The post-quantum future of web privacy

Cloudflare explains that Privacy Pass, which uses blind signatures to issue unlinkable tokens for abuse prevention, remains unconditionally private but relies on quantum-vulnerable classical cryptography, so quantum attackers could forge tokens. The post explores MOLE (Moderation Of unLinkable Endorsements), a design whose endorsements hide the issuer's identity, and examines post-quantum building blocks including VOLE-in-the-Head proofs, UOV/MAYO multivariate signatures, and the PoMFRIT blind signature (6.7KB, reducible to about 4.3KB with UOV). It also discusses optimizations such as fewer hashes, TurboSHAKE, smaller Keccak states and multivariate commitments, and notes Cloudflare is developing VOLE-IHAT for endorsements and VOLE-ACT for credentials.