1. QUANTUM CRYPTOGRAPHY
BY
KAMAL DIWAKAR R(10131A1265)
Department of INFORMATION TECHNOLOGY
GAYATRI VIDYA PARSHID COLLEGE OF ENGINEERING(A)
MADHURUWADA,VISAKHAPATNAM

2. Table of Contents
.
1 Introduction
a) What is Cryptography?
b)What is Quantum Cryptography?
.
2 Why is the need for Quantum Cryptography?
Quantum Key Distribution
3.What problem does QKD Solve?
4.Is it complex to deploy QKD?
5.Types of Quantum cryptography
a)POSITION-based Quantum Cryptography
b)POST-Quantum Cryptography
6.Implementing Quantum Cryptography
7.Conclusion

3. 1.INTODUCTION
Quantum Cryptography was intoduced by two scientists "Charles Bennett" and "Gills Brassard" in 1991 based on
"conjugate coding" concepts.
What is Cryptography?
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
The art of protecting information by transforming it (encrypting it) into an unreadable format, called cipher text.
Only those who possess a secret key can decipher (or decrypt) the message into plain text.
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Cryptography systems can be broadly classified into symmetric-key systems that use a single key that both the sender and
recipient have, and public-key systems that use two keys, a public key known to everyone and a private key that only the
recipient of messages uses.
What is Quantum Cryptography?
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Quantum cryptography is an emerging technology in which two parties can secure network communications by applying the
phenomena of quantum physics.
The security of the transmissions is based on the inviolability of the laws of quantum mechanics.
Quantum cryptography relies on two important elements of quantum mechanics:
1) Based on "Heisenberg Uncertainty Principle" which states that it is not possible to measure the quantum state of any
system without distributing the system.
2)Based on "Photon Polarization" which states that eavesdrop cannot copy the quantum states.

4. 2.Why is the need for Quantum Cryptography?
•
•
•
Establishing a secret key with conventional communications is not possible.
Secure key distribution is possible with "Quantum Communications".
These Quantum Communications for secure key is done through "Quantum Key Distribution(QKD)" mechanism.
Quantum Key Distribution(QKD)
In this procedure the key is distributed over the quantum channel and not the encrypted message.
We need two channels between the sender A and the receiver B.
One channel for transmitting of encrypted message and another channel for key distribution called "quantum channel". Hence
the name, QUANTUM KEY DISTRIBUTION.
A
E
(eavesdrop)
Public Channel(telephone)
KEY
Quantum State Generator
t xet n al p
i
plain text
Encryption Algorithm
B
Decryption Algorithm
YE K
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Quantum Channel(OFC)
Quantum State Detector

5. 3.What Problem does QKD solve?
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•
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Quantum Key Distribution is a technology that allows transmission of a sequence of random bits across an optical network
and also verifies if this sequence was intercepted or not. This verification is based on the laws of quantum physics.
QKD is combined with conventional key distribution techniques (dual key agreement) to produce a key that is as secure as the
strongest of the two original keys.
QKD provides long-term data transmission secrecy, which is not vulnerable to technological progress. On the contrary,
classical cryptography provides secrecy only for a limited period of time.
4.Is it complex to deploy QKD?
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•
QKD is not complex to deploy. It has reached a level of maturity such that it only takes a typical network engineer a few
minutes to install a QKD system.
It can be managed using standard network administration tools.
5.Types Of Quantum Cryptography
•
POSITION-based Quantum Cryptography: The goal of position-based quantum cryptography is to use the
geographical location of a receiver as its (only) credential.
For example, one wants to send a message to a receiver at a specified position with the guarantee that it can only be read if the
receiving party is located at that particular position.
•
POST-Quantum Cryptography: it is important to study cryptographic schemes that are allegedly secure even against
adversaries with access to a quantum computer.The study of such schemes is often referred to as post-quantum cryptography.

6. 6.Implementing Quantum Cryptography
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DARPA is the quantum network developed by Boston and Harvard for America Airforce.It is the world's first end-to-end
network security via high -speed quantum distribution key.
The DARPA security model is the cryptographic virtual private network.

7. 7. Conclusion
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Quantum Cryptography is alternative solution for secure computer network communication.Instead of using general
encryption and decryption technique, quantum cryptography can verify that key is transmitted without interception from
eavesdrop
Quantum Cryptography could be the first application of quantum mechanics at the single quanta level.
Experiments have demonstrated that keys can be exchanged over distances of a few tens of kilometers at rates at least of the
order of a thousand bits per second.
Present quantum cryptography is still very limited in distance.

8. THANK YOU