An information processing method has a mechanism wherein mutual verification
is
performed between tasks and a computer operating system at the time of activating
tasks, thereby judging the validity of tasks. The operating system evaluates a
key which the task holds at the time of requesting service of the operating system,
and permits execution of services only in the event that the operating system itself
has the same key.
A mail transmitting task specifies a mail ID and address to a mail body, management
information is written by the operating system to a secure memory queue list based
on the security level of the mail transmitting task and the security level of a
transmitting function, and contents wherein mail transmission contents are enciphered
with the mail ID, address value of management information, and address value of
the mail body, as a key, are written to a buffer. The operating system deciphers
the contents of the buffer wherein the received contents exist, with the mail ID,
address value of management information, and address value of the mail body, as
a key, based on the security level of the mail receiving task and the security
level of a receiving function, and copies this onto a buffer on the mail receiving task.
