TL;DR

Privacy Pass is a protocol that lets a site issue a client unlinkable tokens, so an operator can rate-limit traffic without tracking the person behind each request.

Cloudflare has run Privacy Pass in production for 10 years and published on 6 November 2026 a design study for its post-quantum successor, under the working name MOLE.

Today's tokens use RSA and elliptic-curve blind signatures. A cryptographically relevant quantum computer could forge them.

MOLE adds an endorsement issued by an anchor and redeemed by a moderator, and the client proves possession of an endorsement issued by one anchor in the agreed set without revealing which anchor issued it.

The construction comes from VOLE-in-the-Head, a proof system that a prover can turn into a signature, and the PoMFRIT blind signature built on it shrinks to 4.3KB when UOV replaces MAYO.

Cloudflare estimates 5.6KB of issuance for VOLE-IHAT and 5.4KB for VOLE-ACT, with 6.5KB and 12.0KB at redemption, against 46.6KB public keys.

The costs and the…