Bitcoin Could Be Quantum-Safe Without Protocol Changes

Quantum computing poses a significant threat to the security of Bitcoin transactions, as quantum computers have the potential to break the cryptographic algorithms currently used to secure the network. However, a new research proposal by Avihu Levy of StarkWare offers a promising solution to this problem without requiring any changes to the core rules of the Bitcoin network.

The proposal, known as Quantum Safe Bitcoin (QSB), aims to make Bitcoin transactions resistant to quantum attacks by replacing the reliance on elliptic curve cryptography with hash-based assumptions. This approach shifts the security of transactions to hash pre-image resistance, making them less vulnerable to attacks by quantum computers running algorithms like Shor’s algorithm.

At the heart of QSB is a “hash-to-signature” puzzle, which involves hashing a transaction-derived public key using RIPEMD-160 and treating the output as a candidate ECDSA signature. Only a small fraction of random hashes meet the formatting rules required for valid signatures, creating a proof-of-work condition that significantly increases the difficulty of forging signatures.

One of the key advantages of QSB is that it remains resistant to Shor’s algorithm, offering meaningful security margins against quantum attacks. The construction of QSB works within Bitcoin’s existing scripting limits and does not require any consensus changes or soft forks, making it an attractive option for developers concerned about protocol fragmentation.

While QSB transactions may exceed standard relay policy limits and require direct submission to miners through services like Slipstream, the cost of generating a valid transaction is estimated to be within reach. The paper suggests that total compute expenses range from $75 to $150 using cloud GPUs, with successful puzzle solutions reported after several hours of testing using multiple GPUs.

Although the project is still incomplete and certain aspects of the pipeline, such as full transaction assembly and broadcast, have not been demonstrated on-chain, the proposal adds to the growing body of research exploring how Bitcoin can adapt to the threat of quantum computing. By leveraging existing rules rather than consensus upgrades, QSB presents a promising path forward for enhancing the security of the Bitcoin network in the face of future technological challenges.