Verify a MAC on a Binary Message

Command:

Verify a MAC on a binary message.

Note:

If the Host is unable to support binary data transfers, the command can be used in standard 7-bit asynchronous mode, whereupon the message to be MACed is transferred in expanded hexadecimal notation.

 

Field

Length & Type

Details

COMMAND MESSAGE

Message header

m A

(Subsequently returned to the Host unchanged).

Command code

2 A

Value MW.

Mode number

1 N

The MAC calculation mode number: 0 to 3.

0:  The only block.

1:  The first block.

2:  A middle block.

3:  The last block

Terminal authentication key

16H or 1A+32H or 1A+48H

TAK encrypted under LMK pair 16-17.

Initialization vector (IV)

16 H

Modes 2,3. IV returned from either mode 1 or 2 encrypted under variant 1 of LMK pair 16-17.

MAC

8 H

Modes 0,3. The MAC received with the unsolicited message.

EITHER

For Binary Communications Modes:

  

  

Message length

3 H

X’001 to X’320 indicating the length of the next field.

Message text

n B

1 to 800 bytes of message.

OR

For Standard Async Communications Mode:

  

  

Message length

3 H

X’002 to X’320 indicating the number of characters in the next field.

Message text

n H

2 to 800 hexadecimal characters representing 1 to 400 bytes of message.

End message delimiter

1 C

Optional. Must be present if a message trailer is present. Value X’19.

Message trailer

n A

Optional. Maximum length 32 characters.

 

 

 


 

Field

Length & Type

Details

RESPONSE MESSAGE

Message header

m A

Returned to the Host unchanged.

Response code

2 A

Value MX.

Error code

2 N

00 : No errors.

01 : MAC verification failure.

10 : TAK parity error.

12 : No keys loaded in user storage.

13 : LMK error; report to supervisor.

15 : Error in input data.

21 : Invalid user storage index.

27 : TAK not single length.

80 : Message length error (including odd number of characters when using standard async mode).  

90 : Communications link parity error.

91 : Communications link LRC error.

92 : Transparent async data length error.

IV

16 H

Present only in modes 1 and 2. The IV encrypted under variant 1 of LMK pair 16-17.

End message delimiter

1 C

Present only if present in the command message. Value X’19.

Message trailer

n A

Present only if present in the command message. Maximum length 32 characters.