StarkWare has executed a quantum-resistant Bitcoin transaction on mainnet, sending 3.1 BTC using hash-based cryptography designed to survive attacks from quantum computers. The transaction used QSB, a scheme that replaces Bitcoin's standard elliptic curve signatures with RIPEMD-160 hash-to-signature puzzles.
The move tests a pathway to quantum safety on Bitcoin without requiring a network-wide soft fork. Current Bitcoin addresses rely on elliptic curve cryptography, which cryptographers have long flagged as vulnerable to sufficiently powerful quantum computers. Hash-based signatures are considered quantum-resistant because they depend on collision resistance of hash functions rather than the discrete logarithm problem that quantum algorithms could theoretically break.
QSB works by encoding a spending authorization as a cryptographic puzzle that must be solved on-chain at transaction time. The sender commits to a hash of their signature in advance, then publishes the signature itself during settlement. A Bitcoin node verifies the hash commitment matches the published signature, accepting it as valid. The scheme trades computational overhead for quantum durability: according to prior analysis, quantum-safe Bitcoin transactions using this method cost roughly $200 per transaction in fees and block space under current network conditions.
StarkWare, which develops scaling infrastructure for Ethereum and operates the Starknet blockchain, has positioned itself as a research leader on post-quantum cryptography in blockchain systems. The company published the QSB scheme design in 2024 and has been developing implementation paths since then.
Quantum computing timelines remain uncertain, with estimates of cryptographically relevant quantum computers ranging from one to two decades away. Bitcoin's developer community has not yet agreed on a consensus approach to quantum resistance, and no soft fork proposal has gained widespread support. Miners and node operators would need to coordinate any protocol change, and the opportunity cost of Bitcoin development bandwidth competing with other upgrades has kept quantum safety from becoming an immediate priority.
StarkWare's execution of the transaction on mainnet demonstrates that quantum-resistant spending is technically feasible today using Bitcoin's existing script language, without waiting for protocol-level changes. Whether the cost and complexity of the QSB method will appeal to Bitcoin users concerned about quantum risk remains open; the transaction executed successfully but represents a single use case rather than adoption at scale.
The ability to spend Bitcoin with quantum resistance using current rules means users concerned about long-term security of their holdings have an option available now, even if it is more expensive than standard transactions. Whether additional transactions follow, or whether Bitcoin's community settles on different quantum-safety approaches, will determine whether this execution becomes a prototype for a new spending pattern or a one-off demonstration.
