# Quantum Computing Firm Estimates 30,000 Qubits Could Crack Bitcoin Keys Alice & Bob researchers suggest a specific qubit threshold for breaking elliptic curve signatures. - **Source:** [CryptoPotato](https://brifing.si/source/bd22636b-ec8d-42a8-8cca-1937c50e0f6c) - **Published:** 2026-10-29 - **Topic:** [Software & Engineering](https://brifing.si/c/engineering) - **Original article:** - **On Brifing:** https://brifing.si/s/22c6fc1e-f0a4-4603-b833-bf9ddab0a8aa ## Quantum Threat to Bitcoin Alice & Bob researchers recently published a preprint estimating that 29,588 physical cat qubits could compromise Bitcoin private keys. The study targets the secp256k1 elliptic curve, which secures signatures. This theoretical attack requires approximately 61.8 minutes to execute, assuming the system successfully reuses circuits originally compiled for breaking RSA-2048 encryption standards. ## Cat Qubit Hardware Advantage The company utilizes proprietary superconducting cat qubits designed to suppress bit-flip errors directly at the hardware level. By mitigating these errors, the architecture reduces the total number of physical qubits required for each logical error-corrected qubit. This design shift significantly lowers the hardware overhead compared to traditional superconducting quantum computing approaches. ## Comparison with Google Estimates Google Quantum AI previously proposed an attack requiring fewer than 500,000 physical qubits to crack keys in nine minutes. While Google's model targets on-spend attacks, Alice & Bob's hour-long duration exceeds the 10-minute Bitcoin block time. This suggests that transactions in progress remain protected from this specific, slower quantum-based decryption method. ## Targeting Legacy Address Types The threat primarily concerns Pay-to-Public-Key scripts, an early address format that exposes public keys directly on the blockchain. Researchers identified over 1.7 million BTC held in these vulnerable legacy addresses. These include coins from the Satoshi era, which are considered the most likely initial targets for any future quantum-capable adversary. ## Assumptions and Error Rates The current 30,000-qubit estimate assumes a zero bit-flip rate during computation, equating to a century-long bit-flip interval. If the bit-flip frequency increases to once per hour, the required hardware scale for RSA-2048 decryption jumps from 22,593 to approximately 45,000 qubits. These variables remain critical for refining long-term quantum resource projections. ## Current Hardware Development Status Alice & Bob's latest experimental results, released on October 20, involve demonstrators using 12-qubit chips under the French PROQCIMA program. These systems have not yet reached the necessary logical error-correction threshold. The company anticipates that hardware performance gains and reduced resource estimates will converge to make such attacks feasible by the early 2030s. ## Mitigation and Future Standards Developers are actively exploring post-quantum cryptographic defenses to secure the Bitcoin network against these emerging threats. Jameson Lopp and other contributors proposed BIP-361, which outlines a phased approach to freeze quantum-vulnerable legacy addresses. This transition aims to protect long-term holdings before quantum hardware reaches the necessary scale for successful decryption. ## Urgency for Cryptographic Transition The research underscores a narrowing window for organizations to migrate toward post-quantum cryptography. Although the required hardware scale is not yet available, the potential for future decryption necessitates proactive security updates. Stakeholders must prioritize these architectural shifts to ensure the long-term integrity of digital assets against evolving quantum computational capabilities. ## Sources covering this story - https://cryptopotato.com/quantum-says-30000-qubits-could-break-a-bitcoin-key-in-an-hour/ — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._