exec master..dbd_list_login

This procedure lists information about special logins that have automatic access to encrypted databases. The password column can be 'Yes' or 'No':
Yes -password must exactly match the password specified at setup time.
No - there is no strict password requirement. The access is granted only by the login name.

Example output:

ID    Database      Login        Password  Windows Group
----- ------------- ------------ --------- --------------
1     test1         login1       No        No
2     test1         login2       Yes       No

dbd_list_login is installed in the master database. Items can be added with dbd_add_login and deleted with dbd_del_login.