Blockstream names Falcon-1024 its top quantum-resistant signature pick for Bitcoin

Blockstream Research has picked a favorite in the race to quantum-proof Bitcoin. A peer-reviewed paper published on August 6, 2026 names Falcon-1024 as the strongest lattice-based signature candidate for the network.

Picking a favorite is not the same as picking a launch date. The same paper spends considerable time explaining why Falcon-1024 is not ready to drop into Bitcoin anytime soon.

Three contenders, one frontrunner

The paper evaluates three lattice-based post-quantum signature schemes: Dilithium, Falcon, and Hawk. Each was assessed for how well it could work inside Bitcoin’s constraints.

Falcon-1024 won on size. Its combined public key and signature come in at 3,073 bytes.

Dilithium at Category 3 needs 5,261 bytes for the same job. Falcon’s footprint is a bit more than half of Dilithium’s, which matters a great deal on a blockchain where every byte competes for limited block space.

Blockstream also highlighted Falcon-1024’s efficient verification times. Every node on the network checks signatures, so a scheme that verifies quickly keeps the cost of running Bitcoin from ballooning.

The catch list is long

Winning the comparison did not earn Falcon-1024 a clean bill of health. Blockstream laid out several deployment challenges that stand between the scheme and real-world use.

The first is memory. Falcon’s signing process requires about 90 KB, which the report flags as a high demand.

The second issue is implementation complexity. Falcon relies on floating-point arithmetic, the kind of math that works with fractional numbers, and the report notes this makes building it correctly more complicated.

The third problem may hit everyday users hardest. Falcon lacks native support for hierarchical deterministic key derivation.

Finally, Falcon-1024 still needs to reach final standardization. Until that happens, building Bitcoin’s long-term security on top of it would mean committing to a target that could still shift.

The conservative track runs in parallel

The Falcon paper is only part of Blockstream’s quantum work. The company has also been pushing more conservative options, with a focus on hash-based signatures.

Blockstream’s hash-based approach, called SHRINCS, reached draft BIP status in late August 2026. A BIP, or Bitcoin Improvement Proposal, is the formal route for suggesting changes to the protocol, and draft status marks the opening of public review rather than approval.

SHRINCS has already been tested in the wild. Blockstream ran trials on its Liquid sidechain, including a notable post-quantum transaction completed in March 2026.

What this means for Bitcoin

The research points toward a staged transition rather than a single switch. Blockstream frames Falcon-1024 as a strategic long-term option, contingent on standards maturing, not an immediate deployment plan.

For holders and traders, the practical takeaway is that Bitcoin’s current security model stays intact for now. No quantum machine capable of compromising Bitcoin signatures exists today, and nothing in the paper changes that.

Still, the size comparison is a reminder that post-quantum security will not come free. Even the most compact lattice option weighs in at thousands of bytes per key and signature, so any eventual migration will likely force tradeoffs around block space and fees.

Wallet makers have the most homework ahead. The HD derivation gap and the 90 KB signing requirement land squarely on hardware and software wallets, which will need to adapt before any lattice scheme can reach ordinary users.