TLDR
- StarkWare CEO Eli Ben-Sasson warned that Bitcoin needs stronger security against future quantum attacks.
- Blockstream co-founder Adam Back rejected predictions that quantum computing would inevitably cause Bitcoin to collapse.
- Quantum computers running Shor’s algorithm could theoretically break Bitcoin’s current digital signatures.
- Bitcoin’s SHA-256 hashing faces a different and more limited threat from known quantum algorithms.
- Blockstream demonstrated quantum-resistant SHRINCS signatures on the Liquid sidechain in March 2026.
Bitcoin Quantum security has become a renewed point of debate after StarkWare chief executive Eli Ben-Sasson warned that future quantum computers could threaten Bitcoin. Blockstream co-founder Adam Back challenged his forecast, pointing to work on new ways to protect the network and its users.
Bitcoin Quantum Warning Draws Firm Response
In an interview with journalist Pete Rizzo, Ben-Sasson said Bitcoin needs an upgrade before powerful quantum computers can break its current transaction signatures. He warned that failure to act could damage confidence in Bitcoin and cause its market value to fall.
c’mon guys, don’t be silly and alarmist. Eli knows about hashes based signatures – his company implements STARKS (hash based signatures of execution), and a potential way to batch verify hash besed sigs. he also knows about SHRINCS, “find a quantum fix”, there is a draft BIP even
— Adam Back (@adam3us) November 4, 2026
Back rejected the prediction of an unavoidable collapse. His comments followed a separate debate over present threats, including warnings about AI-assisted hackers. Swan Bitcoin founder Cory Klippstein recently argued that attacks using artificial intelligence pose a nearer danger.
Adam Back Distinguishes Signatures From Hashing
Bitcoin uses digital signatures to confirm ownership and a separate hashing system to secure mining. Researchers say a sufficiently advanced quantum computer could break the signatures through Shor’s algorithm and reveal private keys from exposed public keys.
Back said the same threat does not extend directly to Bitcoin’s SHA-256 hashing. Grover’s algorithm could make some searches faster, but it offers a smaller advantage. The timing of any computer powerful enough to attack Bitcoin remains uncertain. No quantum computer has demonstrated that attack against Bitcoin.
SHRINCS Developers Continue Quantum Testing
Researchers are developing SHRINCS, a hash-based signature method designed to resist quantum attacks while limiting transaction size. The work addresses a different problem from recent thefts affecting older BTCPay Server software, which involved conventional security failures rather than quantum machines.
Blockstream tested SHRINCS signatures on the Liquid sidechain in March. A later technical draft described signatures starting at 548 bytes, compared with Bitcoin’s 64-byte Schnorr signatures. The draft remains under review, with further proof and testing required.
Bitcoin Upgrade Faces Network Tradeoffs
Larger signatures could reduce the number of transactions each block holds and increase fees. Developers are studying ways to manage that cost. Elsewhere, Solflare tightened software access after security incidents, reflecting the industry’s separate work on existing threats.
Bitcoin Quantum protection has not been activated on Bitcoin’s main network. SHRINCS has an unnumbered draft specification, but any change to Bitcoin’s transaction rules would need its own proposal and broad support from the network’s participants.
