@checkverity/core

Pure TypeScript multi-signal media authenticity engine, C2PA manifest evaluator, perceptual hash BK-tree index, and forensic fusion core.

@checkverity/core is the platform-agnostic analytical engine behind Verity. It contains zero DOM or Node-specific dependencies, running identically in browsers, Chrome Extension offscreen WASM workers, Node.js services, Cloudflare Workers, and serverless environments.

The Verity Philosophy: "What can we verify?"

Traditional AI detectors attempt to answer "is this fake?" with fragile statistical models that frequently misclassify authentic smartphone photos as synthetic.

@checkverity/core reframes verification into evidence fusion:

• ✅ verified: Cryptographically signed provenance confirmed (valid C2PA x509 certificate chain).
• ❓ unverified: Insufficient provenance found. This is the natural baseline for most internet media — it does not imply the content is false.
• ⚠️ suspicious: Direct counter-evidence identified (tampered C2PA manifest, prior sightings under contradictory context, or debunked fact-checks).

Signal Architecture

| Signal | Source | Role | | :--- | :--- | :--- | | c2pa | @contentauth/c2pa-web / c2pa-node | Validates signed provenance manifests and x509 certificate chains. | | forensics | exifr | Camera EXIF, editing software history, GPS metadata, and AI-generator tags. | | phash | 64-bit dHash / DCT pHash | Perceptual fingerprinting robust to crops, scaling, and compression. | | bktree | Built-in Metric Tree | O(log N) nearest-neighbor search for perceptual near-duplicates. | | factCheck | Google Fact Check Tools / ClaimReview | Newsroom debunks and journalist fact-check matches. | | daylight | suncalc | Validates sun position against EXIF GPS and timestamp. | | weather | Open-Meteo Archive | Cross-checks claimed weather against historical meteorological records. | | domainAge | RDAP protocol | Evaluates publisher domain registration age. |

Installation

npm install @checkverity/core

Usage Example

import { fuseSignals, computeHammingDistance, BKTree } from '@checkverity/core';
import type { SignalResult, Verdict } from '@checkverity/core';

// 1. Collect signals from available analyzers
const signals: SignalResult[] = [
  {
    type: 'c2pa',
    status: 'unsupported',
    summary: 'No C2PA manifest found in image container'
  },
  {
    type: 'forensics',
    status: 'positive',
    summary: 'Sony ILCE-7M4 camera metadata verified; Lightroom edit history consistent'
  }
];

// 2. Compute the multi-signal verdict
const verdict: Verdict = fuseSignals(signals);

console.log(verdict.state);    // 'unverified'
console.log(verdict.headline); // 'No cryptographic provenance found. Baseline state for web media.'

Perceptual Hash BK-Tree

Fast near-duplicate retrieval with metric distance bounds:

import { BKTree } from '@checkverity/core';

const tree = new BKTree();

// Add 16-character hex perceptual hashes
tree.add('d3c2a1b4e5f60718', 'sha256_record_1');
tree.add('d3c2a1b4e5f60719', 'sha256_record_2');

// Find all matches within Hamming distance <= 4
const matches = tree.search('d3c2a1b4e5f60718', 4);
console.log(matches);

License

Apache-2.0 © Andrews Mintah