User's Manual

PIN Pad 791 Programmer’s Manual (PCI POS-A) UDN PM0103-U Rev. 06
Section 9 – Online transaction messages with Master / Session keys 2015-04-20
Page216
Uniform Industrial Corp. Proprietary and Confidential Total 342 pages
Message Z2 Display String with Authentication Code
Format: <STX>Z2<FS>[KeyID][MAC][Mode][string]<SUB><ETX>[LRC]
(Request frame)
<STX>Z2[status]<ETX>[LRC]
(Response frame)
Message length: Variable.
Usage: This command allows acquirer to show free message on screen as prompt for clear
text entry (Z42, Z50) and PIN entry (Z60). PP791 will verify MAC value by the following
rule:
* Collect [Mode] character, [string] (exclude white space, punctuation marks and
digits), and <SUB> character (if exist), as byte array, padding with ASCII ‘0’ (0x30) to
the multiple of 8.
* Use the key specified by [KeyID] and ISO-9797-1 Algorithm 3 to generate message
authentication code for above data.
* Compare the leftmost 4 bytes of MAC value and the one written in the Z2 command.
If MAC value matches, PP791 will display the [string] written in Z2 command.
Note: 1. If Z2 (string with MAC) is used in combination with Z2 (fixed prompt), their mode
character (GS / RS) must be the same; Otherwise PIN pad will reject secondary Z2.
2. PIN pad will temporarily turn off timer display for the first Z2 message it received.
After Z42, Z50, Z60 are performed, [CAN] key is pressed, or any other message
received and processed, PIN pad will turn on the timer display.
Message element :
Z2 with MAC, request frame
Field Length Value and description
<STX> 1 <02>
Z2 2 Message ID
<FS> 1 <1C>, field separator.
[KeyID] 1 ‘B’ ~ ‘E’, key to verify MAC value. The
specified key must have usage ‘M3’ and
mode ‘V’.
[MAC] 8 Message authentication code of following
message (including <SUB> if exist).
[Mode] 1 <GS> (0x1D) for Non-PIN entry.
<RS> (0x1E) for PIN entry.
[string] 1 .. 62 ASCII string to be displayed
<SUB> 1 <1A> (optional)
When <SUB> exists, PIN pad will clear