A StarkWare researcher has completed what the company describes as the first quantum-resistant Bitcoin transaction on the Bitcoin mainnet. The milestone demonstration utilized a method known as Quantum Safe Bitcoin (QSB), developed by StarkWare researcher Avihu Levy. According to TradingView, the transaction was confirmed in Bitcoin block 964,199 after spending a 10,000-satoshi output protected by the QSB scheme.
StarkWare Researcher Executes First Quantum-Resistant Bitcoin Transaction
The demonstration moves Levy’s conceptual proposal from theory into a working, onchain execution. By operating entirely within Bitcoin’s existing consensus rules, the test challenges the long-held belief that a network-wide fork is the only path to protect Bitcoin holdings against future quantum computing attacks.
How the Quantum Safe Bitcoin Scheme Works
Standard Bitcoin transactions rely on Elliptic Curve Digital Signature Algorithm (ECDSA) cryptography to prove ownership of funds. Researchers warn that a sufficiently powerful quantum computer running Shor’s algorithm could theoretically break this cryptography by deriving private keys from exposed public keys during the roughly 10-minute confirmation window.
The QSB method swaps out this vulnerable security model by combining hash-based one-time signatures with computational searches that bind an authorization to a specific transaction. Instead of relying on elliptic curves, the scheme relies on the mathematical hardness of reversing hash functions, which quantum computers cannot easily break.
The mechanism utilizes signature grinding to limit the exposure of public-key material while transactions wait in Bitcoin’s mempool. The locking script must be placed as a bare output because it exceeds the standard Pay-to-Script-Hash (P2SH) 520-byte redeem script limit, operating within Bitcoin’s legacy script constraints of 201 opcodes and a 10,000-byte script limit.
Costs, Limitations, and Direct Miner Submission
Despite its successful execution, the QSB method is not currently practical for everyday consumer transfers. The process requires substantial computational resources, involving hours of work across specialized hardware.
* Compute Cost: Generating the transaction requires GPU computation estimated between $75 and $150, with actual expenses reported by StarkWare in the low hundreds of dollars. * Hardware Requirement: Initial testing successfully executed the GPU pinning search phase using eight Nvidia RTX PRO 6000 GPUs over approximately six hours. * Mempool Bypass: QSB transactions are classified as nonstandard under Bitcoin Core’s default relay policies. Ordinary nodes will not propagate the format through the public mempool. * Direct Submission: To achieve mainnet inclusion, the test transaction had to bypass standard relay nodes and be submitted directly to MARA’s Slipstream service for mining by MARA Pool.
Broader Context and the Push for Protocol-Level Upgrades
The breakthrough arrives amid mounting urgency surrounding quantum computing threats. A March research paper by Google Quantum AI concluded that breaking Bitcoin’s elliptic-curve cryptography could require fewer than 500,000 physical qubits, potentially allowing an attacker to derive a private key from an exposed public key in about nine minutes.
While QSB offers a functional safety net for individual users willing to bear the computational expense, StarkWare representatives emphasize it is a last-resort measure rather than a permanent network-wide fix. StarkWare CEO Eli Ben-Sasson noted that while QSB proves individual holdings can be secured today, a protocol-level upgrade through a soft fork remains necessary for broader network protection. Bitcoin developers are separately evaluating alternative proposals, such as BIP-360, which aims to introduce a Pay-to-Merkle-Root output type while removing Taproot’s quantum-vulnerable key-path spend.
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