Is Quantum Computing a Threat to Blockchain Security

Copyright © Blockchain Council www.blockchain-council.org
Is Quantum computing an existential threat to
Blockchain Technology?
There is a lot of euphoria surrounding Bitcoin and other cryptocurrencies at the
moment, and this has translated to exponential rises in prices over the last year. A
lot of the hype surrounding cryptocurrencies is justified as nearly every industry in
the world can benefit from blockchain technology in one form or another. But
amidst all of the excitement, it is essential to evaluate whether the underlying
technology is resistant to other emerging technologies, namely quantum
computing.
2

Since the fundamental of blockchain technology is focused on ensuring security in
a decentralized fashion, let’s take a look at how quantum technology changes the
equation when it comes to security.
3

How Blockchains work: Public Key Cryptography
Public key cryptography relies on a pair of public and private keys to ensure
secure, encrypted communication on an unsecured channel. Public key
cryptography ensures that the message received by the receiver is untampered
and also that the actual sender created it. For example, if two users Alice and Bob
want to communicate with each other using public key cryptography, they both
can generate public and private keys.
4

As the name suggests, public keys are broadcasted to the entire network while
private keys are kept secure. Now, if Alice wants to send Bob an encrypted
message, she can encrypt the message using Bob’s private key and digitally sign
the message using her private key. This ensures that the message received by
Bob can only be decrypted by him and the digital signature proves that Alice was
the creator of that message.
5

The security aspect of this cryptography scheme comes from the fact that given
the public key, it is practically impossible to come up with the corresponding
private key. In other words, there is no way other than guessing and checking
different private keys. With the current computing resources we have, it would
take an extraordinarily long time to find the correct private key.
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. In other words, there is no way other than guessing and checking different private
keys. With the current computing resources we have, it would take an
extraordinarily long time to find the correct private key. Assuming that a classical
computer tested a trillion keys a second, it would take up to 1.09 x 1019 years to
guess the correct answer. To put numbers into perspective that is roughly about
785 million times longer than the age of the universe (approximately 14 billion
years) because public key cryptography relies on prime numbers for key
generation.
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The Quantum Threat
As it exists, the current paradigm for digital security relies heavily on the sanctity
of the assumptions underlying in the previous section. If quantum computers were
to make our current security framework obsolete, it would also be a disaster not
only for public key cryptography but for all other financial and banking systems as
they exist today.
8

The quantum computing threat comes from the fact that quantum computing takes
advantage of quantum bits or “qubits” that can exist in any superposition of values
between 0 and 1 and can, therefore, process much more information than just 0 or
1, which is the limit of classical computing systems. As a result, quantum
computers can handle many orders of magnitude more than traditional computers.
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Currently, however, quantum computers can only work on a limited number of
highly specific applications. Companies like Google and IBM are working on their
implementations of quantum computers which are said to be a 100 million times
faster than classical modes of computation.
10

How Blockchain will keep up -
If in the future, the threat of quantum computers becomes more pronounced to
public key cryptography, there are many changes that blockchains can implement
to become quantum resistant. Already, projects like the Quantum Resistant
Ledger (QRL) have their implementation of a blockchain that will not be affected
by the exponential increase in computational power of quantum computers.
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QRL ensures quantum resistance by making sure that private keys are generated
in a very complicated way that relies on hash-based cryptography compared to
current public key cryptography. So far as the consensus algorithm of Bitcoin,
Proof of Work is concerned, it could easily be upgraded using a hard fork that has
been used several times in the past. Since quantum computers can make many
hash functions obsolete, the underlying Blockchain of many tokens would have to
change their architecture fundamentally.
12

Blockchain Council Certifications
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space today.
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13

THANK YOU!
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Copyright © Blockchain Council www.blockchain-council.org 14

Is Quantum Computing a Threat to Blockchain Security

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