Admininstrator Password Portal

Dear coders, I am looking for an experienced developer to construct a wordpress plugin that allows me to control and organise my website logins and grant access to others (Virtual Assistants/Coders/etc) via a master admin panel. Within the master admin area, I will be able to enter URL, usenrame and password. I'll be able to categorise these websites into different groups. There will then be the option to add users such as coders, VA's etc. Selecting their name from a drop list, I'll be able to allocate access to the user to All, one or all groups of sites, or individual sites. I'll be able to give full time access or partial access (that is a time frame of "x" "minutes/hours/days/weeks"). The user will log into a portal with their individually allocated username and password, see a list of websites that are available for them to log into and gain access without knowledge of the "real" site password. This allows me to easily control who has access to my sites without having to manually create, edit or delete users as I hire and fire various people. At this stage, I'm looking for a prototype model. Styling and full features will be applied in stage 2. The site must offer encryption of passwords for protection and must function flawlessly based on the specs I've written above. Comments, suggestions and strategies are welcomed. Regards, Simon