Blockstream Selects Falcon-1024 as Leading Quantum-Resistant Signature for Bitcoin
Blockstream Research has named Falcon-1024 as the leading candidate for quantum-resistant signatures in Bitcoin, according to a peer-reviewed paper published on August 6, 2026. This selection highlights the ongoing efforts to secure Bitcoin against potential quantum computing threats.
Evaluation of Candidates
The paper evaluated three lattice-based post-quantum signature schemes: Dilithium, Falcon, and Hawk. Falcon-1024 emerged as the frontrunner due to its smaller size, with a combined public key and signature of 3,073 bytes, significantly less than Dilithium's 5,261 bytes. This compact size is crucial for blockchain efficiency, where every byte counts.
Challenges Ahead
Despite its advantages, Falcon-1024 faces several challenges before it can be implemented in Bitcoin. Key issues include:
- Memory Requirements: The signing process for Falcon requires about 90 KB of memory, which is considered high.
- Implementation Complexity: The reliance on floating-point arithmetic complicates the implementation process.
- Lack of Support: Falcon does not support hierarchical deterministic key derivation, which is essential for many wallet applications.
- Standardization: Falcon-1024 still needs to undergo final standardization before it can be adopted.
Alternative Approaches
Alongside Falcon-1024, Blockstream is exploring more conservative options, such as hash-based signatures, with its SHRINCS proposal reaching draft BIP status in late August 2026. This approach aims to provide a more immediate solution while the community evaluates Falcon-1024.
Implications for Bitcoin Users
The research indicates a gradual transition to quantum-resistant technologies rather than an immediate overhaul. For Bitcoin holders, the current security model remains intact, as no quantum computers capable of compromising Bitcoin signatures exist today. However, the eventual migration to post-quantum security will require careful consideration of block space and transaction fees.
FAQ
What is Falcon-1024 and why was it selected by Blockstream?
Falcon-1024 is a quantum-resistant signature scheme that Blockstream Research has identified as the leading candidate for securing Bitcoin against potential quantum computing threats. It was selected due to its smaller size compared to other candidates, which is crucial for blockchain efficiency.
What are the main advantages of Falcon-1024 over other signature schemes?
The primary advantage of Falcon-1024 is its compact size, with a combined public key and signature of 3,073 bytes, significantly smaller than Dilithium's 5,261 bytes. This smaller size helps improve blockchain efficiency, where every byte is important.
What challenges does Falcon-1024 face before implementation in Bitcoin?
Falcon-1024 faces several challenges, including high memory requirements for signing (about 90 KB), implementation complexity due to reliance on floating-point arithmetic, lack of support for hierarchical deterministic key derivation, and the need for final standardization.
Are there alternative approaches being considered alongside Falcon-1024?
Yes, Blockstream is also exploring more conservative options, such as hash-based signatures. The SHRINCS proposal has reached draft BIP status and aims to provide a more immediate solution while the community evaluates Falcon-1024.
What does the research imply for Bitcoin users regarding quantum security?
The research suggests a gradual transition to quantum-resistant technologies rather than an immediate overhaul. Currently, the security model for Bitcoin remains intact, as no quantum computers capable of compromising Bitcoin signatures exist today. However, future migration to post-quantum security will need careful consideration of block space and transaction fees.
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