What breaks. What survives.
When a cryptographically-relevant quantum computer arrives, every tool we use today lands in one of four buckets. The asymmetric layer collapses. The symmetric layer mostly holds. The migration path is the right column.
Pre-quantum baseline. Everything looks safe — and most of it is, today.
Broken by Shor's
Completely defeated. Replace.
Weakened by Grover's
Effective key length halves. Upgrade.
Survives with upgrades
Still strong at larger sizes.
Post-quantum replacement
The new foundation.
Back to the source
The shape of the transition
The asymmetric layer — what proves identity and shares keys — has to be rebuilt. The symmetric layer — what protects bulk data — keeps working with bigger keys. PQC is the bridge: ML-KEM picks up where RSA/ECC drop off, ML-DSA picks up where ECDSA drops off, and SLH-DSA stands by as a hash-based backup.
Open the PQC Toolkit