What is post-quantum cryptography?

Post-quantum cryptography is cryptography built to stay secure against quantum computers, which could break the elliptic curves and RSA that most wallets and websites rely on today.

Also called quantum-safe cryptography, quantum-resistant cryptography or PQC.

What a quantum computer would break

Shor’s algorithm would let a large quantum computer recover a private key from its public key, for elliptic-curve signatures such as ECDSA and Schnorr and for RSA alike. Hash functions only lose part of their margin, so cryptography built on hashes stays standing.

The new standards

In August 2024 NIST published its first three post-quantum standards. FIPS 203 (ML-KEM) and FIPS 204 (ML-DSA) are built on lattices, and FIPS 205 (SLH-DSA) is built on hash functions alone.

Hashes or lattices

Lattice schemes are smaller and faster, and they rest on newer mathematical assumptions. Justin Drake has argued for going all in on hash-based cryptography and avoiding structured assumptions from curves, lattices and isogenies alike.

In Redacted

Redacted’s bunker mode uses hash-based building blocks only, with SHA-256 for notes and proofs, STARKs that need no trusted setup and SLH-DSA for signatures. It uses no curves and no lattices.

Bunker mode →

Related terms

Hash functionA hash function turns any input into a short fingerprint of fixed size. The same input always gives the same fingerprint, and nobody can work back from it or find two inputs that share one.SLH-DSASLH-DSA is the hash-based signature standard NIST published in 2024 as FIPS 205. It is based on SPHINCS+, and its security rests only on hash functions.STARKA STARK is a zero-knowledge proof built from hash functions alone. It needs no trusted setup and no elliptic curves, so it is expected to hold up against quantum computers.ECDSAECDSA is the elliptic-curve signature scheme behind most Bitcoin and Ethereum wallets. It proves you hold a private key without showing it, and its security rests on the math of the secp256k1 curve.Bunker modeBunker mode is Justin Drake’s name for a calm, controlled move of crypto to addresses whose public keys are still hidden behind a hash, in case elliptic curves break sooner than expected.

Sources: NIST releases first 3 finalized post-quantum encryption standards, August 2024

Updated October 12, 2026. All terms