Post-quantum cryptography for law firms and legal records
Legal work produces some of the longest-lived confidential records in any profession: privileged client communications, sealed settlements, wills that take effect decades after signing, and contracts enforceable for the life of an agreement. Both confidentiality and authenticity must survive that entire span — which puts legal records squarely in scope for harvest-now-decrypt-later, and for the eventual forgeability of classical signatures.
Two distinct guarantees, two distinct risks
Confidentiality (nobody unauthorized can read it) protects privileged communications and depends on key exchange — move that to ML-KEM (FIPS 203) in hybrid mode so archived traffic stays secret. Authenticity (proving who signed and that nothing changed) protects contracts and wills and depends on signatures — a document signed with ECDSA today can be forged once quantum computers exist, so long-lived instruments should carry ML-DSA (Dilithium, FIPS 204) signatures.
Tamper-evident execution records
For contract execution and notarization, sign the document hash together with signer identity and timestamp, and chain entries so any later alteration breaks verification. This gives you a non-repudiable record a court or opposing counsel can check independently, without trusting the firm’s internal systems. Post-quantum signatures keep that record verifiable for the full enforceable life of the agreement.
Honest scope
These techniques prove a document is authentic, unaltered and correctly ordered in time. They do not establish legal validity of the underlying agreement, which remains a question of law, capacity and consent. The cryptography is resistant to known classical and quantum attacks per NIST, not unbreakable. The point is durability: records that outlive the migration window need post-quantum protection now.
Try it yourself — live, free, verifiable in 30 seconds:
Notarize documents with PQC signatures →