31. Web Privacy Engineering, Tracking Defenses & Anti-Fingerprinting

// 1. Global Privacy Control (GPC) & Partitioned Cookie (CHIPS) Enforcement
export function evaluatePrivacyHeaders(headers: Headers) {
  const gpcSignal = headers.get('Sec-GPC') === '1';
  const dntSignal = headers.get('DNT') === '1';
  return {
    privacyMode: gpcSignal || dntSignal,
    trackingAuthorized: !gpcSignal,
    // Enforce Partitioned (CHIPS) and Strict storage cookies
    cookieAttributes: [
      'SameSite=Strict',
      'Secure',
      'HttpOnly',
      'Partitioned',
      'Path=/'
    ].join('; ')
  };
}
// 2. Client-Side Anti-Fingerprinting Canvas Noise Injection
export function protectCanvasFingerprint(canvas: HTMLCanvasElement) {
  const ctx = canvas.getContext('2d');
  if (!ctx) return;
  const originalGetImageData = ctx.getImageData.bind(ctx);
  ctx.getImageData = (sx: number, sy: number, sw: number, sh: number) => {
    const imageData = originalGetImageData(sx, sy, sw, sh);
    const data = imageData.data;
    // Micro-jitter pixel values to defeat deterministic hashing
    for (let i = 0; i < data.length; i += 4) {
      data[i] = Math.min(255, Math.max(0, data[i] + (Math.random() < 0.5 ? 1 : -1)));
    }
    return imageData;
  };
}