Command:

Validate the S₃ MAC for currency exchange transactions.

Notes:

Use of this command requires the optional ESP licence. Error code 67 will be returned if the command is not licensed.

After a CEP card completes processing, it generates an S₃ MAC to prove to the issuer that the currency exchange transaction was completed successfully.  The load processor uses this function to verify the S₃ MAC.

Field

Length & Type

Details

COMMAND MESSAGE

Message Header

m A

Will be returned to the Host unchanged

Command Code

2 A

Value “V4”

*KM3X

32 H or 1A+32H

Double length KM3X encrypted under LMK pair 20-21 variant 6

ID_CEP

6 B

The CEP Card Identifier. Used to create the *KDX

NT_CEP

2 B

The transaction number assigned by the Load Acquirer

CC_TRX

2 B

Transaction Completion Code

TI

1 B

Transaction Indicator
‘08’ for currency exchanges

DTHR_LDA

5 B

Transaction date and time

CURR_LDA,SOURCE

3 B

The Currency Code

ID_LACQ

4 B

Load Acquirer ID

ID_LDA

6 B

The Identifier for the Load Device

M_LDA

4 B

The Transaction amount

CURR_LDA,TARGET

3 B

The Currency Code

BAL_CEP,TARGET

4 B

Balance of slot prior to completion

BAL_CEP,SOURCE

4 B

Balance of slot prior to completion

S₃

8 B

Signature for verification

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

Will be returned to the Host unchanged

Response Code

2 A

Value “V5”

Error Code

2 N

00 – No error. S₃ validated successfully

01 – S₃ validation failed.

10 – KML 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

70 – Invalid transaction indicator

End Message Delimiter

1 C

Will only be present if present in the command message. Value X'19

Message Trailer

n A

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