The present invention includes a client computer, a first server computer,
and a second server computer. The first server provides an authorization
ticket containing a time stamp to the client computer when the client
computer is authorized to access the first server. An elapsed time
counter is started at the client computer when access is provided to the
first server. When a request is received at the client computer to access
the second server, the client computer determines the session length
based upon the elapsed time counter. The client computer calculates a
hash value for the authorization ticket, the session length, and a secret
shared with the second server computer. The client computer transmits a
login request to the second server including the authorization ticket,
the session length, and the hash. The second server decrypts the
authorization ticket and retrieves a copy of the shared secret. The
second server executes a hash function on the authorization ticket, the
session length, and the shared secret. The second server then compares
the computed hash to the hash value received from the second client
application. If the two hash values are identical, the second server
retrieves the time stamp from the authorization ticket and adds the
session length to the time stamp. The second server then compares the
resulting value to the current time. If the resulting value and the
current time are within a preset threshold value, the client computer is
provided.