zkDaily - 2026-04-28

零知识证明 zkDaily

ZKP Frontier Tracker 🎯

Tue

04.28

2026

Verifying Provenance of Digital Media: Security Analysis of C2PA and its Implementation

Paper

https://eprint.iacr.org/2026/804

Neal Krawetz C2PA security analysis

Krawetz et al. conducted a security analysis of the C2PA digital provenance system, finding that its specifications and implementations fail to achieve claimed security goals, including timestamp disagreement, certificate revocation vulnerabilities, and validator inconsistencies.

Notes

C2PA specs fail to meet claimed tamper-evidence and weak file integrity goals.
Formal analysis shows disagreement on trusted timestamps between claim generators and validators.
Inadequate certificate revocation allows known compromised Nikon certificates to be accepted.
Validator inconsistencies lead to contradictory conclusions for the same asset.
Exclusion ranges in spec permit undetectable alterations.
Conformance program lacks technical review; improvements suggested for timestamping.

Collected by @icerdesign

零知识证明 zkDaily

Q&A Deep Dive 💬

Tue

04.28

2026

What is the main goal of C2PA?

C2PA aims to provide provenance for digital media by attaching signed metadata that records how content was created and modified, helping users assess authenticity.

What issue does the paper find with timestamps in C2PA?

Generators and validators may disagree on timestamps, allowing conflicting timestamps for the same content, which undermines trust in provenance.

Why does the paper argue that C2PA is not ready for reliable deployment?

Because of issues like timestamp inconsistency, weak revocation, inconsistent validator behavior, and unprotected regions, all of which undermine reliable provenance verification.

Prompted by @icerdesign