On a LAMP server with bc and bash these web pages
will let a user go through simple examples of the RSA public and private key
process.

The prime numbers used are much smaller than for a normal
RSA key pair, but still have massive intermediate numbers
in the calculations. These web pages also indicate the 
prime number pairs effect on the size of incription key
possible (i.e. the number of bits it uses).
In fact you can try to RSA encrypt values too large
for the keys you have made, and see the erronous results of doing this.

This project was completed (in php4 originally) as part of a module
on web encryption and security
on my MSc in Software Engineering --- Brighton University UK --- way back in 2003.... I thought it was a
good starting point for getting to grips with git-hub (where I had to create 
proper rsa keys from linux, to get it all going).

Robin Clark 08MAR2012