CRYSTALS-Dilithium
CryptographyDefinition
A NIST-standardized (FIPS 204) post-quantum digital signature algorithm based on lattice cryptography over module lattices, selected as the primary post-quantum signature standard for its strong security and performance characteristics.
Technical Details
Dilithium (now ML-DSA under FIPS 204) provides digital signatures replacing RSA and ECDSA for code signing, certificate authorities, and authentication protocols. Its security rests on the hardness of Module Learning With Errors and the Short Integer Solution problem. Three security levels are available (Dilithium2/3/5), with signature sizes ranging from ~2.4KB to ~4.6KB — larger than classical signatures but acceptable for most use cases.
Practical Usage
Certificate authorities and PKI vendors are integrating Dilithium into hybrid certificate formats that combine classical and post-quantum signatures. Code signing infrastructure must be upgraded before quantum computers threaten existing signatures on long-lived software packages and firmware.
Examples
- NIST published FIPS 204 (ML-DSA based on Dilithium) in August 2024 for post-quantum digital signatures.
- A CA pilot program issues X.509 certificates with hybrid RSA + Dilithium signatures for quantum-safe TLS.
- A firmware signing system adds Dilithium signatures alongside existing RSA signatures to future-proof device update authentication.