ORIGINPROOF Verifier — Chrome Extension

A Manifest V3 Chrome extension that verifies ORIGINPROOF .oproof sidecar files offline. Drop a file and its .oproof into the popup, get a green/red answer in milliseconds. Zero network requests, zero permissions, zero dependencies — all verification runs locally via the Web Crypto API.

This extension is verify-only. To sign files, use the ORIGINPROOF CLI.

Requirements

• Chrome 120 or later (Ed25519 support in SubtleCrypto)

Load unpacked

1. Open chrome://extensions
2. Toggle Developer mode on (top right)
3. Click Load unpacked
4. Select the originproof-extension/ directory
5. The shield icon appears in your toolbar — click it to open the verifier

Test it

# 1. Build the CLI (if not already built)
cd ../originproof && npm install && npm run build

# 2. Sign any file
npx originproof sign README.md

# 3. In Chrome, click the extension icon, drop README.md and README.md.oproof
# Expected: green "VERIFIED" with signer metadata

File structure

originproof-extension/
├── manifest.json              MV3 config, zero permissions
├── popup/
│   ├── popup.html             Two drop zones + verify button + result + footer
│   ├── popup.css              Dark theme with indigo accent
│   ├── popup.js               DOM, drag-drop, BOM handling, result rendering
│   └── verify.js              Pure verification logic (Web Crypto port)
├── icons/                     Shield icon at 16/48/128
├── docs/
│   └── popup-verified.png     Screenshot captured by tests/e2e/screenshot.mjs
└── tests/
    ├── verify.test.mjs        10 logic scenarios via node:test
    ├── popup.test.mjs         10 DOM-layer scenarios via jsdom
    ├── generate-fixture.mjs   Pretest hook — signs sample.txt in-process
    ├── fixtures/sample.txt    Stable committed sample for signing
    └── e2e/
        ├── server.mjs         Static server for HTTP-served popup
        ├── popup.e2e.mjs      5 end-to-end scenarios in real Chromium
        └── screenshot.mjs     Playwright script that captures the README PNG

Verification statuses

Status	Meaning	Color
VERIFIED	File is authentic and unmodified	green
HASH_MISMATCH	File has been modified since signing	red
INVALID_SIGNATURE	Signature doesn't match the embedded public key	red
MALFORMED_PROOF	Proof is missing, corrupt, or has an unsupported version	yellow
UNSUPPORTED_BROWSER	Chrome version too old — upgrade to 120+	yellow
FILE_TOO_LARGE	File exceeds 250 MB limit	yellow
FILE_EMPTY	File buffer has zero length	yellow

Tests

There are two test tiers:

Unit + DOM tests (fast, no browser)

npm test

Runs 20 tests via node:test:

• verify.js (10) — pure logic loaded via new Function wrapper: happy path, tamper detection, corrupted signature, garbage JSON, missing fields, extra-field resilience, version mismatch, uppercase hex, empty file, UTF-8 BOM stripping.
• popup.js (10) — DOM layer via jsdom: initial render, button enablement, file-drop input, dataTransfer drops, drag-over visual feedback, XSS escaping in error messages, full verify click flow, BOM stripping at the I/O boundary, FILE_EMPTY flow, and version footer population.

The pretest hook signs tests/fixtures/sample.txt in-process using Node's built-in crypto. It caches by content hash — if sample.txt hasn't changed since the last run, signing is skipped. No CLI dependency.

End-to-end tests (real Chromium via Playwright)

npm run test:e2e

Runs 5 scenarios in headless Chromium 147 against an HTTP-served popup: version footer populates, VERIFIED round-trip, HASH_MISMATCH on tampered file, INVALID_SIGNATURE on flipped signature byte, MALFORMED_PROOF on garbage JSON. Catches any Chrome-vs-Node behavioral drift that jsdom + Node's crypto.subtle would miss.

First run downloads ~92 MB of Chromium Headless Shell via npx playwright install chromium.

Updating the README screenshot

npm run screenshot

Drives the real popup through a verification flow in Chromium and writes docs/popup-verified.png. Every pixel is produced by real verification code — no DOM injection. Rerun after visual changes.

What this extension does not do

• No signing. Use the CLI.
• No page scanning. The extension does not auto-detect .oproof files on websites.
• No network requests. Fully offline.
• No background activity. No service worker, no persistent state.

.oproof format

See the main ORIGINPROOF README for the full JSON schema.