Naman quantum cryptography
PUT my all effort to make quantum cryptography easily understandable by the help of basics n videos.Its enough to give you better knowledge about quantum cryptography. Its really interesting topic ;).
Published on: Mar 3, 2016
Transcripts - Naman quantum cryptography
Mr. Manas Singhal
EC 3rd Year
What is cryptography?
Advantages and Limitations of cryptography
RSA Crypto Scheme
OTP (One Time Pad)
Public Key Cryptography
QKD (Quantum Key Distribution)
What is quantum cryptography?
Polarization of light
Heisenberg’s Uncertainty Principle
Element of quantum theory
Advantages and Disadvantages of Quantum cryptography
Plain Text -Plain text is a pure sequence of character codes.
Basically its is original message.
Encryption Algorithm – It is the process of encoding
messages or information in such a way that only authorized
parties can read it.
Cipher Text -Cipher text is also known as encrypted or
encoded information. Its is the combination of key and plain
Decryption Algorithm – It is reverse process of encryption.
Eavesdropping- It is secretly listening to the private
conversation of others without their consent.
WHAT IS CRYPTOGRAPHY?
Cryptography (derived from the Greek words kryptos and
graphein meaning hidden writing) is the science of codes and
Cryptography is the art of encoding and decoding messages of
Cryptography is of increasing importance in our technological
age using broadcast, network communications, Internet ,e-mail
Encrypted messages can sometimes be broken by
cryptanalysis, also called code-breaking, although modern
cryptograph techniques are virtually unbreakable.
Fig.1-Block diagram of cryptography
Fig. 2- Process of cryptography
ADVANTAGES OF CRYPTOGRAPHY
It hides the message and your privacy is safe.
Only the person who have the key would be able to
read the desired message.
Key can be hacked easily.
RSA stands for Ron Rivest, Adi Shamir and Leonard Adleman.
RSA consist a single key.
It provide more security but still it can be hacked.
It take lot of time to generate and regenerate the code.
OTP (ONE TIME PAD)
One-time pad (OTP) is an encryption technique that cannot be
cracked if used correctly.
Fig.3- Example of one time pad
Here the problem raises how to get the key to the decrypting
party safely or how to keep both keys secure.
One-time pads have sometimes been used when the both
parties started out at the same physical location and then
separated, each with knowledge of the keys in the one-time
The key used in a one-time pad is called a secret key.
Ideally destroy the key after use, to make your data to more
Key distribution problem led to the invention of public
PUBLIC KEY CRYPTOGRAPHY
Public-key cryptography, also known as asymmetric
Requires two separate key, one of which is secret (or private)
and one of which is public.
It has better speed and less complicated then RSA and one time
But still there is a problem that is , it can also be hacked.
QUANTUM KEY DISTRIBUTION
Quantum key distribution (QKD) uses quantum mechanics
to guarantee secure communication.
Quantum Key Distribution tell us all attempts of
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.
It is more secure then others schemes.
There is a problem that the finest optical fiber have limit
of 50 km.
WHAT IS QUANTUM CRYPTOGRAPHY ?
Although the field of cryptography is ancient, but it is not
static. Quantum cryptography is a relatively new concept in
Basically quantum cryptography is combination of OTP and
Quantum cryptography is based on two important
a) Polarization of light.
b) Heisenberg’s uncertainty principle.
POLARIZATION OF LIGHT
Polarized light waves are light waves in which the
vibrations occur in a single plane.
The process of transforming unpolarized
light into polarized light is known as polarization.
Vertical polarization - ↑
45° polarization - ↗
135° polarization - ↖
Fig.4- Polarization of light
HEISENBERG’S UNCERTANITY PRINCIPLE
According to the principle two interrelated properties
cannot be measured individually without affecting the
The principle is that you cannot partition the photon
into two halves without affect it value.
So if someone tries to detect the state of photons being
send over to the receiver the error can be detected.
ELEMENT OF QUANTAM CRYPTOGRAPHY
Light waves are propagated as discrete quanta called photons.
Photons are massless but they have energy, momentum and
angular momentum which is called spin.
Spin carries the polarization.
If on its way we put a polarization filter a photon may pass
through it or may not.
We can use a detector to check of a photon that has passed
through a filter
A quantum bit or qubit is a unit of quantum information.
Qubits are not like to simple bits because they have equal
Exists as a ‘0’, a ‘1’ or simultaneously as a superposition
of both ‘0’ & ‘1’ .
Though the amount of information that can be retrieved in
a single qubit is equal to one bit, the difference lies in the
processing of information.
Here the message is send through the public network where as
key send is through quantum channel.
Fig.5- Quantum communication
BB84 was the first security protocol implementing Quantum
It uses the idea of photon polarization.
The key consists of bits that will be transmitted as photons.
Each bit is encoded with a random polarization basis!
First thing is matter in it that is secure connection.
After that the connection is secure and no need to distribution
of key again and again,
Table 1 -Comparing measurements
Alice’s Bit 0 1 0 1 1
Basis + × × + ×
Basis + + × + ×
Bob’s Bit 0 0 0 1 1
The bits allow Alice and
Bob to secure the channel
for key distribution.
× + × +
0 0 1 1
Table 2- Basis value
Table 3- Getting the final key basis
As long as no errors
have occurred. Alice
and Bob have now made
sure that the channel is
Bit 0 1 0 1 1
Basis + × × + ×
Basis + + × + ×
Bit 0 0 0 1 1
The first prototype implementation of quantum
cryptography was built at IBM(International Business
Machine) on 1989.
Fig.6- First prototype
ADVANTAGES OF QUANTUM
Advantages of Quantum cryptography is un-hackable.
Simple to use.
Quantum cryptography the signal is currently limited to approx.
Setup is expensive.
Find the another path for key distribution because of the
limitation of quantum cable.
Make it more secure , so that in future also it can’t be
Quantum cryptography is a major achievement in security
It secure our data transmission as it is never before.
Easy to understand and easy to use.
As it gets implemented, it will allow perfectly secure bank
transactions, secret discussions for government officials, and
well-guarded trade secrets for industry.
Miss. Payal P. Kilor, Mr.Pravin.D.Soni” Quantum Cryptography:
Realizing next generation information security”ISSN 2319 – 4847,Volume
3, Issue 2, February 2014 pp. 286-289.
Simmon, G. J. ,“Symmetric and asymmetric encryption”, ISSN 2319 –
4847,Volume 3, Issue 2, February 2014. pp. 305-330.
Avanindra Kumar Lal, Anju Rani, Dr. Shalini Sharma” The New
Approach of Quantum Cryptography in Network Security” ISSN 2250-
2459, Volume 3, Special Issue 2, January 2013 pp.122-126.
G. Ananda Rao a, Muduganti Rathan Reddy” A note on Quantum
Cryptography”, ISSN : 0975-3397 Vol. 4 No. 09 Sep 2012 pp. 1540-1544