Quantum-Safe Bitcoin Transaction Lands on Mainnet

Cryptography company StarkWare has achieved quite a significant feat by performing the first quantum-proof Bitcoin mainnet transaction. It was confirmed in Bitcoin block 964,199.

According to StarkWare researcher Avihu Levy, this proof-of-concept could potentially secure funds against quantum computer attacks. 

Bitcoin did not need a soft fork, new opcode, or network-wide upgrade for this particular transaction.

Bypassing Shor’s algorithm 

Ordinary Bitcoin signatures depend on elliptic-curve cryptography. However, a sufficiently powerful quantum computer running Shor’s algorithm could threaten it in a not-so-distant future. 

QSB uses Bitcoin’s existing scripting rules to create a kind of computational puzzle. The security of this puzzle comes from hash preimage resistance. 

The developers used the MARA Foundation’s Slipstream service to bypass relay limits (ordinary nodes would not propagate the script through the public mempool). 

A stopgap measure 

Bitcoin has not found its final post-quantum solution just yet, meaning that it should be treated as merely a last-resort measure. 

The transaction takes between $75 and $150 in cloud GPU compute, so the computational costs are way too high for QSB to be sustainable. 

Bitcoin will still need a protocol-level soft fork to integrate a scalable alternative. However, the fact that Bitcoin can already execute at least one type of quantum-resistant transaction is quite significant. 

The growing quantum threat

According to the 2025 Quantum Threat Timeline survey, there is a 28–49% probability of a cryptographically relevant quantum computer being developed within the next decade. 

Within the Bitcoin community, the consensus is that a post-quantum migration path should be built now.