Use PHP7's random_bytes() when possible

Close #4260

2 files changed, 21 insertions, 0 deletions

diff --git a/system/core/Security.php b/system/core/Security.php
index 36dea4cf2..e79bf8aff 100644
--- a/system/core/Security.php
+++ b/system/core/Security.php
@@ -593,6 +593,22 @@ class CI_Security {
 			return FALSE;
 		}
 
+		if (function_exists('random_bytes'))
+		{
+			try
+			{
+				// The cast is required to avoid TypeError
+				return random_bytes((int) $length);
+			}
+			catch (Exception $e)
+			{
+				// If random_bytes() can't do the job, we can't either ...
+				// There's no point in using fallbacks.
+				log_message('error', $e->getMessage());
+				return FALSE;
+			}
+		}
+
 		// Unfortunately, none of the following PRNGs is guaranteed to exist ...
 		if (defined('MCRYPT_DEV_URANDOM') && ($output = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM)) !== FALSE)
 		{
diff --git a/system/libraries/Encryption.php b/system/libraries/Encryption.php
index f3e039881..151ce8dec 100644
--- a/system/libraries/Encryption.php
+++ b/system/libraries/Encryption.php
@@ -337,6 +337,11 @@ class CI_Encryption {
 	 */
 	public function create_key($length)
 	{
+		if (function_exists('random_bytes'))
+		{
+			return random_bytes((int) $length);
+		}
+
 		return ($this->_driver === 'mcrypt')
 			? mcrypt_create_iv($length, MCRYPT_DEV_URANDOM)
 			: openssl_random_pseudo_bytes($length);