function setCookieValidationKey($root, $paths)
{
foreach ($paths as $file) {
echo " generate cookie validation key in {$file}\n";
$file = $root . '/' . $file;
$length = 32;
$bytes = openssl_random_pseudo_bytes($length);
$key = strtr(substr(base64_encode($bytes), 0, $length), '+/=', '_-.');
$content = preg_replace('/(("|\')cookieValidationKey("|\')\\s*=>\\s*)(""|\'\')/', "\\1'{$key}'", file_get_contents($file));
file_put_contents($file, $content);
}
}