Paper 2026/804

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

Abstract

Generative AI and advanced editing tools enable malicious actors to create high-quality fake images that can propagate fraud, attack reputations, and manipulate elections. We analyze security properties of the Coalition for Content Provenance and Authenticity (C2PA) digital provenance system, which binds cryptographic assertions of provenance to a digital asset, helping users judge its origin. We analyze three C2PA components: specifications (Version 2.2), selected claim validator implementations, and conformance program (Version 0.1). We state C2PA's security goals (tamper-evidence of claims and weak file integrity), identify essential additional goals (timestamp agreement, validator consistency, and strong file integrity), review major policies, examine composition with RFC 3161 trusted timestamps, and carry out the first formal-methods analysis of the core protocols. We show that the specifications and conforming implementations fail to achieve both claimed and essential security goals. Our formal-methods analysis reveals that generators and validators fail to agree on the signature's trusted timestamp, enabling timestamp alterations that cast doubt on provenance. Inadequate certificate revocation policies cause conforming validators to accept manifests signed with known-compromised certificates, violating all security goals. Conforming validators produce inconsistent results; the exclusion range enables undetectable alterations; and the conformance program certifies products without technical review or defined requirements. Our results show that C2PA does not yet provide the guarantees required for reliable deployment. We suggest concrete improvements, some of which were adopted in the Pixel 10 Pro and C2PA Version 2.3.