Move random Digits to Crypto class

src/Core/System.php

@@ -265,7 +265,6 @@ class System extends BaseObject
 	function notice($s)
 	function info($s)
 	function is_site_admin()
-	function random_digits($digits)
 	function get_server()
 	function get_temppath()
 	function get_cachefile($file, $writemode = true)

src/Object/Post.php

@@ -18,6 +18,7 @@ use Friendica\Database\DBA;
 use Friendica\Model\Contact;
 use Friendica\Model\Item;
 use Friendica\Model\Term;
+use Friendica\Util\Crypto;
 use Friendica\Util\DateTimeFormat;
 use Friendica\Util\Proxy as ProxyUtils;
 use Friendica\Util\Temporal;
@@ -815,7 +816,7 @@ class Post extends BaseObject
 				'$indent'      => $indent,
 				'$sourceapp'   => L10n::t($a->sourcename),
 				'$ww'          => $conv->getMode() === 'network' ? $ww : '',
-				'$rand_num'    => random_digits(12)
+				'$rand_num'    => Crypto::randomDigits(12)
 			]);
 		}
 

src/Util/Crypto.php

@@ -476,4 +476,30 @@ class Crypto
 
 		return self::decryptAES256CBC(base64url_decode($data['data']), $k, $i);
 	}
+
+
+	/**
+	 * Creates cryptographic secure random digits
+	 *
+	 * @param string $digits The count of digits
+	 * @return int The random Digits
+	 */
+	public static function randomDigits($digits)
+	{
+		$rn = '';
+
+		if (!function_exists('random_int')) {
+			// using rand() function for PHP 5.x compatibility
+			for ($i = 0; $i < $digits; $i++) {
+				$rn .= rand(0, 9);
+			}
+		} else {
+			// generating cryptographically secure pseudo-random integers
+			for ($i = 0; $i < $digits; $i++) {
+				$rn .= random_int(0, 9);
+			}
+		}
+
+		return $rn;
+	}
 }