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Bitcoin has survived market crashes, regulatory crackdowns, and more forks than a cutlery factory. The next threat on the horizon is quantum computing, and StarkWare just made the first serious move to address it on mainnet.
On August 26, 2026, StarkWare successfully mined the first quantum-safe Bitcoin transaction using the Quantum Safe Bitcoin construction developed by Avihu Levy, the company’s General Manager of Applications. The transaction ID, 305a24ffea912b9cf428f29ebf952321c96dab5bab284fc0d0801562f5abab07, is now a matter of public record on the Bitcoin blockchain.
What quantum-safe actually means here
Bitcoin’s current security relies on elliptic-curve cryptography, specifically the secp256k1 curve used to generate public-private key pairs. A sufficiently powerful quantum computer running Shor’s algorithm could theoretically reverse-engineer a private key from a public key, which would be a catastrophic vulnerability for any exposed Bitcoin address.
The QSB method sidesteps this entirely by replacing elliptic-curve signatures with hash-based cryptography, specifically Lamport-style hash-based signatures that rely on RIPEMD-160 for pre-image resistance. Hash functions don’t have the same mathematical weakness to Shor’s algorithm that elliptic curves do, making them a more durable foundation when quantum hardware eventually matures.
The construction achieves approximately 118-bit second pre-image resistance. The entire implementation fits within Bitcoin’s existing legacy Script limits: 201 non-push opcodes and 10,000 bytes. No consensus rule changes, no soft fork, no protocol-level negotiations with miners and node operators. It works on Bitcoin as it exists today.
The catch: this is expensive and non-trivial to use
Pulling off a QSB transaction requires significant off-chain computation. Current estimates put the processing cost at between $75 and $150 per transaction, which makes it wildly impractical for buying a coffee or moving small amounts.
The transactions are also nonstandard, meaning they won’t be relayed by regular Bitcoin nodes in the typical way. Getting one mined required going directly through MARA Slipstream, a service that allows nonstandard transactions to reach miners without the usual mempool relay constraints.
StarkWare CEO Eli Ben-Sasson framed the initiative candidly, calling QSB a “passion project” that demonstrates Bitcoin holders can protect their assets from quantum threats right now, at a cost, without waiting for protocol-level changes.
Levy first published the QSB concept alongside an open-source implementation in April 2026. The mainnet version incorporated contributions from StarkWare engineer Tomer Giladi and drew on ideas from Robin Linus’s Binohash scheme, an earlier piece of research into hash-based spending conditions that informed the final design.
Where this fits in the broader quantum-resistance conversation
StarkWare announced a formal post-quantum roadmap for the Starknet ecosystem in June 2026, situating QSB within a larger initiative to harden its infrastructure against future quantum threats. That roadmap also involved collaborative work on BIP 360, a Bitcoin Improvement Proposal focused on quantum-resistant address formats.
By operating within existing Script limits and requiring no consensus changes, QSB removes the biggest bottleneck in Bitcoin’s upgrade process. A user with a high-value wallet doesn’t need to wait for the network to agree on anything. They can move funds into a quantum-resistant construction today, at a cost that is steep but not prohibitive for seven- or eight-figure holdings.
The $75 to $150 per-transaction cost signals where investment attention in this space is likely to flow. Scaling hash-based cryptographic constructions, reducing their computational overhead, and eventually making them relay-compatible with standard Bitcoin infrastructure represent a clear research and engineering agenda.
Disclosure: This article was edited by Editorial Team. For more information on how we create and review content, see our Editorial Policy.
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