INTRODUCTION TO TID
The Token Identifier is a 24-bit field, contained in STS compliant tokens, that identifies the date and time of the token generation. It is used to determine if a token has already been used in a payment meter. The TID represents the number of minutes elapsed since the base date of 1st January 1993. The incrementing of the 24-bit field means that at some point in time, the TID value will roll over to a zero value.
All STS prepayment meters will be affected by TID roll over on the 24/11/2024. Any tokens generated after this date and utilizing the 24-bit TID, calculated on base date 1993, will be rejected by the meters as being old tokens as the TID value encoded in the token will have reset back to 0.
In order to overcome the TID rollover occurrence, all meters will require key change tokens with the roll over bit set. In addition to this, the base date of 01/01/1993 will be required to be changed to a base date of 01/01/2014. This process will force the meters to reset the TID stack memory to 0. To avoid previously used tokens from being accepted by the meter due to the TID stack reset, the key change process changes the meter key at the same time.
A process is therefore required to allow for the management of this TID Rollover key change with the least impact to the utilities and equipment suppliers.