Cryptocurrency industry leaders Coinbase and Circle have issued stark warnings about the long-term threat quantum computing poses to the security of Bitcoin and other blockchain networks. According to a detailed analysis by David Duong, Global Head of Investment Research at Coinbase, quantum computers present two specific pathways that could eventually compromise Bitcoin's cryptographic foundations. While the risk is not immediate, investor timelines for quantum readiness are shortening, forcing markets to consider long-dated downside scenarios previously ignored.
Coinbase's analysis centers on a hypothetical "Q-day" when cryptographically relevant quantum computers (CRQCs) could efficiently run Shor's and Grover's algorithms, weakening existing encryption standards. The primary concern is the compromise of transaction signatures, not quantum-accelerated mining. Bitcoin relies on ECDSA for signatures and SHA-256 for proof-of-work. Breaking ECDSA could allow attackers to derive private keys from exposed public keys, enabling unauthorized transfers. Coinbase estimates that 6.51 million BTC, or 32.7% of the total supply, is currently vulnerable to long-range quantum attacks due to address reuse and legacy script types like Pay-to-Public-Key (P2PK) and certain Taproot outputs. Every Bitcoin transaction also faces short-range risk when public keys briefly appear in the mempool during spending.
Circle, the issuer of the USDC stablecoin, echoed these concerns in a separate blog post, noting experts predict quantum computers could compromise blockchain security as early as 2030. The threat from Shor's algorithm directly endangers cryptographic protocols based on elliptic curves (ECDSA) or RSA encryption, impacting transaction signatures, multi-party computations, and some zero-knowledge proofs. However, not all elements are equally vulnerable; hash functions like SHA-256 and symmetric encryption like AES are expected to withstand quantum attacks.
Regulatory pressures are accelerating the need for a transition. Both the United States and the European Union have mandated that critical infrastructure and national security systems migrate to post-quantum cryptography (PQC) by 2030-2035. This timeline aligns with expert estimates of "Q-Day." The discussion has already reached institutional levels, with BlackRock flagging quantum risk in a May 2025 amendment to its iShares Bitcoin Trust (IBIT) prospectus.
Potential solutions and migration paths are being explored. Research groups like Chaincode Labs are evaluating timelines, outlining scenarios ranging from a rapid two-year forced migration to a gradual five-to-seven-year upgrade period. Solutions include quantum-resistant signature schemes like CRYSTALS-Dilithium and SPHINCS+, likely introduced via soft forks. For broader Web3, Circle recommends upgrading every layer of the technology stack, including TLS certificates with hybrid algorithms, exploring stateful signatures like XMSS for Ethereum, and shifting zero-knowledge systems from SNARKs to quantum-safe STARKs. The logistical challenge is significant; Circle cites estimates that migrating all Bitcoin UTXOs could take 76 days of continuous processing.
As Circle's post concludes, "Blockchain designers have the tools they need to transition to post-quantum. It is now a question of will." Delaying could expose trillions in digital assets to risk, but timely upgrades will fortify Web3 for the quantum era.
