communicative
物种, and the Internet fed this aspect of
our nature. That the Internet grew spec-
tacularly alongside the terrorist attacks of
September 11th and their aftermath meant
that privacy, always on a societal pendu-
卢姆, largely suffered over the last decade
and a half. Now choices abound; we may
be reaching a time when the pendulum
swings back. But the market will only pro-
vide effective privacy-protective solutions
if enough users demand them.

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

尾注
1 Robert Beverly, Ryan Coga, and kc claffy, “Initial Longitudinal Analysis of ip Source Spoo½ng Ca-
pability on the Internet,” July 25, 2013, http://calhoun.nps.edu/bitstream/handle/10945/36775/
Beverly_Initial_Longitudinal_2013.pdf.

2 This discussion on the value of ip addresses for attribution is based on David Clark and Susan

Landau, “Untangling Attribution,” Harvard National Security Journal 2 (2) (2011): 25–40.

3 In the case of ddos attacks, the machine sending connection requests to the service has itself
been infected with malware. By examining isp logs, it will usually be possible to determine
from where it is receiving instructions to attack (flood the service with connection requests).
But determining which machine, or set of machines, are sending these instructions may be a
multistep process, since instructions may be laundered through several machines. A similar sit-
uation exists for data ex½ltration, with the wrinkle that the data can be followed only until they
reach a jurisdiction in which the trail is made opaque. For further discussion, see ibid.

4 This technique was successfully used by the riaa for a number of years, although determining
an infringing user from an ip address is not straightforward; see Recording Industry Association
of America, Inc. v. Verizon Internet Service, 351 F. 2ND 1229, 直流电. 电路 (2003). 自从 2012, a number
of rulings have gone against the riaa.

5 See Clark and Landau, “Untangling Attribution,” fn 3.
6 aol released information about users’ searches over a three-month period; identifying a par-
ticular user was not hard to do. See Michael Barbaro and Tom Zeller Jr., “A Face is Exposed for
aol Searcher No. 4417749,“ 纽约时报, 八月 9, 2006. The ability to link a set of
searches to a user requires ½rst being able to link the user to her searches.

7 右. L. 摩根, Scott Cantor, Steven T. Carmody, Walter Hoehn, and Kenneth J. Klingenstein,
“Federated Security: The Shibboleth Approach,” EDUCAUSE Quarterly 27 (4) (2004): 12–17.
8 Georgia Tech Research Institute, “gtri nstic Trustmark Pilot” (十月 7, 2014), https://
trustmark.gtri.gatech.edu/operational-pilot/trustmark-de½nitions/½cam-privacy-activity
-tracking-requirements-for-csps-and-bae-responders/1.0/.

代达罗斯, 美国艺术学院学报 & 科学

9 The case is currently being decided in the Hague by the un’s Special Tribunal for Lebanon.
10 The cell phone traf½c showed several groups coordinating actions while tracking Hariri through
Beirut, and possibly even conducting a dry run of the attack. See Ronen Bergman, “The Hezbollah
Connection,” New York Times Magazine, 二月 10, 2015.

11 Phillippe Golle and Kurt Partridge, “On the Anonymity of Home/Work Location Pairs,” in Per-
vasive Computing: 7th International Conference, Pervasive 2009, Nara, 日本, May 11–14, 2009, Pro-
ceedings, 编辑. Hideyuki Tokuda, Michael Beigl, Adrian Friday, A. J. Bernheim Brush, and Yoshito
Tobe (柏林: Springer Berlin Hedelberg, 2009), 390–397.

12 Matt Blaze, Testimony to the House Committee on the Judiciary Subcommittee on the Consti-
tution, 公民权利, and Civil Liberties, Hearing on ECPA Reform and the Revolution in Location
Based Technologies and Services, 六月 24, 2010.

13 If the user is signed in, as are most Android users, then Google will learn which apps are being
used and how frequently, though not what information is being communicated (unless the apps
are Google apps).

14 See Amanda Koulousias, “Location, Location, Location,” Federal Trade Commission, 二月 11,
2015, https://www.ftc.gov/news-events/blogs/business-blog/2015/02/location-location-location.

15 参见https://www.torproject.org.
16 詹姆斯·鲍尔, Glenn Greenwald, and Bruce Schneier, “nsa and gchq Target Tor Network that

Protects Anonymity of Web Users,“ 守护者, 十月 4, 2014.

17 Export controls had effectively prevented the deployment of cryptography in domestic prod-
ucts. While the change in regulations did not permit export of cryptography in all products, 它
worked well enough to support the needs of the expanding Internet ecosystem. See Whit½eld
Dif½e and Susan Landau, “The Export of Cryptography in the 20th Century and the 21st,” 在
History of Information Security: A Comprehensive Handbook, 编辑. Karl De Leeuw and Jan Bergstra
(阿姆斯特丹: 爱思唯尔, 2007), 725–736.

18 See Nicole Perlroth and Scott Shane, “As F.B.I. Pursued Snowden, an E-Mail Service Stood

Firm,“ 纽约时报, 十月 2, 2013.

19 Google Support, Chat Help, “Chatting Off the Record,” https://support.google.com/chat/

answer/29291?hl=en (三月访问 29, 2015).

20 Whit½eld Dif½e, Paul van Oorschot, and Michael Wiener, “Authentication and Authenticated

Key Exchanges,” Designs, Codes, and Cryptography 2 (2) (六月 1992): 107–125.

21 Surveillance Self-Defense, “How to: Use otr for Mac,” and “How to: Use otr for Windows,”
Electronic Frontier Foundation, https://ssd.eff.org/en/index (三月访问 30, 2015).
22 Levison had previously complied with court orders for targeted access. His objection to the fbi
request was that the agency sought the encryption key for his ssl certi½cate, which would
have compromised the privacy of all Lavabit users. See Perlroth and Shane, ”As F.B.I. Pursued
Snowden, an E-Mail Service Stood Firm.”

23 Spiegel Staff, “Inside tao: Documents Reveal nsa Top Hacking Unit,” Spiegel Online International,

十二月 29, 2013.

24 在这种情况下, to determine ip addresses; but the method can also be used to ex½ltrate data, 在-
cluding encryption keys. See Steve Bellovin, Matt Blaze, Sandy Clark, and Susan Landau, “Going
Bright: Wiretapping without Weakening Communications Infrastructure,” IEEE Security and
Privacy 11 (1) (一月二月 2013): 62–72; and Steve Bellovin, Matt Blaze, Sandy Clark,
and Susan Landau, “Lawful Hacking: Using Existing Vulnerabilities for Wiretapping on the In-
ternet,” Northwestern Journal of Technology and Intellectual Property 12 (1) (2014).

25 See Bellovin et al., “Going Bright.”
26 Karl Koscher, Alexei Czeskis, Franziska Roesner, 等人。, “Experimental Security Analysis of a
Modern Automobile,” in Proceedings of IEEE Symposium on Security and Privacy (Oakland) 2010,

苏珊
Landau

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

145 (1) 冬天 2016

选择:
Privacy &
Surveillance
in a Once
& 未来
互联网

编辑. David Evans and Giovanni Vigna (华盛顿, 华盛顿特区: ieee Computer Society, 2010), 447–
462.

27 See President’s Council of Advisors on Science and Technology, Big Data and Privacy: A Techno-
logical Perspective (华盛顿, 华盛顿特区: Executive Of½ce of the President, 可能 2014), https://万维网
.whitehouse.gov/sites/default/½les/microsites/ostp/PCAST/pcast_big_data_and_privacy_-_may
_2014.pdf.

28 Message decryption led to the downfall of Mary, Queen of Scots, in the sixteenth century; 看
The National Archives of the United Kingdom, Codes and Ciphers, “Mary’s Ciphers,” http://
www.nationalarchives.gov.uk/spies/ciphers/mary/ma1.htm.

29 The lack of connection to communication networks was one hint that bin Laden was in the villa
in Abbottabad; see Mark Mazzeti, Helen Cooper, and Peter Baker, “Behind the Hunt for Bin
Laden,“ 纽约时报, 可能 2, 2011.

我

D
哦
w
n
哦
A
d
e
d

F
r
哦
米
H

t
t

:
/
/

d
我
r
e
C
t
.

米

我
t
.

e
d
你
d
A
e
d
A
r
t
我
C
e
–
p
d

我

F
/

1
4
5
1
5
4
1
8
3
0
7
0
3
d
A
e
d
_
A
_
0
0
3
6
5
p
d

乙
y
G
你
e
s
t

哦
n
0
9
S
e
p
e
米
乙
e
r
2
0
2
3

代达罗斯, 美国艺术学院学报 & 科学
下载pdf