zkDaily - 2026-09-05

零知识证明zkDaily

ZKP Frontier Tracker 🎯

Sat

09.05

2026

Delegatable Anonymous Credentials from Legacy Credentials using Recursive zk-SNARKs

Paper

https://eprint.iacr.org/2026/1855

DACPlonky2JWT

Rometsch et al. proposed the first delegatable anonymous credential scheme built on legacy credentials using recursive zk-SNARKs, requiring no issuer changes and offering constant-size credentials with full unlinkability.

NotesNotes要点

First DAC scheme built directly on legacy credentials, with no issuer-side modifications
Credentials remain constant-size regardless of delegation depth, with full unlinkability
Supports selective attribute disclosure at every level of the delegation chain
Instantiated for JWT+ECDSA using Plonky2 as recursive proving backend
Contributes a secure in-circuit JWT parser and a Plonky2 extension for cyclic recursion
Delegation takes 1.2s and verification 3.3ms with 64 attributes

Collected by @icerdesign

零知识证明zkDaily

Q&A Deep Dive 💬

Sat

09.05

2026

Why are legacy credentials incompatible with anonymous credentials?

Legacy credentials use ECDSA and standardized curves, while most anonymous credential schemes rely on pairing-based primitives.

How are constant-size credentials achieved?

Recursive zk-SNARKs aggregate all proofs in the delegation chain into a single constant-size proof.

What vulnerabilities does the in-circuit JWT parser fix?

Parsing occurs inside the zk circuit, fixing vulnerabilities from external parsing in prior work.

Prompted by @icerdesign