(aka The Love Story between Quantum Computing and Blockchain). Will quantum computers destroy or protect blockchain? How will security be impacted in the future?
Once quantum supremacy is achieved in the quantum era and quantum, critics say that these universal quantum computers will have the capacity to put blockchain’s future at an end ( bye, blockchain). But what if blockchain was incorporated into quantum computing, creating a quantum blockchain more secure than either of them alone?
Chains of blocks holding data and computers with qubits seem to be two completely different fields in the outer layer. They are, in structure and mechanisms, but their goals and future potential is the same. That goal is security.
Quantum Computers
Quantum computing is a hypothetical model of computation that uses quantum phenomena, including entanglement, superposition and tunneling. The mechanics of this quantum phenomena can then be applied to manipulate information within a quantum computer. Unlike classical computers, quantum computers use quantum bits, or qubits, to encode information in either 1s, 0s, or 1s and 0s at the same time.
This brings on to the topic of superposition, which is the ability of quantum systems to be in a few states at the same time. A common representation of this is through coins. In a fair coin, tails represents 0 and heads represents 1. Flipping a coin would lead to the result of either heads or tails. When spinning a coin, it is unsure whether the coin is heads or tails, since each of the sides of the coins alternating so fast. It appears to be both heads and tails at the same time.
Entanglement is the extremely strong correlation between quantum particles. They exist and are intimately linked in perfect unison, the actions performed on the first quantum particle affect the actions performed on the second particle. This still applies when they’re spatially separated, even if they’re on opposite sides of the universe, a term Einstein referred to as spooky action at a distance.
Quantum computers operate completely differently (with different principles and function sets) compared to classical computers. Therefore, a new set of algorithms needs to be placed that can’t run on classical computers. These special algorithms made exclusively for quantum computers make use of quantum effects and phenomena.
With superposition and entanglement, quantum computers can perform vast amounts of problems and tasks simultaneously. As opposed to classical computers who test out each scenario one by one, quantum computers are able to search through a space of all potential solutions to find the best solution very efficiently. Superposition with two qubits can result in four scenarios while superposition with four qubits can result in sixteen scenarios, represented all at the same time.
Blockchain
The potential quantum era will deeply affect another emerging technology, Blockchain, as it’s chief-support is literally public-key cryptography integrity.
Blockchain enables the transferring of digital coins (like Bitcoin) or assets from one individual to the other. It is a decentralized network with a distributed ledger, where everything is open to anyone. Blockchain’s security comes from its hashing and proof work mechanism and distribution feature.
With a distributed ledger, it uses a peer-to-peer network where everyone is allowed to join and see every single transaction being made, similar to a shared google document. Each member gets a full copy of the blockchain and uses this to verify that everything is in order. A record is kept, whose authenticity can be verified by the community of nodes. This record-keeping is in a shared form which ensures that no single organization controls the entire system, also automatically eliminating the use of middlemen.
When a new block is sent, it is transmitted to everyone in the community and by consensus, will add the block to the existing blockchain. Since all transactions are on the public distributed ledger, no individual can add or alter the blockchain without being permanently recorded, making it specifically tamper-resistant.
With the hashing system, once information is recorded in the blockchain, it becomes extremely difficult to change it, resulting in making all the following blocks after it invalid.
In a blockchain, each block contains a timestamp when it was generated, data, hash, and hash of a previous block. An example of data would be the sender, receiver and the amount of money sent in a Bitcoin. The hash identifies the block and all of its content in a unique sequence (like a QR code or fingerprint). Each block also contains the hash of the block preceding it, creating a chain of connected blocks. If a hacker attempts to make changes to a block, the hash would change, also affecting all blocks following it. In addition, the proof of work mechanism that slows down the creation of new blocks makes it additionally hard to tamper with.
Not only is blockchain more convenient and direct, saving both time and money, it is also highly secure.
Are Quantum Computers a threat to Blockchain?
Well, as of right now, quantum computers don’t have enough qubits to complete any of these specific tasks, including quantum key distribution. However, estimates say that their arrival is approaching and based on the pace of development through the years, can be anywhere from 10–15 years from now.
But what happens when that quantum era starts? First, consider the basis of blockchain. Its distributed ledger causes it to be decentralized and therefore impossible to hack. However, quantum computers will also have the capacity to alter the data contained in a block in such a way to not change the hashing function. With the hashing function seemingly unaltered, the chain will appear to be undisturbed and unaffected. Blockchain’s security is made up of cryptographic functions, where powerful quantum computers will be able to break the cryptographic protection. This appears to render Blockchain as completely pointless and useless against quantum computers.
Nobert Goffa of ILCoin explains his view on the effects of Blockchain with quantum computing:
“If somebody has a quantum based mining pool, it’s easy to dominate others…A lot of companies have been working on quantum-based computing technology. We believe that in the next five years it could be real.”
There are two main ways on how quantum computing endangers blockchain:
- One-way mathematical functions vs. reverse calculations
With Blockchain:
- Uses one-way mathematical functions, including digital signatures
Examples include 1) trapdoor function: computes an inverse function only if given additional information. 2) One-way hash function: marks input messages and generates a fixed length sequence in the output. The values from the input data can easily be computed, but the original input cannot be determined.
- The running process of computing with given data is easy
- Very difficult to compute their inverse functions and perform reverse calculations on a classical computer
With Quantum Computing:
- Are more familiar with reverse calculations and can calculate them quickly
- Leads to scenarios where hacker with access to quantum computer can 1) manipulate transaction history 2) forge signatures 3) double (or triple) spend coins 4) gain access to someone’s assets by pretending to be that user
Data in the transactions are changed silently (without changing the hash) by:
- Changing the record
- Encrypting the result
- Check if the hash value is the same
- If not (the large majority of the time), the process is done over again until the match is found
This brute force attack is extremely tedious for classical computers (over huge, huge time scales) but the result can be generated much quicker with quantum computers. Quantum computers also have the potential to calculate the private key using the public key, putting a huge risk to the elliptic curve signature scheme.
2. Jeopardizing public-key cryptography
Quantum computers can easily jeopardize public-key cryptography used by Blockchain.
They are, in short, very clever and can solve difficult problems in mathematics, including factoring extremely large numbers with Shor’s Factoring Algorithm. This extreme difficulty of factoring large numbers are what makes up the security of public-private key systems. With RSA:
- Seen in web browsers, emails, shopping websites and other forms of communication
- Knowledge of the two prime numbers is required to decode this message using the public key
- Quantum computers have the ability to factor out number in seconds
- Allows quantum computers to crack many systems that keep our online information secure
However, it doesn’t stop here! As one door closes, new possibilities open, including the implementation of quantum-based cryptographic systems, which will be much more secure.
Secure cryptographic key distribution
- Algorithm that can only be run on quantum computer
- People are able to send unhackable data through a quantum network
- Uses the quantum key distribution idea
- Random keys are distributed at a distance between two servers, the keys and encrypted message are sent separately
- Any attempt to measure the quantum system will disturb it
- Unmatching keys indicate hacker is present
The key part to this is entanglement, where the key creator sends qubit pairs to the recipient. The no-cloning theorem is introduced, where a quantum message cannot be stolen without some form of disturbance that will be obvious to the sender and receiver. Anyone who intercepts in this network and reads the entangled qubit will automatically affect its companion qubit at the sender. In this way, the sender and receivers can figure out which keys were transmitted securely and which ones were hacked while transmitting.
Rakesh Ramachandran, CEO and co-founder of QBRICS Inc, states his views on the future of cryptography:
“Quantum computers will be redefining cryptography of not only blockchain but wherever there is an application of cryptography including simple things like an online banking website. There is a considerable research and work being done to mitigate the effects and move to quantum-resistant cryptography or post-quantum cryptography.”
So yes, from this evidence, quantum computers may have the capacity to overpower blockchain. However, quantum computers are unable to break the actual cryptographic code (though they are able to get through the cryptographic protection and gain some access). From this view and with these limits, quantum computing will not completely compromise blockchain.
In this case, what do we do? Which technology should we focus on? Rely on quantum computers that won’t emerge for a while, or Blockchain that is already being used today and still being developed?
The answer: incorporating both and adding blockchains to quantum cryptography, making the entire blockchain into a quantum phenomena.
Quantum Blockchain — The Time Machine
This idea of incorporation is to make a blockchain quantum-based computer. A Quantum Blockchain, also known as a Quantum Time Machine, is a theory Del Rajan and Matt Visser proposed which reflects this exact approach.
Data is encoded in a quantum particle which becomes a quantum block. When new data is added, the second particle’s data is combined with data from the first particle, which entangles it, creating a second block. The first block is then discarded and the first block’s transaction records are kept with the second block. This process is repeated for the third, fourth, fifth… block, creating a chain.
Entanglement is central to this theory, where the use of entanglement is required. Quantum particles are entangled within both space and time, particles existing in the same state even if they’re millions of light years away from each other.
Entanglement in Space — Method 1
The use of entanglement in space is widely operated in many applications of quantum computing, which includes quantum key distribution. What provides this ultimate security in quantum computers is how fragile entanglement is. Measurement, observation, change in temperature, exposure to different environment or any other interaction will create a disturbance. This causes the quantum particle to decohere, or lose its quantum state, becoming obvious if a hacker decides to interfere with a pair of quantum particles.
Entanglement in Time — Method 2
With the focus of time, a particle, specifically a photon, existing in the present can be entangled with another particle existing in the past.
First, the entangled photons are linked in chronological order based on time, the transaction records within them. Because the two particles are entangled, changes in the quantum state of the present photon affect the state of the photon in the past and vice-versa, even if they don’t coexist at the same time.
The measurements of the most recent photon in the record are influenced by the first photon in the past before being measured. If a hacker tried to access a block in the records, it would be invalidated and physically impossible because the entangled photon represented which is in the past no longer exists. Photons within a quantum blockchain and can still be read and analyzed, but are only a copy and cannot be tampered or touched, with exception to the most recent photon that actually exists in the current time.
“We can interpret our encoding procedure as linking the current records in a block, not to a record of the past, but linking it to the actual record in the past, a record which does not exist anymore…the attacker cannot even attempt to access the previous photons, since they no longer exist. They can at best try to tamper with the last remaining photon, which would invalidate the full state.”
Quantum Blockchain Using Entanglement in Time — Del Rajan and Matt Visser
The hacker is only able to access the most current block in the record. However, accessing it would invalidate all blocks following after it, causing a disturbance which alerts everyone in the network. Ideally, you are unable to access previous photons because they no longer exist, but they are still visible because the photons from the two instances of time are entangled. This manipulation of time while providing high security, gives its name of a time machine.
The entanglement in time provides a far greater security benefit than an entanglement in space.
- Del Rajan and Matt Visser
What’s next for the future?
Blockchain and quantum computing are newly developed technologies that will both revolutionize the data industry and optimize security in the future. While Blockchain does contain specific properties that make it impossible to hack, Quantum computers, taking advantage of quantum phenomena, will seemingly be able to override Blockchain’s security. Quantum-resistant cryptography will have to emerge. It is more likely for Blockchains to evolve and develop with quantum computing than quantum computing completely exterminating Blockchain’s whole existence. Incorporations of the two technologies creating ultimate Quantum Blockchain or Quantum Time Machine will make every single transaction ever produced tamper-proof and secure. So long and farewell hackers.
This however won’t be achieved for a while as it requires the quantum internet to be up and running. The quantum web is required, which is a network of quantum routers that can transmit quantum information and still keep their properties intact. This idea, lovely as it is, won’t be approaching for a very long time. When the time does come, let’s just say that security will be just simply revolutionized.
Key Points
- Quantum computers takes advantage of quantum phenomena, including entanglement and superposition
- Superposition is a quantum system’s ability to be in a few states at the same time
- Entanglement is the strong connection between two particles, one particle’s actions influencing the other’s
- Quantum computers have the potential to complete specific tasks much more efficiently than classical computers
- Blockchain is a decentralized network that enables the transferring of digital assets
- Blockchain is secure from its distributed ledger and hashing system
- Quantum computing threatens blockchain in quantum cryptography and in reverse calculations
- Incorporating both quantum computing and blockchain together is Quantum Blockchain, which is highly secure and completely tamper-proof
- Quantum Blockchain is also known as a quantum time machine as it takes advantage of time entanglement properties
If you liked this article, add a clap and stay in tuned for more articles!
Reach out to me at aliceliu2004@gmail.com
LinkedIn: http://linkedin.com/in/alice-liu-16ba6818b
