VeriFone MX800 Series - Rules of Request MAC; MAC Packet Z67: Return MAC

IPP MS AND DUKPT COMMUNICATIONS PACKETS
MAC-Specific Packets
338 M
X
800 SERIES PROGRAMMERS GUIDE
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:
MAC Packet Z67:
Return MAC
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.
Table 88 Rules for Request MAC
Packet
Type
Size of X
Maximum Size
of Message
(bytes)
Apply to
Message
Sequence
Comments
Key-
only
format
ASCII: X = 0, 1, 2 – 27,
28
224
00–99
Binary: X = 0, 2, 4 – 26,
28
224
GISKE
Key
Block
Format
mode
ASCII: X = 0, 1, 2 – 14,
15
120 00 – 99 Due to size
of GISKE
key block,
the size of
message is
reduce to
120 bytes.
Binary: X =0, 2, 4 – 12,
14
112