quantum cryptography

VIGNAN’S INSTITUTE OF
MANAGEMENT AND TECHNOLOGY
FOR WOMEN
KONDAPUR(V),GHATKESAR(M),RANGAREDDY(DIST.)
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
ENGINEERING

INTRODUCTION
What is Cryptography?
 Cryptography is the art of devising codes and ciphers.
 Crypto analysis is the art of breaking them.
 Cryptology is the combination of the two i. e Cryptography
and Crypto analysis

INTRODUCTION
What is Quantum Cryptography?
 Quantum Cryptography is an effort to allow two users of a
common communication channel to create a body of
shared and secret information.
 This information, which generally takes the form of a
random string of bits, can then be used as a conventional
secret key for secure communication.

INTRODUCTION
What is Quantum Cryptography? Contd.
The Heisenberg Uncertainty principle, and quantum
entanglement can be exploited in as a system of secure
communication often referred to as “Quantum
Cryptography”.

INTRODUCTION
Quantum Entanglement:
Quantum entanglement is a physical phenomenon that
occurs when pairs or groups of particles are generated or
interact in ways such that the quantum state of each
particle cannot be described independently of the others,
even when the particles are separated by a large distance—
instead, a quantum state must be described for the system
as a whole.

CRYPTOGRAPHY
κρυπτόσ (kryptós)
“hidden”
+
γράφω (grápho)
“write”
=
Hidden Writing

HISTORY
4000 years ago, they used the concept of
SUBSTITUTION CIPHER with key for securing the
data.

 Since 1970: PUBLIC KEY CRYPTOGRAPHY, exchange
of secret messages with a person who you never met
before

 Now the present generation is using QUANTUM
CRYPTOGRAPHY for securing the information
without encrypting.
So, what is quantum cryptography??

QUANTUM CRYPTOGRAPHY
 Although the field of cryptography is ancient, but it is
not static. Quantum cryptography is a relatively new
concept in cryptography.
 Basically quantum cryptography is combination of
OTP and QKD.
 Quantum cryptography is based on two important
principles –
 Polarization of light.
 Heisenberg’s uncertainty principle

RSA
 The most widely used PKC is the RSA (Rivest –
shamir-Adleman) algorithm based on the
difficulty of factoring a product of two large
primes.
 Easy Problem Hard Problem
qpn  Given n
compute p and q.

QUANTUM KEY DISTRIBUTION
Quantum key distribution (QKD) uses quantum
mechanics to guarantee secure communication.
Quantum Key Distribution tell us all attempts of
eavesdropping.
Quantum key distribution is only used to produce and
distribute a key, not to transmit any message data
It enables two parties to produce a shared random bit
string known only to them, which can be used as a
key for encryption and decryption

OTP (ONE TIME PAD)
 One-time pad (OTP) is an encryption technique that
cannot be cracked if used correctly.
 The key used in a one-time pad is called a secret key

ADVANTAGES
 Virtually un-hackable.
 Simple to use.
 Less resources needed to maintain it.
 Used to detect eavesdropping in quantum key
distribution.

DISADVANTAGES
 Setup is expensive.
 Signal is limited upto approx. 90km.

FUTURE SCOPE
 The experiments suggests transmission to satellites is
possible, due to the lower atmospheric density at higher
altitudes.
 The current commercial systems are aimed mainly at
governments and corporations with high security
requirements.
 Factors preventing wide adoption of quantum
cryptography outside high security areas include the cost of
equipment, and the lack of a demonstrated threat to
existing key exchange protocols

CONCLUSION
• Quantum cryptography is a major achievement in
security engineering.
• As it gets implemented, it will allow perfectly secure
bank transactions, secret discussions for
government officials, and well-guarded trade secrets
for industry!

quantum cryptography

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