Patent ID: 8250095

Claim:
A method for intersystem single sign-on (SSO), the method comprising: obtaining user ID information associated with a first system; in the first system, obtaining the user ID information associated with a second system from the user ID information associated with the first system according to an ID mapping relationship of a user between the first system and the second system, the user ID information associated with the second system being different than the user ID information associated with the first system, the first system and the second system being located in different network domains; in the first system, creating a signature that includes a timestamp and the user ID information associated with the second system before sending the signature to the second system, the creating the signature taking place upon receiving a logon request redirected to the first system by the second system; redirecting the logon request back to the second system upon the creating the signature; sending the signature to the second system to validate the signature by comparing the timestamp of the signature with a timestamp of a previous signature of the user and by comparing the user ID information associated with the second system included in the signature with user ID information stored in the second system, the signature being valid when: a first time indicated by the timestamp of the signature is after a second time indicated by the timestamp of the previous signature of the user, and the first time indicated by the timestamp of the signature is within a predetermined threshold duration of a present time.