By WPZARandom File Upload Names Plugin
This plugin from WPZA provides your website randomised file names when you upload files into WordPress.
Randomise file upload names in WordPress
This plugin from WPZA provides your website randomised file names when you upload files into WordPress automatically. Helping with encrypting file names using MD5-encryption, making them harder to be guessed by visitors.
Installation
After installing this plugin, you can start to upload files and it will automatically rename using MD5-encryption in WordPress. Note, this plugin will not rename any pre-uploaded files.