StarkWare executes first quantum-resistant Bitcoin transaction on mainnet

StarkWare has successfully executed the first quantum-resistant Bitcoin transaction on the mainnet. Developed by Avihu Levy, the Quantum Safe Bitcoin (QSB) scheme uses Lamport-style hash-based signatures to protect assets from Shor's algorithm without requiring a protocol fork. The transaction was mined in block 964,199 by MARA Pool via its Slipstream service, bypassing standard node relay limits. While QSB offers an immediate 'lifeboat' for high-value wallets, its high computational cost of $75 to $200 per transaction and nonstandard format mean a protocol-level soft fork remains the preferred long-term solution.

StarkWare quantum-resistant Bitcoin transaction

• ▪The quantum-resistant transaction was developed by Avihu Levy, StarkWare's General Manager of Applications, with contributions from StarkWare engineer Tomer Giladi
• ▪StarkWare successfully executed and mined the first quantum-resistant Bitcoin transaction on the Bitcoin mainnet on August 26, 2026
• ▪The StarkWare quantum-resistant transaction spent a 10,000-satoshi output in Bitcoin block 964,199 under transaction ID 305a24ffea912b9cf428f29ebf952321c96dab5bab284fc0d0801562f5abab07

Quantum computing threat to Bitcoin

• ▪Bitcoin's current elliptic-curve cryptography, specifically the secp256k1 curve, is vulnerable to private key reverse-engineering by a quantum computer running Shor's algorithm
• ▪Google researchers estimated in March 2026 that a sufficiently capable quantum computer could derive a Bitcoin private key nine to 12 minutes after its public key becomes visible in the mempool

Hash-based signature implementation

• ▪The Quantum Safe Bitcoin implementation fits entirely within Bitcoin's existing legacy Script limits of 201 non-push opcodes and 10,000 bytes, requiring no consensus rule changes
• ▪The Quantum Safe Bitcoin design draws on ideas from Robin Linus's Binohash scheme, which is an earlier piece of research into hash-based spending conditions
• ▪The Quantum Safe Bitcoin scheme replaces elliptic-curve signatures with Lamport-style hash-based signatures relying on RIPEMD-160 for pre-image resistance, achieving approximately 118-bit second pre-image resistance

High transaction processing costs

• ▪Generating a single Quantum Safe Bitcoin transaction requires hours of off-chain GPU computation, costing between $75 and $200
• ▪StarkWare spokesperson Nathan Jeffay stated that the completed mainnet transaction cost in the 'low hundreds of dollars,' specifically estimating the expense at around $150 to $200

Nonstandard transaction relay requirements

• ▪Because Quantum Safe Bitcoin transactions are classified as nonstandard under Bitcoin Core's default relay policies, ordinary nodes will not propagate them through the public mempool
• ▪To bypass standard relay constraints, the StarkWare transaction was submitted directly to and mined by MARA Pool using its Slipstream service

Bitcoin protocol upgrade debate

• ▪StarkWare CEO Eli Ben-Sasson and researcher Avihu Levy both advocate for a permanent protocol-level upgrade, such as a soft fork, to make the entire Bitcoin network quantum-safe
• ▪Bitcoin developers are separately evaluating BIP-360, a proposed soft fork that would introduce a Pay-to-Merkle-Root output type while removing Taproot's quantum-vulnerable key-path spend

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