Merge branch 'master_MDL-78698' of https://github.com/mattporritt/moodle

lib/moodlelib.php

@@ -8456,7 +8456,7 @@ function count_letters($string, $format = null) {
  * @return string
  */
 function random_string($length=15) {
-    $randombytes = random_bytes_emulate($length);
+    $randombytes = random_bytes($length);
     $pool  = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
     $pool .= 'abcdefghijklmnopqrstuvwxyz';
     $pool .= '0123456789';
@@ -8485,7 +8485,7 @@ function complex_random_string($length=null) {
     if ($length===null) {
         $length = floor(rand(24, 32));
     }
-    $randombytes = random_bytes_emulate($length);
+    $randombytes = random_bytes($length);
     $string = '';
     for ($i = 0; $i < $length; $i++) {
         $rand = ord($randombytes[$i]);
@@ -8494,48 +8494,6 @@ function complex_random_string($length=null) {
     return $string;
 }
 
-/**
- * Try to generates cryptographically secure pseudo-random bytes.
- *
- * Note this is achieved by fallbacking between:
- *  - PHP 7 random_bytes().
- *  - OpenSSL openssl_random_pseudo_bytes().
- *  - In house random generator getting its entropy from various, hard to guess, pseudo-random sources.
- *
- * @param int $length requested length in bytes
- * @return string binary data
- */
-function random_bytes_emulate($length) {
-    global $CFG;
-    if ($length <= 0) {
-        debugging('Invalid random bytes length', DEBUG_DEVELOPER);
-        return '';
-    }
-    if (function_exists('random_bytes')) {
-        // Use PHP 7 goodness.
-        $hash = @random_bytes($length);
-        if ($hash !== false) {
-            return $hash;
-        }
-    }
-    if (function_exists('openssl_random_pseudo_bytes')) {
-        // If you have the openssl extension enabled.
-        $hash = openssl_random_pseudo_bytes($length);
-        if ($hash !== false) {
-            return $hash;
-        }
-    }
-
-    // Bad luck, there is no reliable random generator, let's just slowly hash some unique stuff that is hard to guess.
-    $staticdata = serialize($CFG) . serialize($_SERVER);
-    $hash = '';
-    do {
-        $hash .= sha1($staticdata . microtime(true) . uniqid('', true), true);
-    } while (strlen($hash) < $length);
-
-    return substr($hash, 0, $length);
-}
-
 /**
  * Given some text (which may contain HTML) and an ideal length,
  * this function truncates the text neatly on a word boundary if possible