StarkWare says it pushed through a quantum-resistant Bitcoin transaction — by going around the network

StarkWare announced on Wednesday that it completed what it calls the first quantum-resistant Bitcoin transaction, a claim reported by The Block, which cited the company's own announcement and comments from its executives. The technique does not change Bitcoin. It works around it — and it needed a miner's cooperation to land on-chain at all.

The problem being addressed is narrow and specific. A Bitcoin transaction sitting unconfirmed in the mempool reveals the public key material behind its signature. That window — typically minutes — is the point at which a sufficiently capable future quantum computer could, in theory, derive the private key and forge a competing spend before confirmation.

Avihu Levy, head of StarkWare's applications division, devised the workaround, according to The Block's account of the company's statement. It uses "signature grinding": rather than broadcasting the first valid signature the wallet produces, the software discards it and brute-forces millions of candidates until one lands in a form that doesn't expose the vulnerable public key data. StarkWare said the process is deliberately expensive and can consume hours of computation to generate a single transaction.

The bigger constraint is distribution. StarkWare acknowledged that Bitcoin nodes relay only transactions in standard formats, and this one is odd enough that ordinary nodes would drop it. The company said it therefore bypassed the public mempool entirely and handed the transaction directly to a miner — MARA, via its Slipstream service, which accepts non-standard transactions.

Levy still favors a protocol-level fix, per The Block. So does StarkWare CEO Eli Ben-Sasson, who framed the technique as a stopgap: "Avihu's breakthrough is important because it gives the psychological reassurance which we need and which the asset itself needs," he said, adding that crypto has been "behaving like passengers on the Titanic" and that his colleague's work shows "there are lifeboats."

Key facts

• StarkWare announced the transaction on 26 August 2026; reported by The Block (Danny Park), citing StarkWare's announcement and executives.
• Method: signature grinding — brute-forcing millions of signature candidates to avoid exposing public key material in the mempool (StarkWare, via The Block).
• Cost: hours of computation per transaction (StarkWare).
• Non-standard format; not relayed by ordinary nodes. Mined by MARA through Slipstream (StarkWare, via The Block).
• StarkWare's stated position: a protocol-level upgrade, i.e. a fork, is still required for full quantum safety.

The real-world read

Everything here traces to a single interested party. StarkWare is a zero-knowledge-proof company with a commercial stake in post-quantum cryptography being taken seriously; it announced its own result, and no independent verification — a transaction ID, third-party replication, MARA confirming its side — appears in the coverage. The Block is reporting the claim, not testing it.

The framing also does heavy lifting. StarkWare presents this as countering the idea that a fork is the only path — then both Levy and Ben-Sasson say a fork is what's actually needed. Ben-Sasson's own word for the benefit is "psychological reassurance," which is not a security property. And a transaction that costs hours of compute, can't be relayed, and requires a specific miner to accept it out-of-band is a demonstration, not a defense anyone can currently use. What's conspicuously unsaid: what it cost, whether it's repeatable at scale, and how MARA came to be the counterparty.

Opinion, and whose

• Eli Ben-Sasson (StarkWare CEO): the method offers "psychological reassurance" and functions as a lifeboat until a permanent fork lands — "not a reason to relax," but to build more.
• Avihu Levy (StarkWare): despite authoring the workaround, prefers a protocol-level upgrade.
• Both are employees of the company making the announcement. No outside cryptographer's assessment has been published.

Sources

• The Block, Danny Park (26 Aug 2026) — the sole account here: StarkWare's announcement, the signature-grinding mechanics, the MARA/Slipstream detail, and the Ben-Sasson quotes. The Block discloses that Foresight Ventures is its majority investor. Its report relays StarkWare's claims; the underlying announcement is company communication, not independent testing.

Not financial advice.