This article was originally written in Japanese and translated using AI. For the original version, please see the Japanese article.
What Is C2PA?
C2PA (Coalition for Content Provenance and Authenticity) is an open technical standard for proving the provenance and authenticity of digital content. It was established in 2021 by a coalition of companies and organizations including Adobe, Microsoft, Intel, Arm, and the BBC.
The C2PA specification provides a mechanism for embedding provenance information into digital content such as photos, videos, audio, and documents. This information records who created or edited the content, when, and how, all in a cryptographically verifiable manner.
This standard emerged from the merger of two earlier projects: the Content Authenticity Initiative (CAI) and Project Origin. CAI, led by Adobe, focused on content authentication in creative tools, while Project Origin, led by the BBC and Microsoft, aimed to ensure the trustworthiness of news media.
Why Is C2PA Necessary?
With the rapid advancement of generative AI, it has become possible to generate not only text but also highly realistic images, videos, and audio. This has ushered in an era where fake content indistinguishable from the real thing can be easily created.
This situation poses serious risks for businesses and media organizations. Damage to brand reputation, social disruption caused by misinformation, and difficulty in proving copyright infringement are just some of the challenges that have emerged.
C2PA provides a technical approach to solving these problems. By making the content creation process transparent and enabling the detection of tampering, it serves as a foundation for ensuring the trustworthiness of digital content.
At TechThanks, we believe that ensuring content authenticity will become a critical theme in corporate activities going forward, which is why we are actively engaged in R&D around C2PA technology.
How C2PA Works Technically
The C2PA technical specification is built around several core concepts.
Manifest
The manifest is the top-level container for information in C2PA. It stores all metadata related to a piece of content. Multiple manifests can be chained together for a single content file, enabling chronological tracking of the creation and editing history.
Assertions
Assertions are data structures that describe individual claims about content. They can include information such as:
- Tools and devices used (e.g., camera model, editing software)
- Types of operations performed (capture, resize, filter application, AI generation, etc.)
- Thumbnails and hash values
- Creator identification information
Digital Signatures
Each manifest is accompanied by a digital signature based on X.509 certificates. This allows cryptographic verification that the manifest contents have not been tampered with, and also confirms the identity of the signer. The signing process uses PKI (Public Key Infrastructure), with trust established through certificate chains issued by Certificate Authorities (CAs).
Metadata Embedding via JUMBF
C2PA metadata is embedded directly within content files using the JUMBF (JPEG Universal Metadata Box Format / ISO 19566-5) container format. JUMBF was originally developed by the JPEG committee as a metadata storage format, but C2PA extends it for use with formats beyond JPEG.
The advantage of this embedding approach is that the metadata and content are unified, so provenance information is preserved even when files are copied or transferred.
Supported Formats
The C2PA specification supports the following media formats:
| Category | Supported Formats |
|---|---|
| Images | JPEG, PNG, WebP, AVIF, HEIF, TIFF, DNG |
| Video | MP4, MOV, WebM |
| Audio | MP3, WAV |
| Documents | |
| 3D | glTF |
The specification defines the embedding location and method for JUMBF metadata for each format. For example, in JPEG files, the JUMBF box is stored in the APP11 marker segment, while PNG files use the caBX chunk.
Implementation Options
Several open-source libraries are available for implementing C2PA.
c2pa-rs (Rust)
This is the reference implementation of the C2PA specification and offers the most comprehensive feature set. Written in Rust, it provides excellent memory safety and performance. It can also be used as a CLI tool for reading and writing manifests from the command line.
# Read a manifest
c2patool <file-path>
# Embed a manifest
c2patool <input-file> -m <manifest-json> -o <output-file>c2pa-node (Node.js)
This is a binding for using C2PA functionality from Node.js applications. Internally, it calls c2pa-rs via WASM or native addons. It is well suited for web application backends and server-side batch processing.
Note that the original c2pa-node has been archived, and migration to its successor c2pa-node v2 is now recommended. Use v2 for any new projects.
c2pa-python
This is a binding available for Python. It is ideal for use cases such as attaching C2PA manifests to data pipeline outputs or AI model outputs.
At TechThanks, we provide implementation support using these libraries. Feel free to contact us about technical challenges such as product integration and workflow design.
Future Outlook
Adoption of C2PA is steadily growing. Major camera manufacturers have begun supporting C2PA at the firmware level, enabling provenance recording from the moment of capture.
On the software side, Adobe Creative Cloud supports C2PA Content Credentials, allowing editing history recording and verification in tools like Photoshop. Social media and news platforms are also progressing in their support for displaying C2PA information.
On the regulatory front, the EU AI Act is being developed with provisions requiring labeling of generative AI outputs, and C2PA is attracting attention as the technical foundation for this requirement.
The effort to technically guarantee the authenticity of content will only grow in importance. C2PA is expected to drive ecosystem-wide adoption as the core standard in this space.