There are essentially two classes of delegation. It is defined
as follows: If an authentication mechanism provides an effective
identity different from the validated identity of the user then
it is called identity delegation at the authentication level,
provided the owner of the effective identity has previously
authorized the owner of the validated identity to use his
identity. The existing techniques of identity delegation using
sudo or su commands of UNIX are very popular. To use sudo
command, a person first has to start his session with his own
original identity. It requires the delegated account password or
explicit authorizations granted by the system administrator. The
user login delegation described in the patent of Mercredi and
Frey is also an identity delegation. The most common way of
ensuring computer security is access control mechanisms provided
by operating systems such as UNIX, Linux, Windows, Mac OS, etc.
If the delegation is fine grained, like Role-based access
control (RBAC) delegation, the