Glossary

PQC & QKD, defined.

CBOM

Cryptographic Bill of Materials, a standards-native (CycloneDX 1.6) inventory of every cryptographic asset in an estate.

CRQC

Cryptographically Relevant Quantum Computer, a machine large enough to break RSA/ECC. Its arrival date is the 'z' in Mosca's inequality.

HNDL

Harvest Now, Decrypt Later, capturing encrypted data today to decrypt once a CRQC exists.

Mosca's inequality

If confidentiality lifetime (x) + migration time (y) > time to CRQC (z), you are losing confidentiality on data sent today.

ML-KEM

Module-Lattice Key Encapsulation Mechanism (FIPS 203), the standardised PQC key exchange, formerly Kyber.

ML-DSA

Module-Lattice Digital Signature Algorithm (FIPS 204), standardised PQC signatures, formerly Dilithium.

SLH-DSA

Stateless Hash-based Digital Signature Algorithm (FIPS 205), hash-based signatures, formerly SPHINCS+.

LMS / XMSS

Stateful hash-based signature schemes for long-lived firmware and supply-chain signing; state management is the hard part.

PQC

Post-Quantum Cryptography, algorithms that run on classical hardware but resist quantum attack.

QKD

Quantum Key Distribution, key exchange whose security rests on measurement, not computation; can detect an eavesdropper.

QRNG

Quantum Random Number Generator, entropy from a genuinely quantum source, fixing weak-entropy failure classes.

Hybrid key exchange

Combining a classical (e.g. X25519) and PQC (e.g. ML-KEM-768) key exchange, so the result is safe if either holds.

Crypto-agility

An architecture property: the ability to change algorithms by configuration rather than by rewrite.

Crypto drift

The gradual reintroduction of weak or hard-coded cryptography across releases.