Quantum resistance refers to the ability of cryptographic systems to withstand attacks from quantum computers. Or to avoid quantum computers stealing all the blocks for themselves to add to the blockchain.
These powerful machines leverage the principles of quantum mechanics to solve problems much faster than classical computers. To understand quantum resistance, let’s first look at quantum computing and why it poses a unique threat to the cryptographic foundation of blockchains.
What is Quantum Computing?
Quantum computing is an advanced field where computations are processed in ways that go beyond the binary constraints of classical computers.
Unlike traditional computers, which operate with bits (values of 0s and 1s), quantum computers use qubits, which can represent both 0 and 1 simultaneously thanks to a phenomenon called superposition.
This, combined with entanglement (where qubits become interlinked and influence each other regardless of distance), allows quantum computers to perform complex calculations at speeds that are unimaginable for today’s most advanced supercomputers.
Quantum computing has many applications, from advanced scientific research to optimizing logistics and solving cryptographic problems that are currently considered secure. However, the massive computing power of quantum machines introduces a new risk for cryptography, especially for cryptographic algorithms that safeguard financial systems, data privacy, and blockchain networks.
The Quantum Threat to Blockchain
Blockchains‘ security rests on public-key cryptography, which allows users to create secure digital signatures and protects data through encryption.
Most blockchain protocols today rely on algorithms like RSA and Elliptic Curve Cryptography (such as Verkle Trees) to protect these signatures and encrypt transactions. These algorithms are designed to be resistant to attacks from classical computers, which would require an impractical amount of time to break them.
However, quantum computers are uniquely equipped to break this encryption.
Algorithms such as Shor’s algorithm allow quantum computers to factorize large numbers and solve the discrete logarithm problem with relative ease. While a classical computer would take billions of years to brute-force an ECC-protected private key (like in Ethereum), a sufficiently advanced quantum computer could potentially do this in seconds or minutes.
This threatens the security of public and private keys on blockchains, leaving users’ assets vulnerable to theft if quantum attacks become feasible.
Quantum Resistance Solves The Problem
Quantum resistance, also called post-quantum cryptography, is the development and use of cryptographic algorithms that remain secure even in the face of quantum computing power. Quantum-resistant cryptography focuses on algorithms that cannot be easily solved by quantum computers, thereby maintaining the integrity of cryptographic systems in a quantum-enabled future.
Several approaches are being explored to make blockchains quantum-resistant:
- Lattice-based cryptography: This approach relies on the difficulty of finding specific points in a lattice structure, a problem that even quantum computers struggle with efficiently.
- Hash-based signatures: Using hash functions in signature schemes is quantum-resistant since hash functions are difficult for quantum algorithms to reverse.
- Multivariate quadratic equations: These complex mathematical structures present challenges that are tough for quantum computers to solve quickly.
- Supersingular isogeny-based cryptography: Although newer, this method leverages the difficulty of mapping certain mathematical structures in a way that resists quantum attacks.
Developing quantum-resistant blockchains ensures that, as quantum computing technology matures, blockchains and their users can still securely interact with their networks without the risk of their cryptography becoming obsolete.
