Command 0X12 - Deactivate Authenticated Mode (Msr Only) - Magtek eDynamo Programmer's Manual

8 - Commands

8.3.8 Command 0x12 - Deactivate Authenticated Mode (MSR Only)

This command is used to exit Authenticated Mode initiated by Command 0x10 - Activate
Authenticated Mode. It can be used to exit the mode with or without incrementing the DUKPT
transaction counter (lower 21 bits of the Key Serial Number). The host software must send the first 7
bytes of Challenge 2 (from the response to Command 0x10 - Activate Authenticated Mode) and the
Increment flag (0x00 indicates no increment, 0x01 indicates increment the KSN) encrypted with a custom
variant of the current DUKPT Key (Key XOR 3C3C 3C3C 3C3C 3C3C 3C3C 3C3C 3C3C 3C3C).
If the device decrypts Challenge 2 successfully, it exits Authenticated Mode, and depending on the
Increment flag, may increment the KSN.
If the device cannot decrypt Challenge 2 successfully, it stays in Authenticated Mode until either the time
specified in Command 0x10 - Activate Authenticated Mode elapses or the cardholder or operator
swipes a card. This behavior is intended to discourage denial of service attacks. Exiting Authenticated
Mode by timeout or card swipe always increments the KSN; exiting Authenticated Mode using
Command 0x12 - Deactivate Authenticated Mode may increment the KSN.
Table 8-14 - Request Data for Command 0x12 - Deactivate Authenticated Mode (MSR Only)
Offset Field Name
Response to
0
Challenge 2
Response Data: None
Result codes:
0x00 = Success
0x02 = Bad Parameters - the Data field in the request is not the correct length
0x03 = Bad Data - the encrypted reply data could not be verified
0x07 = Sequence - not expecting this command
Example Request (Hex)
Cmd Num
12
Example Response (Hex)
Result Code
00
eDynamo| Secure Card Reader Authenticator | Programmer's Manual (COMMANDS)
Seven bytes of Challenge 2 plus one byte of Increment flag, encrypted by
the specified variant of the current DUKPT Key
Data Len
08
00
Page 76 of 245 (D998200115-17)
Description
Data
8579827521573495
Data Len Data