Blockstream is studying how Bitcoin could adopt new digital signature schemes to guard the network against potential threats from future quantum computers, and its research team has identified Falcon-1024 as the leading lattice-based candidate after weighing several alternatives.

According to Wu Blockchain, researchers at the Bitcoin infrastructure firm assessed Dilithium, Falcon and Hawk as candidate lattice-based signature schemes. Lattice-based cryptography is among the most widely studied families of post-quantum algorithms, resting on mathematical problems believed to remain hard even for quantum computers. Their comparison came down in favor of Falcon-1024, which the team viewed as a suitable balance of compact signatures, fast verification and mature security assumptions.

Why Falcon-1024 Stood Out

The evaluation forms part of ongoing research into cryptographic approaches that could help Bitcoin address risks stemming from advances in quantum computing. Bitcoin currently secures transactions with elliptic-curve signatures, and a sufficiently powerful quantum computer running Shor's algorithm could in principle break the mathematics behind them, which is why signature schemes sit at the center of the network's quantum-readiness discussions. Digital signatures are foundational to Bitcoin's security model, and the prospect of future quantum capabilities has prompted researchers to examine alternatives to the cryptographic methods currently in use.

Of the three lattice-based options considered, Falcon-1024 distinguished itself through a combination of practical performance characteristics and security considerations. Its compact signature sizes and fast verification were among the factors supporting the team's preference.

However, identifying a promising candidate does not mean the technology is ready to be deployed across Bitcoin. According to the research summary, several technical and implementation challenges remain unresolved.

Standardization and Wallet Hurdles

One obstacle is unfinished standardization. Without completed standards, integrating a new signature scheme into Bitcoin would require further technical work and evaluation, even as post-quantum algorithms more broadly have been through multi-year vetting efforts such as the one led by the U.S. National Institute of Standards and Technology. The researchers also highlighted the memory requirements of hardware wallets, which could complicate implementation on devices with limited resources.

A further unresolved issue is the absence of a workable public-key derivation scheme. This presents an additional hurdle for adapting lattice-based signatures to Bitcoin's existing key-management arrangements.

Blockstream's research therefore draws a distinction between evaluating a potential long-term solution and selecting an approach that could be implemented in the near term.

Hash-Based Signatures Remain the Conservative Path

Despite the interest in lattice-based cryptography, the researchers emphasized that hash-based signatures remain the more conservative near-term option for Bitcoin. Hash-based schemes draw their security from hash functions rather than from the elliptic-curve mathematics most exposed to quantum attacks, which is why they are often treated as the conservative choice in post-quantum planning. That framing positions Falcon-1024 as a candidate under consideration rather than an immediate replacement for the network's existing signature system.

A hybrid deployment could also emerge as a potential future approach, allowing different cryptographic methods to be incorporated together. However, the research summary does not establish a deployment schedule, nor does it confirm that Bitcoin will adopt Falcon-1024.

For now, Blockstream's evaluation underscores both the promise of lattice-based signatures and the practical work that still lies ahead, including standardization, hardware wallet compatibility and public-key derivation.