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
59
Chapter 6 • Advanced Features
There are a number of departures from the currently specified IEC 62055-41 that
are required for the Class 5 Token, which are mainly the ability to have an
unencrypted token and secondly the ability to have a built-in MAC for token
authentication.
Consumer UTRN Token — 20-Digit Decimal
Under normal circumstances, the consumer will provide the ESME ID and
purchase credit for their meter. A UTRN token is generated, and the request is sent
to the ESME over the WAN communications to the communications hub and then
on to the ESME over the HAN.
Should the WAN communications channel be off-line, the consumer must
manually enter the UTRN token via the ESME UI or, if available, the PPMID UI.
Check Digit — 20th Digit
The Check Digit is used to verify the correct entry of the preceding 19-digit PPTD
in instances where it is entered manually. This verifies accuracy of the entry,
reducing human error.
The Check Digit adopts the Verhoeff alogrithm. Erroneous entries detected by the
Verhoeff algorithm aren't penalized as invalid entries – the lockout counter isn't
incremented (see UTRN Entry Lockout on page 62).
UTRN Token – MAC
The message authentication code (MAC) is GMAC based on a 128-bit symmetric
key (prepayment key) that is derived each time a UTRN token is generated. The
following diagram gives an overview of the data elements involved in that
generation.
Token K Classes
Constant Value – Decimal Value – Hex Purpose
K_Class
0_1_ 2_3_MIN
00 000 000 000 000 000 000 0x0 0000 0000 0000 0000
MIN Class 0, 1, 2, 3
token value
K_Class
0_1_ 2_3_MAX 73 786 976 294 838 206 463 0x3 FFFF FFFF FFFF FFFF
MAX Class 0, 1, 2, 3
token value
K_Class _4_MIN 73 786 976 294 838 206 470 0x4 0000 0000 0000 0006 MIN Class 4 token value
K_Class_4_MAX 73 941 569 907 863 060 479 0x4 0225 3A12 6CE3 FFFF MAX Class 4 token value
K_Class
5_OFFSET
(19 digit)
7 394 156 990 786 306 048 0x669D 529B 714A 0000
Constant to add on to
Class 5 token
K_Class_5_MIN 73 941 569 907 863 060 480 0x4 0225 3A12 6CE4 0000 MIN Class 5 token value
K_Class_5_MAX 96 999 999 999 999 999 999 0x5 4225 3A12 6CE3 FFFF MAX Class 5 token value
K_Class_6_MIN 97 000 000 000 000 000 000 0x5 4225 3A12 6CE4 0000 MIN Class 6 token value
K_Class_6_MAX 99 999 999 999 999 999 999
0x5 6BC7 5E2D 630F
FFFF
MAX Class 6 token value