Bitcoin Completes First Experimental Quantum-Safe Transaction, Starkware Says

In brief

• StarkWare says the first quantum-safe Bitcoin transaction has been mined on Bitcoin mainnet.
• The method uses hash-based security without changing Bitcoin’s consensus rules.
• StarkWare still favors a soft fork as a long-term defense against quantum computers.

Starkware, the blockchain infrastructure company behind Ethereum layer-2 network Starknet, says the first quantum-safe Bitcoin transaction has been mined on the Bitcoin mainnet, testing a way to protect funds from future quantum attacks without changing the network’s consensus rules.

In a blog post on Wednesday, Starkware said the transaction used Quantum-Safe Bitcoin, or QSB, a method developed by Starkware researcher Avihu Levy. Levy published the research in April, and Starkware engineer Tomer Giladi later helped turn the proposal into a working mainnet transaction.

“A quantum-safe transaction was mined on the Bitcoin mainnet today that holds up against an adversary running a working quantum computer,” Starkware wrote. “Bitcoin holders now have a way to move coins into storage a quantum computer cannot open.”

Bitcoin uses elliptic-curve cryptography to secure transactions, which a sufficiently powerful quantum computer running Shor’s algorithm could theoretically break to derive private keys and steal funds. Protecting the network could eventually require either a hard fork, which introduces rules incompatible with older software and can split the network, or a soft fork, which can introduce new rules while remaining compatible with older nodes.