Check C2PA Tool and prepare the sample image

Create a working directory

Use bash or zsh on Linux or macOS, or PowerShell on Windows.

Open your terminal in the directory where you keep your projects, then create and enter a working directory:

    

        
        
mkdir c2pa-demo
cd c2pa-demo

    

These commands create the c2pa-demo folder and make it the working directory of your terminal. If the folder already exists, run only cd c2pa-demo. Run the remaining commands from this directory. Keep all files from this Learning Path in the same folder. That way, the commands can use filenames without full paths.

Confirm C2PA Tool is available

Ensure that you’ve installed the Coalition for Content Provenance and Authenticity (C2PA) Tool. For instructions, see the C2PA Tool install guide .

Run the platform-independent version check:

    

        
        
c2patool --version

    

The version number depends on the current stable release. All subsequent outputs in this Learning Path were recorded using c2patool version 0.27.21.

Download the sample image

In a real-world workflow, the software that creates or modifies a digital asset adds Content Credentials as part of that process. For example, when you take a photograph with a camera that supports Content Credentials, the camera software signs the image. It adds Content Credentials during capture.

To focus on signing and validation without setting up a camera, you can use a sample JPEG. For a sample JPEG, refer to the Content Authenticity Initiative contentauth/c2patool repository , pinned to v0.27.20.

Assume that the sample represents a digitally captured photograph. The capture details are available to the camera software when it adds Content Credentials.

From your c2pa-demo working directory, download the sample JPEG as image.jpg using wget:

    

        
        
wget -O image.jpg https://raw.githubusercontent.com/contentauth/c2patool/v0.27.20/sample/image.jpg

    

The command saves the JPEG as image.jpg, replacing that file if it already exists. The URL points to the raw image rather than the GitHub HTML page. The file is 61,720 bytes. Keep this unsigned source file for the later steps.

The upstream sample is provided under the MIT license, © Copyright 2020 Adobe . Retain its copyright and permission notice if you redistribute the image.

Confirm the starting state

Use C2PA Tool to confirm that the source image doesn’t already contain a manifest:

    

        
        
c2patool image.jpg --info

    

The expected output is:

    

        
        No C2PA Manifests. (file size = 61720)

        
    

The downloaded sample has no existing C2PA manifest, so you can use it as the unsigned source later.

What you’ve accomplished and what’s next

You’ve set up the C2PA Tool and downloaded a sample JPEG image from GitHub. You’ve also confirmed that the image has no existing C2PA manifest.

Next, you’ll add Content Credentials to the sample image.