QUANTUM 09

Quantum-resistant
cryptography

The threat, the new standards, and planning the migration

Sinclair College - Dr. Mike Libassi

TODAY

What we will cover

01The threatHarvest now, decrypt later
02Symmetric cryptoGrover halves key strength
03LatticesLearning with errors
04Standards & migrationWhat to deploy, and when
Quantum 09 · Post-Quantum Crypto2

01 · THE THREAT

Harvest now, decrypt later.

Why the clock is already runningAttackers can record encrypted traffic today and decrypt it once a cryptographically relevant quantum computer exists. Long-lived secrets are already at risk.

02 · SYMMETRIC CRYPTO

Shor breaks it, or Grover weakens it

AlgorithmQuantum attackOutcome
RSA, Diffie-HellmanShorbroken
ECDH, ECDSA, Ed25519Shorbroken
AES-128Grover≈ 64-bit effective security
AES-256Grover≈ 128-bit effective, still strong
SHA-256, SHA-3Groverstill strong at current sizes

The fix for symmetric crypto is simple: use longer keys. CNSA 2.0 requires AES-256.

Quantum 09 · Post-Quantum Crypto4

03 · LATTICES

Learning with errors: easy algebra, plus noise

Without noise

a · s = b (mod q) is solved instantly by elimination.

With noise

a · s + e = b, with small random e, throws the algebra off completely.

At real scale

ML-KEM-768 uses 768 unknowns mod 3329, with no repeating structure for Shor to find.

The noise is added on purpose. Only the holder of the secret key knows enough to strip it back out and recover the message.

Quantum 09 · Post-Quantum Crypto5

04 · THE STANDARDS

NIST's post-quantum toolkit

AlgorithmStandardRoleStatus
ML-KEMFIPS 203key exchange (lattice)final, 2024
ML-DSAFIPS 204signatures (lattice)final, 2024
SLH-DSAFIPS 205signatures (hash-based)final, 2024
FN-DSAFIPS 206compact signatures (Falcon)draft as of mid-2026
HQCin progressbackup key exchange (code-based)selected 2025
Quantum 09 · Post-Quantum Crypto6

04 · WHEN TO START

Mosca's inequality

x+y>z→you're already late
x = years data must stay secret · y = years to migrate · z = years until a CRQC

Example: 10 years of secrecy + 5 years of migration exceeds a 12-year quantum estimate by 3 years.

Quantum 09 · Post-Quantum Crypto7

04 · MIGRATION

How organizations are switching

1

Inventory

Find every use of public-key crypto

›
2

Prioritize

Long-lived data and key exchange first

›
3

Go hybrid

Classical + PQC together, e.g. X25519 + ML-KEM

›
4

Stay agile

Swap algorithms by configuration, not rewrites

NIST's transition plan (IR 8547) proposes deprecating quantum-vulnerable public-key algorithms after 2030 and disallowing them after 2035.

Quantum 09 · Post-Quantum Crypto8

WRAP-UP

Key takeaways

1

Shor breaks RSA and ECC; Grover weakens symmetric keys

2

Harvest now, decrypt later makes key exchange the first priority

3

ML-KEM, ML-DSA, and SLH-DSA are final NIST standards built on hard problems like LWE

4

Migrate with inventory, hybrid deployment, and crypto agility

Quantum 09 · Post-Quantum Crypto9

DISCUSSION

Pick one system you use every day. What would it take to migrate it to post-quantum cryptography?

Consider who controls the software, how long its data must stay secret, and what would break.

Quantum 09 · Quantum-Resistant Cryptography · Questions?  ·  Open the interactive page