ACS ACR1255U-J1, Reference Manual

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ACR1255U-J1 – Reference Manual
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5.7. Mutual Authentication and Encryption Protocol
In Bluetooth mode, the communication protocol in Section 5.6 will be encrypted and transmitted after
a successful mutual authentication.
5.7.1. Bluetooth Authentication Program Flow
As illustrated in Section 5.3 , mutual authentication is being used to avoid man-in-the-middle attack.
The summary of the commands used in mutual authentication is in the following table:
Sequence Command Mode Supported Sender Description
1 6Bh Connected Paired device SPH_to_RDR_ReqAuth
2 83h Connected Reader RDR_to_SPH_AuthRsp1
3 6Bh Connected Paired device SPH_to_RDR_AuthRsp
4 83h Connected Reader RDR_to_SPH_AuthRsp2
Table 8 : Summary of Mutual Authentication Commands
The 16-byte Session Key, SK[0:15,] is generated in both ACR1255U-J1 and the data processing
server. It is obtained by padding the first 8 bytes of RND_B at the end of the first 8 bytes of RND_A,
i.e.
SK[0:15] = RND_A[0:7] + RND_B[0:7]
5.7.2. SPH_to_RDR_ReqAuth
This command will request ACR1255U-J1 to perform authentication with the paired key-generating
device.
For more information on the authentication process, please refer to Section 5.3 .
Offset Field Size Value Description Encrypted
0 bMessageType 1 6Bh
No
1 LEN1 LEN2 (wLength) 2 0005h
The Number of extra
bytes in Data field, and is
expressed in two bytes
long, and LEN1 is MSB
while LEN2 is LSB;
3
Slot Number
1 00h
4
Sequence
1 00h
5
Parameter
1 00h Slot Status
6 wChecksum 1 CBh
CSUM means the XOR
values of all bytes in the
command
7 Data 5 E0 00 00 45 00h No
The response to this message is RDR_to_SPH_AuthRsp1 if the received command message is error-
free. Otherwise, the response message will be RDR_to_SPH_ACK to provide the error information.