Adult Sites (ADULT_BLIND)

<?php
function getZykayToken(): ?string {
    $partnerId = 'pk_live_yoursite_xxxxxxxx';          // your partner ID
    $secret    = file_get_contents('/path/to/secret'); // your base64 secret
    $body      = json_encode([
        'scopes' => ['isAdult'],
        'origin' => 'https://yoursite.com'             // must match your domain
    ]);
 
    // HMAC signature
    $timestamp = time();
    $nonce     = bin2hex(random_bytes(16));
    $bodyHash  = rtrim(strtr(base64_encode(hash('sha256', $body, true)), '+/', '-_'), '=');
    $canonical = "{$bodyHash}.{$timestamp}.{$partnerId}.{$nonce}";
    $signature = rtrim(strtr(base64_encode(
        hash_hmac('sha256', $canonical, base64_decode($secret), true)
    ), '+/', '-_'), '=');
 
    $ch = curl_init('https://app.zykay.com/api/billing/session');
    curl_setopt_array($ch, [
        CURLOPT_POST           => true,
        CURLOPT_POSTFIELDS     => $body,
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_HTTPHEADER     => [
            'Content-Type: application/json',
            "x-partner-id: {$partnerId}",
            "x-partner-timestamp: {$timestamp}",
            "x-partner-nonce: {$nonce}",
            "x-partner-signature: {$signature}",
        ],
    ]);
    $response = curl_exec($ch);
    $status   = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);
 
    if ($status !== 201) return null;
    $data = json_decode($response, true);
    return $data['token'] ?? null;
}
 
$sessionToken = getZykayToken();
?>

<?php
function verifyAttestation(string $attestation): ?array {
    // 1. Fetch ZYKAY's public key (cache for 1 hour)
    $jwks = json_decode(file_get_contents('https://app.zykay.com/api/billing/attestation-keys'), true);
    $key  = $jwks['keys'][0];
    $publicKey = sodium_base642bin($key['x'], SODIUM_BASE64_VARIANT_URLSAFE_NO_PADDING);
 
    // 2. Split JWS: header.payload.signature
    $parts = explode('.', $attestation);
    if (count($parts) !== 3) return null;
 
    // 3. Verify Ed25519 signature
    $message   = $parts[0] . '.' . $parts[1];
    $signature = sodium_base642bin($parts[2], SODIUM_BASE64_VARIANT_URLSAFE_NO_PADDING);
 
    if (!sodium_crypto_sign_verify_detached($signature, $message, $publicKey)) {
        return null; // invalid signature
    }
 
    // 4. Decode payload
    $payload = json_decode(base64_decode(strtr($parts[1], '-_', '+/')), true);
 
    // 5. Check expiry
    if ($payload['exp'] < time()) return null;
 
    // 6. Check scope (bit 0 = isAdult)
    $isAdult = ($payload['scope_mask'] & 1) === 1;
 
    return [
        'is_adult'   => $isAdult,
        'scope_mask' => $payload['scope_mask'],
        'nullifier'  => $payload['nullifier'],  // unique user ID (privacy-safe)
    ];
}
 
// Usage in your /api/check-age endpoint:
$result = verifyAttestation($_POST['attestation']);
if ($result && $result['is_adult']) {
    $_SESSION['age_verified'] = true;
    echo json_encode(['verified' => true]);
} else {
    echo json_encode(['verified' => false]);
}