a version number is associated with an encrypted key executable to allow real time updating of keys for a system which facilitates users signing on to multiple websites on different domains using an encrypted ticket . two keys may be used at each site during updating of keys , each having an associated one digit hex version tag . when a key is to be updated with a new key , the existing or old key is provided an expiration time . a second key is provided from the system in a secure manner with a new version number and made the current key which provides decryption of the encrypted ticket . the system tracks both keys while they are concurrent . after the existing key expires , only the second , or updated key is used to provide login services for users . the system periodically flushes old keys .