Rules Of Request Mac; Mac Packet Z67: Return Mac - VeriFone MX800 series Programmer's Manual

IPP MS DUKPT C
AND OMMUNICATIONS
MAC-Specific Packets
MAC Packet Z67:
Return MAC
338
M X 800 S P
ERIES ROGRAMMERS
P
ACKETS
6
If the working key is loaded in 1DES key-only format, either ANSI (standard)
or MAC is used (depending on the status of the flag in the packet Z66).
7
If the working key is loaded in the GISKE format, the IPP uses the MAC
algorithm specified in the Key Usage Attributes of the GISKE key block.
8
When the key length and the MAC algorithm do not match, an error code (key
attribute/usage error) returns. For example, a single-length key is used with a
3DES MAC algorithm.
9
MAC algorithms used: ISO 9797-1 MAC Algorithm 1–56 bits, MAC Algorithm
1–112 bits, MAC Algorithm 2–112 bits, MAC Algorithm 3–112 bits, MAC
Algorithm 4–112 bits, MAC Algorithm 5–56 bits, MAC Algorithm 5–112 bits.
10
The GISKE working key can only be a single- or double-length key. Master
key used to encrypt the working key can be a single-, double-, or triple-length
key (the GISKE length encryption rule still applies). If a triple-length GISKE
working key is used in Z66, a working key error is returned.

Rules of Request MAC

The following rules are imposed to the size of the "Message for MAC" field:
Table 88 Rules for Request MAC
Packet
Size of X
Type
Key- ASCII: X = 0, 1, 2 – 27,
only 28
format
Binary: X = 0, 2, 4 – 26,
28
GISKE ASCII: X = 0, 1, 2 – 14,
Key 15
Block
Format
mode
Binary: X =0, 2, 4 – 12,
14
This multi-purpose packet:
•
Sends a signal to the master device that the IPP is ready for the next Z66
packet.
•
Sends an error code to the master device if there any error is detected during
the MAC session.
G
UIDE
Maximum Size Apply to
of Message Message
(bytes) Sequence
224
00–99
224
120 00 – 99
112
Comments
Due to size
of GISKE
key block,
the size of
message is
reduce to
120 bytes.