• StarkWare announced that researcher Avihu Levy tested a new experimental quantum-resistant Bitcoin transaction on mainnet. The transaction spent a 10,000-satoshi output from block 964,199 while leaving Bitcoin’s consensus rules unchanged.
• The company described the test as the first transaction of its kind. MARA Pool included the transaction in a block after receiving it directly via its Slipstream service, as the transaction’s nonstandard structure prevented it from being propagated by conventional nodes through the public mempool.
• Nathan Jeffay, a StarkWare spokesperson, said the computation cost between $150 and $200. StarkWare said the entire process took several hours, showing that its method can protect a single Bitcoin output under current rules but still requires substantial computing resources and operational support.

How the Quantum-Resistant Bitcoin Transaction Works

• Avihu Levy’s Quantum-Safe Bitcoin (QSB) design was first proposed in April. It combines hash-based one-time signatures with computational searches that connect spending authorization to a specific transaction. The system is designed to remain secure even if future quantum computers become capable of breaking Bitcoin’s existing elliptic-curve cryptography.
• Research from Google published in March suggested that a sufficiently powerful quantum computer could theoretically recover a Bitcoin private key within nine to 12 minutes after its public key is exposed. If that capability becomes practical, attackers could potentially manipulate transactions during the period before confirmation.
• QSB is intended to secure individual Bitcoin transactions rather than overhaul the network’s cryptographic foundation. It enables coins to be placed into protected outputs without requiring changes to Bitcoin’s protocol. However, funds associated with public keys that were already exposed could remain vulnerable until they are transferred.
• The system’s nonstandard transaction format creates another hurdle. Bitcoin Core’s default relay policy prevents ordinary nodes from forwarding the transaction before confirmation. As a result, users must send it directly to a cooperating miner through a service such as MARA’s Slipstream, requiring both advance preparation and specialized miner access.
• StarkWare CEO Eli Ben-Sasson described QSB as a potential temporary safeguard while the Bitcoin ecosystem works on broader quantum-resistant upgrades. The technology offers protection under Bitcoin’s current framework instead of replacing its underlying cryptography.
• At the protocol level, developers are also considering proposals such as BIP-360. The proposed soft fork would introduce a Pay-to-Merkle-Root output type and eliminate Taproot’s quantum-vulnerable key-path spending. Unlike QSB, implementing such a change would require network-wide coordination and activation.
• The StarkWare test demonstrates that quantum-resistant Bitcoin spending can be achieved without altering the network’s current consensus rules. However, the experiment also highlights the computational and operational challenges that must be addressed before such protection can be deployed more broadly.