| 摘要 |
A primary key may be used for a first attempt by a remote node to decrypt incoming messages from a master. In the event the decrypt attempt fails at the remote node, a secondary key may then be used to attempt to decrypt the message. Initially, the primary and secondary keys may be the same. A field tool, such as a hand-held programming unit operated by a technician at a remote node location, may change the secondary key, but may not cause any change to the primary key. The secondary key may remain so changed until a new primary key is verified and/or authenticated and the secondary key is overwritten with the new primary key. The primary key may only be changed/set by the master via an encrypted request. A technician may not use a field tool to change a primary key. r --- -------------------------------- 114b 114b 114b 114b 114b Meter Meter Meter Meter 114a Meter i 114a 0 Meter 0 L 114a Meter Meter 114b ~aas",.uuColliector Meter DataCollection r- ----------------- ------- ---- Server 206 0 14b Collector 114a Meter 0 Meter 1a Meter 114a 1- 1114a 100 Meter 14 . 114b 14b Meter_ 0I-~->14 Meter M 14b eMeter Meter Meter 114b Fig. 1 |
