On Privacy Protection in the Internet Surveillance Era

Dijana Vukovic

1,2

, Danilo Gligoroski

and Zoran Djuric

Department of Telematics, NTNU, O.S. Bragstads plass 2B, Trondheim, Norway

Department of Computer Science and Informatics, Faculty of Electrical Engineering,

Patre 5, Banja Luka, Bosnia and Herzegovina

Keywords: Internet Surveillance, Diffie-Hellman Key Exchange, Privacy, Chat Communication.

Abstract: Snowden's whistleblower from the last year made people more aware of the fact that we are living in the

Internet surveillance era. Privacy of Internet communication has been disrupted. In this paper, application

for privacy protection in chat communication, named CryptoCloak, is presented. CryptoCloak provides

privacy protection for chat communication. Encrypted communication is masked with dynamic cheap chat

conversation. Communication made this way is not point of interest for mass surveillance spying engines.

For implementation of the CryptoCloak, Facebook Messenger API is used. Diffie-Hellman key exchange is

done in clandestine manner - instead of sending uniform sequence of numbers, sentences are sent. Current

version provides encryption/decryption mechanism for the chat communication using strong symmetric

algorithm AES in CBC mode. 256 bits of Diffie-Hellman exchanged key are used for AES-CBC.

1 INTRODUCTION

The whistleblower by Edward Snowden about

Internet surveillance in the past year had huge

influence on everyone: ordinary users, researchers,

companies. Ordinary users started to care more

about their privacy on the Internet (Hattem, 2014)

researchers in the field of information security

focused their research on protection against Internet

surveillance, while companies started to care more

about privacy and security of their users (Ashford,

2014). The Guardian published and keeps on

publishing many articles related to this topic. The

whole timeline of information discovered about

NSA (US National Security Agency) surveillance

can be found here (Gidda, 2013). Similar violation

of users’ privacy was done by GCHQ (UK

Government Communications Headquarters)

Information about PRISM and Tempora programs

used by US and UK intelligence agencies to collect

private data were the part of Snowden’s

whistleblower. PRISM is a tool used by the NSA to

collect private electronic data belonging to the users

of the major Internet companies (Google, Facebook,

etc). Tempora program provides GCHQ a direct

access to large amounts of the global Internet data

over UK-based fibre optic cables which include

transatlantic cables that carry Internet traffic

between the US and Europe (Harding, 2014).

According to (Khudayer et.al., 2014) NSA collects

content, metadata, and upstream data, and shares it

with GCHQ, Central Intelligence Agency, and

Department of Justice FBI. Data are collected from

different sources (Apple, Google, Microsoft, etc.)

and collection is justified by Patriot Act (Section

215) and FISA Amendments Act (Section 702).

Surveillance can be defined as “close observation

of a person or group, especially one under

suspicion” (Martin, 2010). Many terroristic activities

during past years lead to Internet surveillance. Law

enforcement agencies needed the ability to conduct

electronic surveillance to prevent crime, terrorism,

or any kind of malicious activities exploiting the

Internet. Many people have opposed surveillance

because it can be considered as an invasion of

privacy (as with hidden video cameras) or a tool of

social control (as in monitoring workers).

Surveillance can be justified in some cases, as a

cracking down a crime, or increasing efficiency of

service systems, but it can also be a big threat to

privacy. Privacy can simply be defined as “the right

to be left alone”. Privacy is the right of each

individual, and it should not be threatened if it is not

harmful to the others.

On February 11, 2014 “The Day We Fight Back”

was organized by EFF (Electronic Frontier

Foundation) against mass surveillance (Kamdar,

261

Vukovic D., Gligoroski D. and Djuric Z..

On Privacy Protection in the Internet Surveillance Era.

DOI: 10.5220/0005043002610266

In Proceedings of the 11th International Conference on Security and Cryptography (SECRYPT-2014), pages 261-266

ISBN: 978-989-758-045-1

 2014 SCITEPRESS (Science and Technology Publications, Lda.)

2014). Over 850,000 people took part in it and

different events were held on five continents - from

Ireland to India, California to South Africa. A

campaign calling for a “free, open and truly global

Internet” was launched by Tim Berners-Lee to mark

the 25th anniversary of World Wide Web invention.

It becomes evident that Internet surveillance era has

brought a huge increase of the violation of privacy.

As a response to the violation of privacy, Bruce

Schneier wrote the article "The US government has

betrayed the Internet. We need to take it back."

(Schneier, 2013). The main idea of this article was

that the engineering community need to bring back

Internet as it used to be to the people - (Schneier,

2013) "This is not the Internet the world needs, or

the Internet its creators envisioned. We need to take

it back. And by we, I mean the engineering

community. Yes, this is primarily a political

problem, a policy matter that requires political

intervention. But this is also an engineering

problem, and there are several things engineers can

– and should – do." Guided by this idea, we started

the CryptoCloak project.

The basic idea of the CryptoCloak can be

described as the following: we will use the solid and

secure algorithms that have been proved as secure,

but do the encryption in a clandestine manner. The

automatic filtering rules of the spying agencies will

notice just a cheap chat conversations, while the real

encrypted information will be incorporated deeply in

that cheap chat. The cheap chat will be our cloak to

encrypted information.

According to (Regalado, 2013), computer

scientists are involved in enabling intrusion on

individual privacy and this lead to breaking the code

of ethics (ACM Council, 1992). This project will be

our attempt to follow the basic idea of (Schneier,

2013) and to enable use of the code of ethics in the

right way – to contribute to society and human well-

being without doing harm to others, and with

respecting the privacy of others.

Section 2 gives an overview of existing solution

related to the privacy protection in Internet

communication. In Section 3 the idea and

implementation of the CryptoCloak project are

described, with an example of its usage. Section 4

gives an overview of further work, and the paper is

concluded in Section 5.

2 RELATED WORK

To the best of our knowledge, there are no chat

applications that provide private communication the

way the CryptoCloak does. Most of related solutions

use steganography - the act of concealing data in

plain sight. Steganography application in network

provides a possibility to carry on hidden information

over Internet seemingly like innocent Internet traffic.

Authors in (Mazurczyk et.al., 2013) presented

results of their research in the field of network

steganography to show how the network

steganography can be used exploiting a common use

of the Internet. SkyDe program exploits silence

packets sent during the voice communication over

Skype to send hidden information. StegTorrent

program exploits the weakness of BitTorrent, that

BitTorrent user often shares a data file (or pieces of

the file) with many recipients at once. The third

presented research resulted with StegSuggest

steganography program targets the feature Google

Suggest, which lists the 10 most popular search

phrases given a string of letters the user has entered

in Google’s search box. Wireless Padding, or WiPad

method is related to Wi-Fi Networks weaknesses, on

networks that use the data-encoding technique

known as OFDM (orthogonal frequency-division

multiplexing).

Internet censorship by government becomes an

increasingly common practice worldwide. Between

Internet users and censors now the "arms race" is

started. For encrypted conversation over the Internet

a lot of applications can be found. The most known

one is Tor (Tor, 2014). It can be described as a

"network of virtual tunnels". Tor provides

protection from a common form of Internet

surveillance known as "traffic analysis" by

distributing transactions over several places on the

Internet. This idea is similar to twisty - hard to

follow route in order to throw of somebody who is

tailing you. As a camouflage proxy for Tor,

StegoTorus was developed. StegoTorus improves

the resilience of Tor to fingerprinting attacks and

delivers usable performance (Weinberg et.al., 2012).

Cryptocat (open source software) (CryptoCat,

2014) uses modern web technologies to provide easy

to use, accessible encrypted chat. It is developed as

plug-in for most popular web browsers. Chat

conversation is encrypted before sending — even the

Cryptocat network itself can't read it.

Spying engines do the traffic analysis in the

following way: (1) filter the content looking for

particular keywords, e.g. bomb, terrorism, etc.;

content will be analyzed to prevent potential

terroristic attacks or similar issues, (2) any encrypted

content will be stored for further analysis, (3)

noticing cheap chat conversations, e.g. "Hello!",

"How are you?" - will be ignored. To provide spying

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engines proof communication over the Internet, it

has to be similar to the cheap chat communication.

That can be used as a manner of masking previously

encrypted communication.

CryptoCloak does not use the steganography. It

does not embed the information in some other

existing information. It produces a fake real-time,

dynamic cheap chat and there it embeds the secret

information. Messages sent via CryptoCloak

application are not encrypted, as it is the case for

Cryptocat, and they will not be detected by spying

engines as suspicious.

3 THE CryptoCloak PROJECT

CryptoCloak communication between Alice and Bob

is represented in Figure 1. Diffie-Hellman key

exchange is done in the modified way - instead of

regular primes the sequence of sentences is going to

be sent. The first step is selecting the source of

sentences: URL (Uniform Resource Locator) or

database. URL has to be a link for the free online

available text document to provide the same source

of sentences for both communication sides (Alice

and Bob) for encryption and decryption. Currently,

the CryptoCloak uses the free e-books published

under the "Project Guttenberg" (Gutenberg, 2014).

Figure 1: The CryptoCloak.

There can be found over 40000 e-books from

different genre. When URL is selected as a source of

sentences, Alice chooses one e-book in textual

format from the "Project Guttenberg" official web

site and copies its URL , and sends this URL to Bob,

e.g. "Alice's Adventures in Wonderland" -

http://www.gutenberg.org/cache/epub/28885/pg2888

5.txt. On the both sides, using the same algorithm,

the chosen text document is transformed into the

map of pairs (index, sentence). Only different

sentences will come into consideration when

transformation algorithm is applied. Next step is

calculation of number n that fulfil the condition



2



, where sn is number of sentences in

the set after transformation. For "Alice's Adventures

in Wonderland" sn=962, which gives us n=9.

Using Diffie-Hellman key exchange algorithm, a

should be sent over the network from Alice's side. p

and g are public, and they are built in the

application. After calculation of a, a is transformed

into its binary value, then split into blocks of n bits.

For every block, decimal value is recalculated - it is

an index to get corresponding sentence from

generated map. Finally, instead of regular primes,

sequence of sentences is sent over the network. The

length of the parameter a is also sent as a sentence -

sentence is chosen from the map where index value

is equal to the length value. On the Bob's side

reverse algorithm is executed on the received

sequence of sentences and the actual values of sent

primes are shown to Bob. Bob calculates b, encrypts

it the same way as Alice did with a, and send it to

her. He generates his key using the b value. Alice

retrieves b, decrypts it and calculates the key. At the

end, both sides have the same key - b

mod p = a

mod p. When the database is selected as a source of

sentences, sentences will be read from the internal

database. Key exchange will be done in the same

way as it is previously described.

After successful Diffie-Hellman key exchange,

256 bits of the key will be used for AES-CBC

encryption. The message user (Alice) enters in the

CryptoCloak chat will be encrypted using AES-CBC

encryption, masked and sent after that in the same

way as the Diffie-Hellman parameters were in the

key exchange process. On the receiver side, received

sentences will be transformed to encrypted content,

and after that the decryption will be done. The

receiver (Bob) sees only the decrypted content.

3.1 Implementation of the Cryptocloak

CryptoCloak is Java GUI (Graphical User Interface)

chat application implemented using Java Swing API

(Application Programming Interface).

Implementation using Java programming language

provides hardware independence, as well as

operating system independence.

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Figure 2: The versions of the CryptoCloak.

In the first version of the CryptoCloak (Figure

2), all communication between Alice and Bob was

done over the Skype. In that purpose, Skype API

was used. At the end of 2013, Skype API got retired

(Callaham, 2013). In the second version of the

CryptoCloak, Facebook Messenger API is used.

The internal structure of the CryptoCloak chat

application is shown in Figure 3.

Figure 3: The CryptoCloak inner structure.

It consists of four modules:

 User interface – consists of classes that

represents GUI of the CryptoCloak

application,

 Communication – consists of classes for

sending/receiving chat messages,

 Data retrieval and manipulation –

consists of classes for preparing

appropriate set of sentences,

 Crypto algorithms – consists of

implementations for used cryptographic

algorithms.

To establish communication over the Internet for

instant messaging, XMPP (Extensible Messaging

and Presence Protocol) protocol is used. XMPP is a

protocol for streaming XML elements in order to

exchange messages and presence information in

close to real time. Additional Java library is used for

XMPP communication – Smack (Jive Software,

2014). Smack is an Open Source XMPP (Jabber)

client library for instant messaging and presence.

The entire XMPP communication is done over the

Facebook XMPP server (chat.facebook.com), and to

use the CryptoCloak a legitimate Facebook account

is needed. Module for communication, besides

XMPP part, has a part for sending and receiving

messages which lays on concurrency (Threads) –

two different threads for sending and receiving

messages are implemented (two per user), and it

supports multithreading Research of the average

typing speed from (Fort, 2014) is used as a reference

for making delay between sending sentences, to

make the impression that communication is not

automated. According to (Fort, 2014) average typing

speed of regular user is 41 words per minute. Before

sending sentence, number of words in it is

determined, and the approximated time for typing

the sentence is calculated. After receiving sentence,

some random sentence will be picked up from

sentences map and sent to the other side in the same

way.

As it is already described in Section 3,

CryptoCloak can use two sources of sentences for

cheap chat communication: online textual file, or

internal database. To eliminate dependency of

RDBMSs (Remote DataBase Management Server)

and avoid need of additional installation and

configuration on the user computer, a simple XML

file is used as data store. Currently, XML database is

filled with dialogues from English learning book

"Speak English like an American", and from online

school for practicing English conversation

(http://www.eslfast.com/robot/topics/smalltalk/small

talk.htm), and it contains 1438 sentences. Speed of

conversation is dependent on the size of the map.

The bigger map, the larger will be size of the block,

and it will decrease the number of sentences for

sending parameters a and b.

Data retrieval and manipulation module contains

of XML and Utilities parts. XML part does reading

and writing XML file using standard Java API. At

the current version, CryptoCloak uses two crypto

algorithms: Diffie-Hellman and AES-CBS.

Additional cryptography library is used for the

implementation of this module – Bouncy Castle

(Bouncy Castle, 2014). A part for the Diffie-

Hellman calculations uses SecureRandom Java class

for generating needed random numbers, because

commonly used Random class is not recommended

for use in cryptographic implementations.

Parameters p and g for Diffie-Hellman can be

read/changed from/in the properties file built in with

application. The important fact is that both sides,

Bob and Alice, have to agree on the source of

sentences, and p-g parameters (if they are entered

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manually, they have to be the same), otherwise

Diffie-Hellman key exchange will not be successful.

In the Utilities part different Java classes with

methods for reading properties file, parsing textual

file to get different sentences, conversing primes to

sentences array etc., can be found.

3.2 Usage of the CryptoCloak

CryptoCloak is a simple GUI application. After

running application, login window appears (Figure

4). To start using CryptoCloak chat, login has to be

done with Facebook login credentials – username

and password.

Figure 4: The CryptoCloak login window.

For testing purpose, two new Facebook accounts

were created. In the testing phase, application was

installed on one PC with Intel(R) Core(TM) i7-

3632QM CPU @ 2.20GHz with 8 GB of RAM, and

on the Virtual machine on that PC. Host operating

system was Windows 7 Home Premium with

Service Pack 1, and virtual operating system was

Ubuntu 12.04. 1GB of host RAM was allocated for

virtual operating system.

When the parameter p, needed for Diffie-

Hellman key exchange, is sending over the

CryptoCloak chat application, it will be masked with

the array of sentences as it is described in Section 3.

If we have p set in the properties file with a value

"16787426697985151626517779571624089983022

120666271652290333300379825527897398425284

401806118280365937667016198298392735400958

960612093648967418648279257372006530723054

224947450011008829708513268214041078156030

940307913839243746827886992741401150053658

374219960553436925655394188565774454701526

7866266696066601", array of 103 sentences will be

sent. In Figure 5, one part of the sentences sending

in shown. In Figure 6 the result of successful key

exchange is shown.

Figure 5: Sentences sending.

(a)

(b)

Figure 6: (a) Alice; (b) Bob.

4 FURTHER WORK

Exchange time for a and b parameters is quite long

(in total around 30 minutes). Considering the fact

that Java has an e-mail API, we can speed up a

process of parameters exchange by sending them as

an e-mail message. Using the same algorithm

described in Section 3 parameters will be converted

into array of sentences, and, instead of sending

sentences via chat communication, they will be sent

using legitimate e-mail account. CryptoCloak will be

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modified in a way that user can send/receive e-mail

message over/from different accounts. It means that,

instead of sending parameters a and b over chat

communication, they, as sentences array, can be split

and send over a few different e-mail accounts, and

merged from these accounts on receiver side. When

the particular parameter is received, it will be

transformed into its real value, and the key will be

calculated. The same process will be executed on the

both sides, Bob’s and Alice’s, and after the

successful Diffie-Hellman key exchange, they can

start AES-CBC encrypted communication in the

way described in Section 3. If we split

communication in a way that the key exchange will

be done over e-mail and AES-CBC communication

over XMPP, it will be efficient and harder to follow.

It will be similar to the technique the Tor uses –

twisty (route which is hard to follow).

Facebook announced shutting-down of Facebook

messenger. The question mark in Figure 2 stands for

the new way of communication in the future that

will be used instead of current Facebook Messenger

API. Considering the fact that XMPP is reliable

protocol, "?" can be replaced with any free available

XMPP server.

5 CONCLUSIONS

Privacy of individuals should not be threatened in

any case, but Internet surveillance era represents a

huge threat to it. The CryptoCloak project has the

aim – protection against surveillance in the chat

communication. Diffie-Hellman key exchange over

the network, without sending sequence of bytes, will

not be detected by traffic analysis tools (spying

engines). After successful key exchange, AES is

used for encryption/decryption of chat

communication, and the CryptoCloak masks

communication providing dynamic cheap chat

conversation. The CryptoCloak is now in the testing

and bugs fixing phase, and some additional features

(e.g. selection of conversation topic, different

languages support) will be added in the future.

ACKNOWLEDGEMENTS

Dijana Vukovic, as a PhD student in the field of

information security, is supported by the COINS

Research School of Computer and Information

Security.

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