Ledger CTO: Post-Quantum Crypto Migration Enters Pivotal Phase, Blockchain Leans Towards Hash-Based Signature Scheme

April 23 — Ledger CTO Charles Guillemet noted in a blog post that post-quantum cryptography (PQC) is entering a critical phase. While the timeline for quantum computers capable of breaking current cryptographic systems remains uncertain, the industry widely agrees a shift to PQC is inevitable. The traditional sector has a clear roadmap, led by the U.S. National Institute of Standards and Technology (NIST): phasing out vulnerable legacy algorithms by 2030, with full disablement by 2035. Large enterprises and government agencies are accelerating preparations to complete the transition by 2029. On the technical front, encryption and key exchange will transition to ML-KEM (formerly CRYSTALS-Kyber) to counter “decrypt-then-collect” quantum attacks. But in the blockchain ecosystem, the core focus is digital signatures. Current mainstream PQC signature schemes fall into two categories: lattice-based ML-DSA (formerly CRYSTALS-Dilithium) and hash-based SLH-DSA (formerly SPHINCS+). The traditional industry leans toward ML-DSA and hybrid schemes with elliptic curve cryptography (ECC), while the blockchain sector favors hash-based signatures for their security conservatism and structural simplicity. Each scheme has trade-offs: ML-DSA delivers better performance but its security assumptions haven’t been long-term validated; SLH-DSA, while less efficient, relies on mature hash functions, making its security more deterministic. For blockchains prioritizing long-term security and validation paths, the latter is more appealing. However, regardless of the chosen scheme, compatibility with Multi-Party Computation (MPC) and Threshold Signatures remains an unresolved challenge — a risk particularly critical for industries relying on custodial and collaborative signatures.