F-64/F-128-Message Authentication Code

Description

This field contains a Message Authentication Code (MAC) - a mechanism to validate the content of the message between the sender and the receiver. The field contains 8 bytes of raw binary data.

The MAC must be provided in Field 64 only when the message utilizes fields in the first bitmap only (fields 1-64), or in Field 128 only when the message utilizes one or more fields in the second bitmap (65-128).

To ensure messages are MACed consistently, they must be prepared consistently. As such, each message will be MACed without the MAC field set, and without the corresponding bit set in the bitmap.

Attributes

b 8