0ce40265_Class___CodeIgniter_User_Guide__Description
[Preference] encrypt_name [Default Value] FALSE [Options] TRUE/FALSE (boolean) [Description] 
If set to TRUE the file name will be converted to a random encrypted string. This can be useful if you would like the file saved with a name that can not be discerned by the person uploading it.
File Uploading Class : CodeIgniter User Guide
Description