Avihu Levy, chief product officer at StarkWare, published a proposal on April 9 that provides Bitcoin users an emergency option for quantum-safe spending. The scheme allowed holders to execute individual transactions without waiting for network-wide consensus votes.
- StarkWare’s Avihu Levy proposed Quantum Safe Bitcoin, a hash-puzzle method enabling secure transactions without requiring a network-wide consensus fork.
- Individual transactions cost between $75 and $150 in GPU compute while targeting a specific 1 in 70 trillion hash match.
- The protocol allows institutional whales to bypass long Bitcoin Core upgrade timelines, though it currently requires direct miner submission via Slipstream.
The downside is obvious. You burn roughly $75 to $150 in cloud GPU compute for each one. That math only pencils out if you’re protecting serious size.
This landed the day after Lightning Labs CTO Olaoluwa Osuntokun posted his zk-STARK prototype. Osuntokun’s tool focuses on rescuing funds, proving you own the coins if signatures ever get turned off in an emergency. Levy’s Quantum Safe Bitcoin, or QSB, handles the other half. It lets you actually spend those coins safely when the pressure builds.
How the Hash Puzzle Actually Works
Every normal Bitcoin spend today uses ECDSA signatures. Quantum computers running Shor’s algorithm can eventually derive the private key from the public data we already broadcast.
Levy turns the problem inside out. The sender runs heavy computation off-chain first. They hunt for a public key whose RIPEMD160 hash produces 20 bytes that look exactly like a valid DER-encoded ECDSA signature when plugged into the script.
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👉 Submit Your PRThe odds are built in on purpose. Roughly 1 in 70 trillion for a clean match under normal hash conditions. You hammer through billions of tries on GPUs. Grover’s algorithm helps a quantum attacker, but the paper still puts effective security around 59 bits in the Grover model. Enough to force real work either way.
Once the puzzle is solved off-chain, you send the finished transaction straight to a miner. It skips the regular mempool completely. Miners see it as a normal legacy script evaluation and stuff it in a block. Nodes don’t have to understand anything quantum. It just validates.
The Cost That Hurts
The GPU work breaks down like this: $25-50 to pin the transaction, then two digest rounds at similar money each. Total hits $75-150 at today’s cloud spot prices. Sometimes reports stretch it to $200 to be safe.
You pay that once per UTXO you want to protect. Small sends? Pointless. Exchange withdrawals? Nobody’s eating that cost on volume.
Right now it only runs on bare legacy scripts. If your coins sit in SegWit or Taproot, you first have to move them with a regular (still quantum-vulnerable) spend. The transaction itself is non-standard. Normal nodes won’t relay it. You need direct miner access, think services like Slipstream.
Wallet tools don’t exist yet. When they show up, they’ll come from specialized teams or hardware vendors. Expect slow rollout.
Quantum Risk Management for Large Holdings
Bitcoin avoids rapid changes by design. Consensus-level upgrades require years of coordination and deployment. Google researchers flagged 2029 as a date that demands close attention. Wealthy holders now possess a paid escape hatch if those timelines accelerate.
Users drop the compute cash, solve the hash puzzle, and move the stack without begging the network for permission. The process feels awkward. The infrastructure remains in its infancy. Leaving large cold holdings exposed to future signature forgeries begins to look more dangerous the longer the quantum clock runs.
For the recovery side of the same headache, read yesterday’s piece on Osuntokun’s zk-STARK prototype: https://chainstreet.io/dev-proposes-quantum-escape-hatch-for-bitcoin-wallets/
Chain Street’s Take
The Levy proposal provides a lifeboat for Bitcoin whales. These holders lack the patience to wait for core developers and the mailing list to finish debating.
Users pay a one-time fee in GPU compute costs. The transaction secures legacy assets against quantum threats today. No soft fork drama exists in this model. No community vote dictates the pace. Retail users likely bypass this tool entirely. Serious holders gain an option right now instead of staring at frozen coins later.
Bitcoin’s stubbornness remains a feature until the moment it fails. Levy and other developers proved that improvisation works inside existing rules when threats become real. This creativity deserves respect. If quantum timelines compress, these escape hatches protect real capital for holders with significant position sizes.
Most participants keep doing exactly what they did before. They stack, they watch, and they monitor how fast the big players adopt these tools when the danger scales.
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