Ppt Quantum Cryptography

8/6/2019 Ppt Quantum Cryptography

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QUANTAMCRYPTOGRAPHY

-SECRECY ENSURED


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TABLE OF CONTENT

TECHNOLOGYKEY DISTRIBUTUION

CLASSICAL

CRYPTOGRAPHY

QUANTAM

CRYPTOGRAPHY

WORKING

INTRODUCTION

SECURITY

CONCLUSION

ADVANTAGES LIMITATIONS


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INTRODUCTION

The recent application of theprinciples of quantum mechanics tocryptography has led to aremarkable new dimension in secretcommunication.

Quantum cryptography is an effortto allow two users of a common

communication channel to create abody of shared and secretinformation.


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CRYPTOGRAPHY

The whole point of cryptography is

to keep information out of the hands

of anyone but its intended recipient.

Even if the message gets intercepted,

the meaning wont be apparent to the

intercepted unless the interceptoris able to decipher it.


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Principle of Cryptography.


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A PRACTICAL EXAMPLE -

Alice wants to send a message to

Bob, without an eavesdropper Eve

intercepting the message.


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TYPE OF CRYPTOGRAPHY

CRYPTOGRAPHY

Classical Quantum


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THE CLASSICAL CRYPTOGRAPHY

Encryption algorithm and related

key are kept secret.

Breaking the system is hard due to

large numbers of possible keys.

For example: for a key 128 bits

longthere are keys to

check.

38128102 }


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THE QUANTUM CRYPTOGRAPHY

An important and unique property of

quantum cryptography is the ability

of the two communicating users to

detect the presence of any thirdparty trying to gain knowledge of

the key.

Quantum technology promises torevolutionize secure communication

at an even more fundamental level.


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THE QUANTUM CRYPTOGRAPHY

Quantum Cryptography ensuring themost secure transmission of the secretinformation works on the principle of Quantum Mechanics.

Transmission is carried out at the bitlevel with the help of various types ofalignment of the photons.

It also solves the problem of keydistribution arising in the ClassicalCryptography.


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WORKING


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QUANTUM KEY DISTRIBUTION

Auser can suggest a key by sendinga series of photons with randompolarizations. This sequence canthen be used to generate a sequence

of numbers. The process is known asquantum key distribution.

Main Features: Key distribution distance: up to 60

km

Key distribution rate: up to 1000

bits/s


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QUANTUM CRYPTOGRAPHY TECHNOLOGY

Photon Source.

Photon Detector.

Communication channel.


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PHOTON SOURCE

Photon Gun.

Light - emitting p-n junction.

Single ion.


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PHOTON DETECTOR

Avalanche photodiodes.

Germanium detectors.

Silicon.

Photo multiplier.


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COMMUNICATION CHANNEL

Fiber optical communication link.

Free space laser communication.


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SECURITY OF QKD

Quantum cryptography obtains its

fundamental security from the fact

that each qubit of information is

carried by a single photon, and thateach photon will be altered as soon

as it is read once.

This makes impossible to intercept

message without being detected.


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EFFECT OF NOISE

The presence of noise can impact

detecting attacks.

Eavesdropper and noise on the

quantum channel are

indistinguishable.

Detecting eavesdropper in the

presence of noise is hard.


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APPLICATION

E-mail messages.

Telephone calls. Financial Transactions.


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ADVANTAGES

The most important contribution of

quantum cryptography is a mechanism

for detecting eavesdropping.

Quantum key distribution enables

encrypted communications on demand,

because it allows key generation at

transmission time over an unsecured

optical communications link.


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LIMITATIONS

We have to use pure fiber optic end-to-

end network and boosters are needed at

some distance, so it is expensive.

It will also be critical to authenticate

the identity of the recipients.

It is also not clear how to modify the

scheme in order to deal with noisy

quantum transmissions.

It is hard to transmit a photon, entangled

over great distances. Photon detectors

aren't particularly reliable.


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CONCLUSION

Currently it works only over shortdistances, but there are situations in

which even short-distance transmission is

useful.Also, with sufficient technical

improvements, it might be possible in the

future to implement quantumcryptography over long distances.

The devices for implementing such

methods exist and the performance of

demonstration systems is beingcontinuously improved. Within the next

few years, such systems could startencrypting some of the most valuable

secrets of government and industry.


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Ppt Quantum Cryptography

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