Quantum Threat to Bitcoin Not Immediate, Says Blockstream’s Adam Back

• Quantum threat exists, but current hardware cannot execute real attacks on Bitcoin.
• Bitcoin already supports gradual quantum upgrades through Taproot and Schnorr design.
• Blockstream tests post-quantum signatures like SHRINCS on the Liquid protocol.

Concerns about quantum computing breaking crypto security have resurfaced. New research and market debate have pushed the timeline forward, but Blockstream founder Adam Back says the risk is not immediate.

In an interview, he pointed to a gap between theory and real-world capability. Current quantum hardware lacks the scale and error correction needed to break Bitcoin’s cryptography.

Hardware Limits Keep Threat Distant

Recent research, including work referenced by Google, focuses on algorithm improvements. It reduces the estimated resources needed to attack Bitcoin’s ECDLP-256 cryptography.

The requirement has dropped to under 500,000 physical qubits, nearly 20 times lower than earlier estimates. Execution time has also improved, with theoretical attacks possible within Bitcoin’s 10-minute block window.

But the hardware does not exist yet. Back added that current quantum systems are still experimental. They lack proper error correction and stability. Without that, theoretical gains do not translate into real attacks.

He also stated that quantum signature standards were only finalized in November 2024, and the field is still early.

Bitcoin Upgrade Path Already in Place

Back rejects claims that Bitcoin is unprepared. He says the base design already allows gradual upgrades.

Taproot and Schnorr, introduced between 2018 and 2019, were built with future upgrades in mind. Taproot’s structure allows new signature systems to be added without changing the core protocol.

This means Bitcoin can transition without a full overhaul. He also highlighted that research has already validated these designs against quantum scenarios. The system accounts for both short-range and long-range attack models.

Back supports a gradual upgrade path rather than a rushed shift. A phased rollout gives users time to move funds safely.

This includes exchanges, custodians, and long-term holders. Large holders, in particular, move slowly, making coordination a key issue.

A longer timeline reduces the risk of lost funds and incomplete migration. It also allows older systems like ECDSA and Schnorr to be phased out step by step, avoiding sudden disruption.

Testing Already Underway

Development on quantum-resistant systems is already active. Blockstream Research has tested post-quantum signatures like SHRINCS on the Liquid Network. These are hash-based signatures that do not require changes to Bitcoin’s base layer.

Liquid has historically served as a testing ground for upgrades like SegWit and Schnorr before they reached Bitcoin. The same approach is now being used for quantum resistance.

The rollout path starts with simple use cases such as cold storage. More complex systems, including wallets and smart contracts, come later. Key management remains the hardest problem.

Market Split on Urgency

Some analysts argue the threat is overstated and driven by fear. They point out that crypto systems have been preparing for years, with software evolving faster than quantum hardware.

Others see a foundational weakness. Decentralized networks take longer to upgrade than centralized systems. Banks can patch quickly, while blockchains require consensus, creating a timing gap.

Google has set a 2029 target for migration to post-quantum cryptography. Ethereum is already working toward that timeline with active research and test networks.

Bitcoin faces a slower path due to its conservative approach. Estimates suggest 5% to 15% of the Bitcoin supply still sits in quantum-vulnerable addresses. Despite this, incentives remain strong. The network secures over a trillion dollars in value.

Related: Quantum Risk Debate Returns as Crypto Readiness Divides Analysts