[support] Calculating the hashed user password

[Prothero William]

Folks:
I have an external application (a Shockwave movie) that uses my Drupal site for user verification and interaction. I use the store, etc to sell access to my product. My external application accesses the users table to get the username, email, and password. My application compares the entered password with the Drupal password. This was pretty straightforward with Drupal 6, which used MD5 encryption. Now it uses SHA512. While perusing the Drupal 7 scripts, it looks like Drupal relies on the shell to hash the password. 

How can I, with a php script that runs outside of the Drupal environment, calculate the password that Drupal stores? I need this to be able to verify the user and determine the product licenses that he/she has purchased on my Drupal site.

Thanks for any info. I am not a php expert.
Bill

Prothero William
waprothero at gmail.com