Aclara SGM1400 Series, User Manual

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S G M 1 4 0 0 S e r i e s S m a r t M e t e r U s e r M a n u a l – S M E T S 2
Prepayment Solution
Prepayment Key
The secret 128-bit prepayment key used in the MAC generation and UTRN
validation is written to the ESME under the control of the headend system when
the Update Security Credentials command is sent.
Upon a successful execution of this command, the ESME will reset its internal
UTRN counter cache.
UTRN Counter Cache
The ESME holds and maintains a UTRN counter cache to prevent ‘replay’ of
previously processed UTRNs. The UTRN counter cache can hold 100 processed
UTRNs (first in, first out order) and contains entries of the 32 most significant bits
of the originator counter (64 bits) of successfully processed UTRNs.
The ESME checks that the UTRN counter is strictly numerically greater than the
lowest numerical value in the UTRN counter cache and is not equal to any value
in the UTRN counter cache. If the UTRN counter was not numerically greater
than the lowest numerical value in the UTRN counter cache, it would be
considered to be old. If the UTRN counter was equal to any value in the UTRN
counter cache, it would be considered to be a duplicate.
The UTRN counter cache updates under the following conditions:
• UTRN is successfully processed by the ESME; as such, a new entry is added
• Reset upon Update of Security Credentials command
UTRN - Manual Entry
Manual entry of a UTRN can only be done via the Prepayment menu by pressing
Button A until the
Enter Top-up Code
item is shown.
Press and hold Button A to enter the UTRN Top-up screen, where the following
can be used to enter the top-up code:
Enter UTRN Menu Options
Button Action
A Button Press
Increases the value of the digit selected by the
cursor by one
A Button Hold Exits the Enter UTRN display