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. 

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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.