Yes, that's how it works, with a per user key. The way it works is that you and your contact will be talking using the same key. The problem is, your contact will somehow need to find out what key you are using in order to talk to you, which makes it kind of pointless. I may decide to make the key used for AutoEncrypt and AutoDecrypt related to the contacts' user ID's, so that you won't need to find out (that actually sounds like quite a good idea
). If you have other ideas, suggest away!
As for the AutoDecrypt, I'll have to see if it is because it is being interfered with another script.
EDIT: Found the problem. It was being interfered by Choli's Linked Chats script.
In the next release, I'll fix the command bug as well. (You can edit the script yourself if you want.
)
PS. Question: If I use multiple messengers (polygamy), do the global variables overlap? Also, anyone know how to make a list of contacts with checkboxes?
EDIT: Updated first post with bug fixes and AutoDecrypt. Now I'll probably get to work on fixing up the whole key thing.
/ 
