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Quantum CryptographyAnkit Shukla, Deepak Kumar(3rd year)

Computer Science Department,ABES Engg. College,

(Gautam Buddh Technical University)

[email protected]

[email protected]

Abstract

Threats and attacks to information systems security on

digital

network environment are growing rapidly, putting pressure

on

businesses to protect their tangible and intangible assets.Itis reported that 75% of surveyed organizations have

confronted different network security attacks. For thatreason,cryptography is a vital of todays computer and

communications networks, protecting everything frombusiness e-mail to bank transactions and internet shopping.

But the scholars argue that, the current encryption

algorithms based on mathematical model introduce

potential security holes related to the key refresh rate and

key expansion ratio, the most crucial parameters in the

security of any cryptographic techniques.These

cryptographic techniques are widely used but are not proved

to be completely secure, representing one of the main threatsto modern network communication systems.For past decade

efforts have been made to establish new foundation for

cryptography science in the computer communicationsnetworks. One of these efforts has led to the development of

quantum cryptography technology, whose security relies onthe laws of quantum mechanics.

I. INTRODUCTION

Network security consists of the provisions and policies

adopted by a network administrator to prevent and

monitor unauthorized access, misuse, modification, or

denial of a computer network and network-accessible

resources. Network security involves the authorization of

access to data in a network, which is controlled by thenetwork administrator. Users choose or are assigned an ID andpassword or other authenticating information that allows them

access to information and programs within their authority.Network security covers a variety of computer networks, both

public and private, that are used in everyday jobs conductingtransactions and communications among businesses,

government agencies and individuals.Networks can be private,such as within a company, and others which might be open to

public access. Network security is involved in organizations,enterprises, and other types of institutions. It does as its title

explains: It secures the network, as well as protecting andoverseeing operations being done.

Current encryption algorithms based on mathematical

model introduce potential security holes related to the key

refresh rate and key expansion ratio. That is the sole reason

why modern cryptographic techniques like Quantum

Cryptography is introduced.

II. DETERMINETHEFACTORSINVOLVEDINASECURENETWORKSTRATEGY

Define & enforce policies and procedures

Analysis of both internal and external threats

Reduce risk across perimeter security, the Internet,

intranets, Extranet, and LANs ,Human factors

Risk Assessment (Know your weakness)

Limit access

Achieve security through continuous process

Remember physical security

III. DETERMINETHEFACTORSINVOLVEDINASECURENETWORKSTRATEGY

Access Control (Only legitimate traffic) Firewall Management process to security issues Cryptography (Encryption/Decryption) IDS (Intrusion Detection Systems)

IV. UNDERSTAND THE BASICS OF ALGORITHMSAND HOW THEY ARE USED

IN MODERN CRYPTOGRAPHY

Mathematical functions that work in tandem with a

key

Same plaintext data encrypts into different cipher-

text with different keys

Security of data relies on two factors:


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Strength of the algorithm

Secrecy of the key

Fig. 1 A graph between computing time of encryption algorithm and key

length.

V. VULNERABILITIES/WEAKNESS TO THE

MODERN/CLASSICAL CRYPTOGRAPHY

There are three main problems with encryption schemes.

1) The first is key distribution, which must be in itself,

2) The second is key management, where the number ofkeys required in a system with a large number of principals

does not scale well.

3) Thirdly as computing power increases, and new

classical computational techniques are developed, the lengthof time that a message can be considered secure will decrease,

and numerical keys will no longer be able to provideacceptable levels of secure communications.

4) Vulnerable to the progress in computation

(supercomputers) and algorithms.

5) Vulnerable to future quantum c.omputation protocols.For example:

5.1) Shors Algorithm (Peter Shor): Factoring allows

for factoring large numbers on a quantum computer in

polynomial time, theoretically breaking RSA encryption.

5.2) While any practical application on Shors

algorithm may be decade away, but an experimental proof-of-

concept of Shors algorithm has successfully been achieved .

VI. UNDERSTANDING OF THE QUANTUM

CRYPTOGRAPHY

Quantum cryptography concept developed byCharles H. Bennett and Gilles Brassard in 1984

(BB84) as part of research study between physics and

information at IBM lab.

The quantum system is based on the distribution ofsingle particles or photons, and the value of a

classical bit encodes by the polarization of a photon .

In fact, the quantum cryptography relies on two

important elements of quantum mechanics-the

Heisenberg Uncertainty principle and the principleof photon polarization.

The Heisenberg Uncertainty principle states that, it is

not possible to measure the quantum state of anysystem without distributing that system.This means,

the polarization of a photon or light particle can only

be known at the point when it is measured.

Secondly, the photon polarization principle explains

how light photons can be polarized in a specificdirection.

In addition, an eavesdropper can not copy unknown

qubits i.e. unknown quantum states, due to no-

cloning theorem which was first presented by

Wootters and Zurek in 1982.

VII. PHOTONS POLARIZATION

A photon has a property called polarization, which is theplane in which the electric field oscillates.We can use photons

of different polarizations to represent quantum states.

Each of these photons is in a state denoted by one of

the four following symbols: , |, /, \

The first two photon states are emitted by a polarizerwhich is set with a rectilinear orientation and the

other two states are emitted by a polarizer which is

set with a diagonal orientation. The polarization basis is the mapping we decide to

use for a particular state.

Rectilinear Diagonal

= 0 => state 0 = 45 => state 0

= 90 => state 1 = 135=> state 1


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VIII. QKD PROTOCOLS

A security protocol is a special protocol designed to

ensure security properties are met duringcommunications.

There are three main security protocols for QKD:BB84, B92, and Entanglement-Based QKD.

IX. BB84 PROTOCOL

BB84 was the first security protocol implementing

Quantum Key Distribution.It uses the idea of photonpolarization.

The key consists of bits that will be transmitted asphotons. Each bit is encoded with a random

polarization basis!

X. BB84 PROTOCOL WITH NO EVE (NO

EAVESDROPPING)

Sender's side:

Alice is going to send Bob a random key.She begins with transmitting a random sequence of bits.

Bits are encoded with a random basis

Receiver's side: Bob receives the photons and must decode them

using a random basis.

Some of his measurements are correct.

Testing bits

Alice and Bob talk on the telephone:

Alice chooses a subset of the bits (the test bits)

and reveals which basis she used to encode

them to Bob.

Bob tells Alice which basis he used to decodethe same bits.

Where the same basis was used, Alice and Bobagree on the bits.

XI. BB84 PROTOCOL WITH EVE (IN THE PRESENCE OF

EAVESDROPPING)

If an eavesdropper Eve tries to tap the channel, this

willautomatically show up in Bobs measurements.

In those cases where Alice and Bob have used thesame

basis, Bob is likely to obtain an incorrect measurement(Error Rate).

Eves measurements are bound to affect the states ofthe

photons.

As Eve intercepts Alices photons, she has to

measure them with a random basis and send newphotons to Bob.

The photon states cannot be cloned (no-cloning

theorem which was first presented by Wootters and

Zurek in 1982.

Eves presence is always detected: measuring aquantum system irreparably alters its state (The

Heisenberg Uncertainty principle) .


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XII. TECHNICAL CHALLENGES OF QKD AND FUTURE

DIRECTION

One of the challenges for the researchers, is distancelimitation.

Currently, quantum key distribution distances arelimited to tens of kilometers because of optical

amplification destroys the qubit state.

Also to develop optical device capable of generating,

detecting and guiding single photons; devices that areaffordable within a commercial environment .

Another issue is the lack of a security certificationprocess or standard for the equipment .

Also users need reassurance not only that QKD is

theoretically sound, but also that it has been securelyimplemented by the vendors.

XIII. CONCLUSIONS

Realization of practical quantum informationtechnologies can not be accomplished without

involvement of the network research community.

The advances in computer processing power and the

threat of limitation for todays cryptography systemswill remain a driving force in the continued research

and development of quantum cryptography.

The technology has the potential to make a valuablecontribution to the network security among

government, businesses, and academic environment.

ACKNOWLEDGMENT

REFERENCES

[1] MagiQ Technologies, Inc. (USA) www.magiqtech.com[2] IdQuantique (Switzerland) www.idquantique.com

[3] NEC (Japan) www.nec.com[4] Research Groups working on QKD at IBM and Toshiba

(USA, europe)

[5] http://www.research.ibm.com/physicsofinfo/index.htm#

[6] http://www.toshiba-europe.com/research/crl/QIG/

[7] Japan Research Group

[8] http://www.aist.go.jp/aist_e/event/ev2007/ev20071001/ev20071001.html

[9] NIST Research Group

[10] http://www.nist.gov/public_affairs/quantum/quantum_info_index.html

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