Ledger CTO breaks down NIST’s post-quantum signatures and what they mean for Bitcoin and Ethereum

Quantum computing is still mostly a theoretical threat to crypto wallets. But the cryptography community isn’t waiting around to find out exactly when “theoretical” becomes “Tuesday.” NIST published its first finalized post-quantum cryptography standards in August 2024, and Ledger CTO Charles Guillemet has been walking through what those standards actually mean for Bitcoin, Ethereum, and the hardware security world his company operates in. Two standards, two philosophies NIST’s August 2024 announcement formalized two digital signature schemes that matter most here. The first is ML-DSA, published as FIPS 204 and based on the CRYSTALS-Dilithium algorithm. It’s a lattice-based approach, meaning its security relies on the computational hardness of certain geometric problems in high-dimensional space. The second is SLH-DSA, published as FIPS 205 and built on Sphincs+. This one takes a more conservative route: its security is grounded entirely in hash functions, the same cryptographic primitives that have been battle-tested for decades across computing. No novel mathematical assumptions required. The tradeoff is that Sphincs+ produces larger signatures, which matters a lot when you’re pa...