diff --git a/framework/helpers/base/SecurityHelper.php b/framework/helpers/base/SecurityHelper.php
index 6ba48ba..ed5bfd6 100644
--- a/framework/helpers/base/SecurityHelper.php
+++ b/framework/helpers/base/SecurityHelper.php
@@ -42,7 +42,8 @@ class SecurityHelper
 	public static function encrypt($data, $key)
 	{
 		$module = static::openCryptModule();
-		$key = StringHelper::substr($key, 0, mcrypt_enc_get_key_size($module));
+		// 192-bit (24 bytes) key size
+		$key = StringHelper::substr($key, 0, 24);
 		srand();
 		$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($module), MCRYPT_RAND);
 		mcrypt_generic_init($module, $key, $iv);
@@ -63,7 +64,8 @@ class SecurityHelper
 	public static function decrypt($data, $key)
 	{
 		$module = static::openCryptModule();
-		$key = StringHelper::substr($key, 0, mcrypt_enc_get_key_size($module));
+		// 192-bit (24 bytes) key size
+		$key = StringHelper::substr($key, 0, 24);
 		$ivSize = mcrypt_enc_get_iv_size($module);
 		$iv = StringHelper::substr($data, 0, $ivSize);
 		mcrypt_generic_init($module, $key, $iv);
@@ -148,7 +150,8 @@ class SecurityHelper
 		if (!extension_loaded('mcrypt')) {
 			throw new InvalidConfigException('The mcrypt PHP extension is not installed.');
 		}
-		$module = @mcrypt_module_open('rijndael-256', '', MCRYPT_MODE_CBC, '');
+		// AES uses a 128-bit block size
+		$module = @mcrypt_module_open('rijndael-128', '', 'cbc', '');
 		if ($module === false) {
 			throw new Exception('Failed to initialize the mcrypt module.');
 		}
@@ -269,4 +272,4 @@ class SecurityHelper
 		$salt .= str_replace('+', '.', substr(base64_encode($rand), 0, 22));
 		return $salt;
 	}
-}
\ No newline at end of file
+}