Binary MAC commands, used by ACI's Base24 Release 5, allow the HSM to compute a MAC on binary data. See also the MQ command which provides a binary MAC facility.
Some Host computers cannot handle binary data in a normal async environment. When the HSM is set up for normal async the binary data is assumed to be supplied in expanded hexadecimal notation (i.e., each binary byte is converted to two hexadecimal characters). This has the effect of doubling the amount of data sent to the HSM.
Unlike the standard MAC commands, MA, MC and ME, the Binary MAC commands make no assumptions about the format or representation of the supplied MAC data; they compute a MAC on the exact binary values supplied regardless of character format. Note, however, that the keys and other values are assumed to be in hexadecimal character format. Only the MAC data field accepts binary data.