Bitcoin developers have recently revisited the long-term network security concerns arising from the advancement of quantum computing, known as "Q-Day." This discussion was sparked by an interview between StarkWare CEO Eli Ben-Sasson and journalist Pete Rizzo.
Ben-Sasson believes that without implementing "quantum fixes," Bitcoin will lose its leading position, and its market capitalization will collapse due to the physical limitations of current computing systems.
Adam Back, the creator of Hashcash, co-founder of Blockstream, and one of the cryptographers mentioned by Satoshi Nakamoto in the Bitcoin white paper, criticized these predictions on the social network X, saying, "Guys, don't be silly, don't be alarmist."
Back believes the associated risks are exaggerated, as algorithms designed to counter quantum threats are already in the protocol planning phase. He notes that Ben-Sasson’s own company, StarkWare, is also built on STARK technology, which is a zero-knowledge proof based on cryptographic hash functions.
In the Bitcoin technology community, hash functions are considered a primary security factor. According to theoretical models, a quantum computer running Shor's algorithm could break the asymmetric encryption systems currently used by the network, namely ECDSA and Schnorr.
However, this approach is ineffective against hash functions, including SHA-256. Grover’s algorithm only provides a quadratic speedup for quantum systems in brute-force searches, and Back believes this advantage would be entirely offset by Bitcoin’s standard security settings.
Back's solution: How Bitcoin can survive in the face of quantum supercomputers
As an alternative, Back, associated with Satoshi Nakamoto, cited current technological advancements in the community, which are expected to enter the testing phase by the end of 2026:
- SHRINCS protocol: A modified hash-based signature scheme (Shrunken SPHINCS). According to Blockstream developers, they have optimized it for Bitcoin’s bandwidth constraints.
- Implementation Status: A formal Bitcoin Improvement Proposal (BIP) draft has been released for review. According to the project roadmap, the technology is undergoing stress testing on the Liquid sidechain.
Opponents of post-quantum cryptography often cite data size as the primary concern. Post-quantum signatures are larger than standard 64-byte Schnorr keys; some researchers believe this could overload blockchains and increase transaction fees.
Back believes that infrastructure can be scaled through data aggregation. According to him, batch verification methods and STARK hash proofs can compress thousands of signatures into a compact package. Supporters of this approach argue that it can maintain network speed while preserving decentralization.
The current discussion reveals two distinctly different perspectives: some industry professionals view the quantum threat as an urgent issue, while Bitcoin Core developers state that planning and testing for protective infrastructure are proceeding in parallel with advances in quantum capabilities.