C2PA Signer

About

C2PA Signer helps you read, verify, and create Content Credentials (C2PA) directly in your browser — without uploading your files to a server.

Whether you're a journalist, content creator, compliance officer, or simply curious, the extension shows whether a C2PA proof is present on an image, PDF, or video, whether the content matches that proof, and whether the cryptographic signature is valid.

KEY FEATURES

• Verify a local file (JPEG, PNG, PDF, MP4, MOV, WebM)
  Drag and drop a file or use the right-click menu "Verify this image" to get a clear status: C2PA verified, C2PA signed, C2PA invalid, or no C2PA.

• Sign images locally (JPEG / PNG)
  Create a test identity to try signing, or import a professional certificate (.p12 / .pfx). Your keys stay on your device.

• Scan media on a web page
  Detect images and videos on the current tab and view their C2PA status. Manual mode by default; optional automatic scanning with your consent.

• Detailed reports
  Open a readable report with manifest, certificate, trust chain, and sanitized JSON export with sensitive fields removed.

• Advanced settings
  Identity management, allowlists / excluded domains, clearable cache and reports.

PRIVACY & LOCAL PROCESSING

• No backend: verification and signing run locally using the official C2PA SDK (WebAssembly).
• Your identities and certificates are stored locally (Chrome storage + IndexedDB).
• No images are kept permanently on your device.
• Automatic page scanning requires explicit permission; you can exclude sensitive domains.

WHAT THE EXTENSION DOES NOT DO

C2PA Signer does not judge whether content is "true" or "fake." It verifies a cryptographic proof attached to the file. An image without C2PA is not necessarily fraudulent; a signed image may use a test certificate not publicly recognized.

Self-generated certificates (test mode) are for experimentation — they do not prove a public identity. For recognized signatures, import a certificate issued by a certification authority.

PERMISSIONS

• storage, downloads: identities, settings, and signed file downloads
• activeTab, scripting: scan the active page (manual mode)
• contextMenus: verify from the right-click menu on an image
• Site access (optional): only if you enable automatic page scanning

KNOWN LIMITATIONS (v0.1)

• Signing: JPEG and PNG only
• Verification: JPEG, PNG, PDF, MP4, MOV, WebM
• C2PA provenance may be stripped by some platforms when exporting or recompressing content

C2PA Signer is built on Content Authenticity Initiative (CAI) / C2PA standards and embedded trust lists.