Researchers at StarkWare have proposed a scheme to achieve "quantum-safe" Bitcoin transactions without a soft fork.

Researcher Avihu Levy has proposed a quantum-safe Bitcoin (QSB) scheme that makes Bitcoin transactions quantum-resistant using only existing traditional script constraints. According to this scheme, standard Bitcoin transactions rely on ECDSA (Elliptic Curve Digital Signature Algorithm) signatures, which can be broken by sufficiently powerful quantum computers running Shor's algorithm. To address this issue, the researchers proposed QSB, which replaces the reliance on elliptic curve cryptography in transaction security with a Binohash-based construction that uses a one-time signature scheme embedded in the Bitcoin script. Binohash achieves transaction integrity through a proof-of-work puzzle based on signature length. However, the paper points out that quantum computing can also break this puzzle. QSB eliminates this vulnerability by creating a "hash-to-signature" puzzle that requires the payer to solve a puzzle based on pure hashing rather than elliptic curve mathematics, thus making it resistant to quantum attacks that break elliptic curve cryptography. "Since this puzzle depends only on the anti-image capability of RIPEMD-160 (and not any elliptic curve assumptions), it is completely unaffected by Shor's algorithm," the researchers explained. (The Block)