@checkverity/extension

Verity Chrome & Firefox Browser Extension (Manifest V3) — Client-side media authenticity inspector with C2PA and WASM sandbox.

The Verity extension lets users inspect any image or video on the web via right-click context menu or toolbar popup. Analysis runs 100% client-side inside an isolated offscreen WASM document. Raw media is never transmitted to any external server.

Key Features

• 🛡️ C2PA Manifest Inspector: Parses JUMBF boxes and validates x509 cryptographic signing certificates directly in browser WASM.
• ⚡ Local Perceptual Hashing: Computes 64-bit dHash / DCT pHash to detect re-uploaded, cropped, or slightly altered imagery.
• 🔍 Metadata Forensics: Extracts EXIF data, software signatures (e.g. Photoshop, Stable Diffusion tags, Midjourney watermarks).
• 📰 Local OCR (Tesseract.js): Reads text from memes and headlines to search fact-checking databases.
• 🤖 Optional ONNX Classifier: Client-side synthetic media classifier running via WebAssembly (onnxruntime-web).
• 🎨 Neo-Botanical UI: Styled with the Verity design system (Forest Depths, Electric Sprout, Bone White, and custom SVG cursors).

Architecture & Permissions

Offscreen Document Sandbox

Manifest V3 service workers do not have access to the DOM or WebAssembly threads required by @contentauth/c2pa-web, tesseract.js, and onnxruntime-web. Verity routes heavy analytical workloads to an offscreen document (src/offscreen/index.html) communicating over typed Chrome runtime messages.

Permissions Justification

• contextMenus: Adds "Verify with Verity" to image context menus.
• storage: Persists user settings, toggle preferences, and local check counts.
• offscreen: Runs WASM and canvas operations in background execution.
• host_permissions <all_urls>: Allows fetching image bytes for analysis when the user explicitly triggers verification.

Development

# Install dependencies
npm install

# Build extension for production
npm run build -w @checkverity/extension

# Watch mode during development
npm run watch -w @checkverity/extension

# Create packed upload zip for Chrome Web Store
npm run pack
# Output: release/verity-extension.zip

Loading in Google Chrome

1. Open Chrome and navigate to chrome://extensions/.
2. Enable Developer mode in the top right.
3. Click Load unpacked and select packages/extension/dist/.

License

Apache-2.0 © Andrews Mintah