Blockstream Identifies Falcon-1024 as Optimal Quantum Shield for Bitcoin

In its third-quarter business update released on November 5, 2026, the Bitcoin infrastructure firm Blockstream detailed its progress in preparing the network for potential future threats from quantum computing. The company’s research team highlighted the necessity of transitioning to post-quantum cryptography (PQC) to safeguard assets against Shor’s algorithm, which could theoretically compromise current ECDSA and Schnorr signature schemes. By evaluating several lattice-based signature technologies, researchers have identified a preferred path for long-term protocol resilience.

Falcon-1024 Identified as the Leading Candidate

The Blockstream team previously published an extensive technical report in August 2026 comparing three primary lattice-based candidates: Dilithium, Falcon, and Hawk. Following a rigorous assessment of on-chain data footprints, verification efficiency, and security maturity, the researchers concluded that Falcon-1024 offers the most effective balance for the Bitcoin blockchain.

• Compactness: Falcon-1024 generates a combined public key and signature size of approximately 3,073 bytes, which is significantly smaller than the 5,261 bytes required by Dilithium at comparable security levels.
• Verification Speed: The scheme features exceptionally fast, integer-only verification, ensuring that full nodes can validate transactions without a significant performance penalty.
• Security Foundations: Unlike Hawk, which was withdrawn following the discovery of a structural flaw by Anthropic researchers, Falcon relies on the more mature NTRU lattice assumptions.

Implementation Challenges and the Short-Term Roadmap

Despite selecting Falcon-1024 as the optimal choice today, Blockstream emphasized that several hurdles remain before a full-scale deployment. The team noted that the FN-DSA standard (the NIST designation for Falcon) is still in the process of finalization. Furthermore, the high memory requirement for signing—approximately 90 KB—presents a significant burden for existing hardware wallets.

"If we had to choose a lattice-based signature scheme for Bitcoin today, we would select Falcon-1024", the researchers stated, while also acknowledging that there is currently no practical solution for BIP-32-style hierarchical deterministic key derivation within this scheme.

In the interim, Blockstream maintains that hash-based signatures, such as their proposed SHRINCS scheme, represent a more conservative and "ready-to-use" option. These could serve as a transitionary layer while lattice-based standards and hardware support mature.

The research underscores that while a cryptographically relevant quantum computer does not yet exist, the long-term nature of Bitcoin as a store of value requires proactive defense strategies. By establishing a roadmap for Falcon-1024 and exploring hybrid signature models, the industry aims to ensure that the Bitcoin network remains secure against the evolution of computing power for decades to come.