Quantum Bitcoin Risk Changes as AI Agents Advance

TLDR

• AI agents helped researchers reduce a key quantum attack resource score by 86.1%.
• The research optimized only a secp256k1 point-addition process, not a full Bitcoin private-key attack.
• IonQ estimates a complete attack would require about 1,457 logical qubits and 39 million Toffoli gates.
• Glassnode estimates 6.04 million BTC, or 30.2% of supply, has public-key exposure.
• BIP 360 could reduce some quantum risks but does not automatically protect older or already exposed coins.

AI agents helped more than 100 researchers cut the resource score for a key quantum computing task linked to Bitcoin by 86.1%, according to a paper published on September 9. The work does not show that Bitcoin has been hacked. It shows that software improvements can reduce the quantum resources needed for secp256k1 calculations.

Researchers focused on a narrow part of the attack process rather than a full private-key recovery. The result adds pressure on blockchain developers to plan for post-quantum security before fault-tolerant quantum computers become practical.

AI Agents Reduce Quantum Resource Score

Eigen Labs launched ECDSA.Fail in May to improve secp256k1 point-addition circuits. The contest measured designs by multiplying logical qubit use by average Toffoli gate count.

The score fell from 10.75 billion to 1.496 billion by July 26. One leading design used 1,151 logical qubits and about 1.3 million Toffoli gates. Later entries reduced gate counts below one million, while another design used only 813 qubits.

IonQ estimates that a complete secp256k1 attack would need about 1,457 logical qubits and 39 million Toffoli gates. Its model translates that requirement into 19,397 physical trapped-ion qubits and about 25.7 days of processing time.

Google researchers have published higher gate estimates for a full attack. Their models use about 1,200 to 1,450 logical qubits and between 70 million and 90 million Toffoli gates. ECDSA.Fail cannot be compared directly because it improves only one subroutine.

Millions of Bitcoin Already Exposed

Glassnode estimates that 6.04 million BTC, or 30.2% of supply, has public keys exposed on-chain. About 1.92 million BTC sits in directly exposed outputs, while 4.12 million BTC faces exposure linked to user behavior such as address reuse.

Another risk appears when a hidden public key becomes visible after spending. A sufficiently fast quantum computer could, in theory, derive the private key before the transaction receives confirmation.

BIP 360 proposes Pay-to-Merkle-Root outputs to reduce exposure from Taproot key-path spending. However, it does not remove the short mempool risk or move older coins automatically.

A Coinbase advisory report says about 1.7 million BTC remains in early P2PK addresses linked to Satoshi or lost wallets. Developers must decide how migration rules should treat dormant coins. Ethereum targets broad quantum resistance by December 2029, while the G7 has also urged coordinated post-quantum planning across finance under future migration plans.

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