Registration passphrase for WordPress similar to JR Passphrase?

Hello all. I am wondering if anyone knows of a plugin or solution for WordPress that would allow us to restrict the ability to register to only those who have a passphrase we provide them. Being able to create multiple (even “unlimited”:wink: would be most desired.

There is an example of what we are looking for called JR Passphrase, but it is for Joomla. We are looking for a WordPress equivalent.

The Joomla one for reference is here:

http://www.rayonics.com/articles/35-joomla/56-jrpassphrase-comparison

http://www.rayonics.com/downloadpage?task=viewcategory&catid=11