HTTP RSA Implementation

Hi, for this week we needed to implement the algorithm rsa in a web service, for the activity I choose php for WS.

The dinamic between server and user is the next:

• The server has e and n, this keys are public.
• The user has n and d, where d is the private key.
• When a user open the page, server generate a x random number.
• The user use this number for generate a response(r), the response is generate for a script, provided for the server.
• Then the user put this r in the service and the server compare r with a num produced.
• If this is correct the users are welcome, else the users are denied.

Important points:

• For generate r (user), need two functions f(x)  &  fastmodexp(x, y, mod).
• where in my case f(x) return (x*2)+5, this can be a other ecuation.
• fasmodexp is f(x)**d mod n
• d is the private key.
• In the autentification for the server we need to implement the same f(x), but this help us  to compare, use fasmodexp(r, e, n), where r is the response of the user and e & n is the public key.

Code:
home.php
rsaAutentification.php
validation.py
Tabla Usuarios

result:

WebService:

You can check the program in the next link: ....

Note:

Php is a pussy,  in my case when I use a big numbers the autentification fail, but checking in python the autentification is correct.