Blockstream Identifies Falcon-1024 as Top Post-Quantum Bitcoin Signature Despite Practical Hurdles

Blockstream Research has selected Falcon-1024 as its preferred lattice-based post-quantum signature candidate for Bitcoin, though researchers warn of substantial technical trade-offs. Falcon-1024's combined public key and signature footprint of 3,073 bytes is roughly 42% smaller than rival Dilithium's 5,261 bytes, yet remains about 32 times larger than Bitcoin's current 96-byte Schnorr signatures. The significant size expansion risks reducing effective block capacity and raising transaction fees. Deployment obstacles also include an initial 90 KB signing memory requirement, complex floating-point math, and a lack of hierarchical deterministic wallet support. Bitcoin's existing cryptography remains secure for now.