This ppt describes about blockchain, quantum computers and about the security of blockchain. I took three major algorithms for securing blockchain from quantum computers attack.

1. QUANTUM SECURED
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BLOCKCHAIN
Presented By:-Ravi Sahal

2. INTRODUCTION
• Blockchain is a distributed database which is
cryptographically protected against malicious modifications.
• Rely on digital signatures, which are vulnerable to attacks by
means of quantum computers.
• Cryptographic hash functions are used in preparing new
blocks.
• Here we propose a possible solution to the quantum-era
blockchain challenge and report an experimental realization
of a quantum-safe blockchain platform that utilizes quantum
key distribution across an urban fiber network for information-
theoretically secure authentication.

3. Paper Name Publication House
and year
Description
1. Quantum-secured
blockchain
IEEE
2018
A possible solution to the
quantum-era blockchain
challenge and report an
experimental realization of a
quantum-safe blockchain
platform that utilizes quantum
key distribution across an urban
fibre network
2. Quantum Blockchain Using
Entanglement in Time
RESEARCH GATE
2017
Brief description of quantum
blockchain using entanglement
is given and used.
Literature Survey

4. “Blocks” on the blockchain are made up of digital pieces of information. Specifically, they have three parts:
1. Blocks store information about transactions, say the date, time, and dollar amount of your most recent
purchase from Amazon.
2. Instead of using your actual name, your purchase is recorded without any identifying information using a unique
“digital signature,” sort of like a username.
3. Each block stores a unique code called a “hash” that allows us to tell it apart from every other block. Let’s say
you made your splurge purchase on Amazon, but while it’s in transit, you decide you just can’t resist and need
a second one. Even though the details of your new transaction would look nearly identical to your earlier
purchase, we can still tell the blocks apart because of their unique codes.
Working of Blockchain

5. Information Stored In Blockchain…

6. • After a block has been added to the end of the blockchain, it is very difficult to go back and alter
the contents of the block. That’s because each block contains its own hash, along with the hash
of the block before it. Hash codes are created by a math function that turns digital information
into a string of numbers and letters. If that information is edited in any way, the hash code
changes as well.
• In order to change a single block, then, a hacker would need to change every single block after it
blockchain. Recalculating all those hashes would take an enormous and improbable amount of
computing power. In other words, once a block is added to the blockchain it becomes very
edit and impossible to delete.
Blockchain Security

7. Application Of Blockchain

8. Limitations of Blockchain

9. Quantum Computation
Rather than store information using bits
represented by 0s or 1s as conventional
digital computers do, quantum computers
use quantum bits, or qubits, to encode
information as 0s, 1s, or both at the same
time. This superposition of states-along
with the other quantum mechanical
phenomena of entanglement and
tunnelling-enables quantum computers to
manipulate enormous combinations of
states at once.

10. Application Of Quantum Computers

11. Working of Blockchain

12. How Quantum Computers Attack Blockchain
• Quantum Computers now-a-days are majorly used by trained professional hackers For
preforming some unwise deeds.
• Using Quantum Computers they directly attack the Blockchain Database, This is mainly
performed by stealing the encrypted private Key.
• For Example if we consider a Client and a Server. The Server upon connection sends a
public key to the client to transport the encrypted data. The client sends the encrypted
data to the Server, which the Server decrypts using its Private Key.
• The hacker tries millions of different combination of keys to try to Encrypt the data
and then can access the data and make changes to It on his will.

13. • A possible attack scenario is as follows: a malicious
party equipped with a quantum computer works o-line
to forge the database.
• It changes one of the past transaction records to its
benefit and performs a search for a variant of other
transactions within the same block such that its hash
remains the same, to make the forged version appear
legitimate.
• Once the search is successful, it hacks into all or some
of the network nodes and substitutes the legitimate
database by its forged version.
How Quantum Computers Attack Blockchain

14. Quantum
Securing
Algorithms
For Blockchains
RSA
ECC
NTR
U

15. RSA algorithm (Rivest-Shamir-Adleman)
• The RSA algorithm is the basis of a cryptosystem -- a suite of
cryptographic algorithms that are used for specific security services or
purposes -- which enables public key encryption and is widely used to
secure sensitive data, particularly when it is being sent over an
insecure network such as the internet.
• The public and private key generation algorithm is the most complex part of
RSA cryptography. This combination of key is available with the Server to
decrypt the Data.

16. Elliptical curve cryptography (ECC) is a public key encryption technique based
on elliptic curve theory that can be used to create faster, smaller, and more efficient
cryptographic keys. ECC generates keys through the properties of the elliptic curve
equation instead of the traditional method of generation as the product of very
large prime numbers. The technology can be used in conjunction with most public
key encryption methods, such as RSA, and Diffie-Hellman. According to some
researchers, ECC can yield a level of security with a 164-bit key that other systems
require a 1,024-bit key to achieve. Because ECC helps to establish equivalent security
with lower computing power and battery resource usage, it is becoming widely used
for mobile applications.
ECC ALGORITHM

17. • RSA and ECC are vulnerable to quantum computing attacks and the availability of practical quantum
computers is approaching faster than previously believed. Organizations interested in maintaining their
current embedded cryptographic choices but want to immediately future-proof against quantum
attacks are embracing our Quantum Safe Hybrid (QSH) approach.
• NTRU is a lattice-based public key cryptosystem and the most thoroughly researched and widely
NTRU ALGORITHM

18. • It is one of the most Concerning Issues of the 21st Century, and there has been a lot of research
going On at the moment on how to stop quantum computing from being used for evil purposes.
• One of the possible solutions is by using NTRU algorithm.
• Lets consider if in an any ongoing blockchain transaction data is being shared between the client
and the Server and a hacker is attempting to attack the database. But he would not succeed in
doing so because only a quantum computer can stop a quantum computer. While the transaction
of data in Blockchain is going on two quantum atoms entangle with each other causing them to
have all the similar features which cannot be altered.
• Thus if any hacker tries to modify the entanglement, the transaction between will destroy
themselves and
Thus the data will be safe and within the blockchain.
Quantum Secured Blockchain

19. • At the end of the day, the threat of quantum computing reduces to an economic
Viable quantum computers will initially be very expensive and have limited
only governments will be able to afford them and will only have enough capacity
most valuable secrets of other nation states.
• Gradually this capability will trickle down to organized criminals, but again they
the capacity able to attack the most lucrative targets (e.g. falsifying financial
blackmailing large companies or selling their sensitive data to the highest
time quantum computing is generally available (if ever), hopefully the old,
algorithms will have all but disappeared.
The Post-Quantum World

20. CONCLUSION
• we have developed a blockchain protocol with information-
theoretically secure authentication based on a network in
which each pair of nodes is connected by a QKD link.
• A crucial advantage of our blockchain protocol is its ability to
maintain transparency and integrity of transactions against
attacks with quantum algorithms. Our results therefore open
up possibilities for realizing scalable quantum-safe blockchain
platforms. If realized, such a blockchain platform can limit
economic and social risks from imminent breakthroughs in
quantum computation technology.

21. REFERENCES
• L. Gyongyosi, S. Imre, and H.V. Nguyen, IEEE Commun. Surv. Tut. (2018).
• B. Marr, How Blockchain Technology Could Change The World, Forbes, May 27, 2018.
• P. Franco, Understanding Bitcoin: Cryptography, Engineering and Economics.
• https://iopscience.iop.org/article/10.1088/2058-9565/aabc6b
• https://phys.org/news/2018-06-quantum-key-blockchain.html

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