8/12/2019 Main Project Report 2

1/5

ABSTRACT

Anonymizing networks such as Tor allow users to access Internet services

privately by using a series of routers to hide the clients IP address from the server.

The success of such networks, however, has been limited by users employing this

anonymity for abusive purposes such as defacing popular websites. ebsite

administrators routinely rely on IP!address blocking for disabling access to

misbehaving users, but blocking IP addresses is not practical if the abuser routes

through an anonymizing network. As a result, administrators block all known e"it

nodes of anonymizing networks, denying anonymous access to misbehaving and

behaving users alike. To address this problem, we present #ymble, a system in which

servers can $blacklist% misbehaving users, thereby blocking users without

compromising their anonymity. &ur system is thus agnostic to different servers

definitions of misbehavior ' servers can blacklist users for whatever reason, and the

privacy of blacklisted users is maintained.

PROJECT PURPOSE

Anonymizing networks such as Tor allow users to access Internet servicesprivately by using a series of routers to hide the clients IP address from the server.

The success of such networks, however, has been limited by users employing this

anonymity for abusive purposes such as defacing popular eb sites. eb site

administrators routinely rely on IP!address blocking for disabling access to

misbehaving users, but blocking IP addresses is not practical if the abuser routes

through an anonymizing network.

i

8/12/2019 Main Project Report 2

2/5

PROJECT SCOPE

eb site administrators cannot blacklist individual malicious users IP

addresses, they

blacklist the entire anonymizing network. (uch measures eliminate malicious activity

through anonymizing networks at the cost of denying anonymous access to behaving

users. In #ymble, users ac)uire an ordered collection of nymbles, a special type of

pseudonym, to connect toebsites. ithout additional information, these nymbles are

computationally hard to link,* and hence, using the stream of nymbles simulates

anonymous access to services.

eb sites, however, can blacklist users by obtaining a seed for a particular nymble,

allowing them to link future nymbles from the same user'those used before the

complaint remain unlinkable. (ervers can therefore blacklist anonymous users without

knowledge of their IP addresses while allowing behaving users to connect

anonymously.

PRODUCT FEATURES

e have proposed and built a comprehensive credential system called #ymble,

which can be used to add a layer of accountability to any publicly known anonymizing

network. (ervers can blacklist misbehaving users while maintaining their privacy, and

we show how these properties can be attained in a way that is practical, efficient, and

sensitive to the needs of both users and services.

ii

8/12/2019 Main Project Report 2

3/5

LIST OF THE TABLE

SERIAL NO TABLE NO TABLE NAME PAGE NO

1 3.3.1 ADDRESS 26

2 3.3.2 LOGIN 26

3 3.3.3 RESOURCE 26

4 3.3.4 SERVER 26

iii

8/12/2019 Main Project Report 2

4/5

LIST OF FIGURES

SERIAL NO FIGURE NO FIGURE NAME PAGE NO1 2.2.1 overve! o" #$e

%&%#e'

6

2 2.2.3 (r)$#e)#*re o" #$e

%&%#e' +e%,-

3 3.1.1 D"+ /eve/ 0 20

4 3.1.2 D"+ /eve/ 1 22

3.2.4 C"+ 2

6 .1 N&'/e %erver 6

.2 N&'/e %erver

(*#$e-#)(#o-

6

.3 N&'/e $o'e

(,e

65

5 .4 N'/e ve! 0

10 . U%er ve! 1

11 .6 A++-, (++re%% 2

12 . B/o)-,

(++re%%

3

13 . P%e*+o '(-(,er 4

14 .5 F/e ())e%%

LIST OF ABBREVIATION

iv

8/12/2019 Main Project Report 2

5/5

+fd +ata flow diagram

-fd -ontrol flow diagram

Tor The onion router

/0 erifier!local revocation&+1- 2icrosoft &pen +atabase -onnectivity

3+1- 3ava +atabase -onnectivity

v