Validate the S₁ MAC (Currency Exchange)

Command:

Validate the S₁ 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.

Field

Length & Type

Details

COMMAND MESSAGE

Message Header

m A

Will be returned to the Host unchanged

Command Code

2 A

Value “U6”

*KMX

32 H or 1A+32H

Double length KMX encrypted under LMK pair 20-21 variant 2

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

TI

1 B

Transaction Indicator
‘08’ for currency exchange transactions

DTHR_LDA

5 B

Transaction date and time

CURR_SOURCE

3 B

The Currency Code for the source slot

ID_LACQ

4 B

Load Acquirer ID

ID_LDA

6 B

The Identifier for the Load Device

M_LDA

4 B

The Transaction amount

NT_LASTLOAD

2 B

Transaction number of last load

NT_LASTCANCEL

2 B

Transaction number of last cancel

CSTAT_CEP

2 B

Card Status

TLfail_CEP

1 B

Tag and Length of failed update

DEXP_CEP

3 B

Expiry date of the card, YYMMDD

CURR_TARGET

3 B

The Currency Code

BAL_TARGET

4 B

Balance of target slot

BALmax_TARGET

4 B

Maximum balance of the target slot

BAL_SOURCE

4 B

Balance of source slot

S₁

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 “U7”

Error Code

2 N

00 – No error. S1 validated successfully

01 – S1 validation failed.

10 – KDX 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