A way to generate a custom session ID without editing php.ini

Question

I'm trying to create a custom session ID generator. From what I've read across the sites you can do this by manually editing PHP's settings files, however, it will not be available until I switch from my shared servers to a fully customisable one.

What i'm trying to ask is whether it's possible to specify how session IDs are generated by inputting a PHP code to a page? My intention is to use the same mechanics as the default ID generator, but use sha512 and a few custom goodies such as salt.

Answer 1

If you pass a string to the session_id() function before calling session_start(), you can set the session ID yourself. For example:

function generate_id() {
  ...
  return $your_id;
}

session_id(generate_id());
session_start();