Authenticated mail command processor

Hi,

I am wondering if anyone has written a package for remote command 
processing that has authentication and access control built in.

I am looking for the following:

	1) PGP Authentication of each incoming message
	2) Access control where ability of users to execute commands is
	   finely limited
	3) Protection against replay and MITM attacks, encryption
	4) Sending back of the results of execution
	5) Some form of logging

I need it for my cryptorobomoderator bot, to allow moderators to 
go to vacations and perform other admin tasks w/o logging in.

Thank you.

	- Igor.