On 26 August 2026, a transaction using Quantum Safe Bitcoin (QSB) was confirmed on the Bitcoin mainnet. Developed by StarkWare researcher Avihu Levy, the method protects specific Bitcoin holdings using hash-based security designed to resist attacks from a sufficiently powerful quantum computer, without changing Bitcoin’s existing consensus rules.
How does Quantum Safe Bitcoin work?
Bitcoin currently relies on elliptic-curve cryptography for digital signatures. A sufficiently capable quantum computer running Shor’s algorithm could, in principle, undermine that protection once a public key is exposed. QSB adds a quantum-resistant layer based on hash functions. Importantly, it works within Bitcoin as it exists today: no hard fork, soft fork or protocol upgrade was needed for the demonstration.
That makes the experiment significant. It shows that individual Bitcoin holdings can, under specific conditions, be moved into a form of storage designed to remain secure against this type of quantum attack.
But Bitcoin is not quantum-safe yet
The demonstration is a proof of what is possible, but not a complete solution.
QSB only protects assets after they have been moved into the protected output. It does not retroactively secure Bitcoin whose public keys are already exposed, and it does not make the broader Bitcoin network quantum-resistant. The transaction format is also non-standard and currently requires direct submission to a miner rather than travelling through the normal Bitcoin mempool.
Cost is another challenge. The first transaction required around 3,100 GPU-hours and approximately $320 in compute. Subsequent optimisation work has already reduced the estimated cost considerably, showing how quickly the technology is evolving.
Why this extends beyond Bitcoin
Can digital infrastructure can migrate quickly enough once the risk becomes more concrete? Blockchains are particularly interesting because cryptographic assets may remain accessible for many years. That makes long-term security and migration planning increasingly relevant.
The QSB experiment demonstrates an important principle: quantum readiness can start before a full protocol-wide solution is available. For the wider quantum ecosystem, it is another example of post-quantum cryptography moving from research into actual implementation.
Want to dive deeper?
The original analysis explores how QSB works, which Bitcoin holdings it can protect and why major technical difficulties still remain.
