This demo was originally written as a Perl CGI script for a course taught by Neal Young at Dartmouth College, which is where I studied computer science as a grad student.
I am now a software developer at athenahealth. I have rewritten the demo using PHP. Please email me with any suggestions for improvements. This demo was previously located at Dartmouth and Mercersburg.
Go on to the demo now.
Also read Jamie Ford's more detailed description of quantum cryptography and BB84.