This is an academic example of the diffie-hellman key exchange in PHP. It is not meant to be used for any real world purpose. The values of $p; $g; $a; $b are generated randomly as per the Diffie-Hellman protocol.
This library requires PHP >= 7.x and the GNU Multiple Precision/GMP functions enabled in PHP's Mathematical Extensions (http://php.net/manual/en/book.gmp.php)
without this it will NOT work. This application is meant to handle very large integers, tested as high as 3072 bits.
Application can be run from anywhere. On windows, you can just put it in the same folder as your PHP binary.
Run via terminal. The program takes the size of the prime number p in the specified bit range.
Command:
php ./diffie-hellman.php 32
Output:
The value of p selected: 2205759217
The value of g selected: 2000375980
The value of a selected by Alice: 2016295672
The value of b selected by Bob: 1146783380
The value of A sent to Bob by Alice: 591592312
The value of B sent to Bob by Alice: 287287597
Shared Key: 218785632
This is free and unencumbered software released into the public domain for educational purposes.