Simple PHP/Javascript Capcha System

This system uses a randomly generated, 8 character long, security code. The code is shown as 8 individual images aligned next to each other. Using a jQuery function, the code shows up one character after another until they all show; then it goes away and repeats the same cycle infinitely. Also the code is stored in the browser using the md5 function with php to avoid finding the code in the page source. A simple javascript function verifies the code was entered and entered correctly.