Backward-Compatible Hybrid Post-Quantum Qualified Electronic Signatures: Embedding ML-DSA-65 in PAdES for eIDAS
This work presents an architecture and implementation for hybrid, QES-shaped PAdES that embeds a FIPS 204 ML-DSA-65 signature as an RFC 9882 CMS SignedData counter-signature in the unsignedAttrs of a classical ECDSA-P256 PAdES signature, and maps it to eIDAS 2.0, ETSI and CEN and state its limitations.