User System on Main Site

[Arrangements]

I've made the hard choice to have my site's user system synchronize with my vb forum users.

I'm creating the registration page right now on my main site; and I've hit a dead end.

I came to this:
$encpass = sha1( SALT . $password );

I'v defined it:
define('SALT', 'something');

So my question of problem is, wouldn't the password be encrypted differently on vb then on my mainsite? How does vb encrypt their passwords?

Edit: Okay after doing some searching, I found this md5(md5($password) . $salt);
to be the way vb hash's up the password. Right? Correct me if I'm wrong.

And then $salt needs needs to pulled from vb's database to check the password on my mainsite.

Now here comes the 2nd part Cookies?

$_COOKIE:
{cookiepfx}userid - plain(userid)
{cookiepfx}password - md5(md5(md5('PlaintextPassword') . salt) . 'LicenseNo').
Why is it does it use md5() 3 times?

Does that mean when I authenticate their cookie information I need to say.. 'reverse the md5()' once and then I can SELECT?

[MoT3rror]

To encrypt the License number so it isn't as easy to get. Also to change the password from what is stored in the database.

[Dismounted]

Why is it does it use md5() 3 times?
So it is more secure.
Does that mean when I authenticate their cookie information I need to say.. 'reverse the md5()' once and then I can SELECT?
You can't reverse MD5. MD5 is a one-way hash. To authenticate the cookie, you will need to encrypt the password from the database to the same algorithm.

[Arrangements]

So it is more secure.

You can't reverse MD5. MD5 is a one-way hash. To authenticate the cookie, you will need to encrypt the password from the database to the same algorithm.

Oh, why didn't I think of that! Thanks, I hear what you are saying.

NOW, this is what has baffled me!

How do I start? <- simple? No?

- How do make a copy of all of the users on the forum onto my main database, while development, when new users have to be created on the forum? Do disable registration while development?
Edit: [Removed because going off topic of the real question]

[Dismounted]

How do make a copy of all of the users on the forum onto my main database, while development, when new users have to be created on the forum? Do disable registration while development?
I'm a bit confused at what you want to do. What you want to do is to convert users, correct? If so, your best option would be to copy some of the users into a test database, then create your conversion script. Test your script on the test database to see if it works correctly, if it does, backup your main database and run your script.