Advanced Card Systems Ltd. ACR3901T-W1, Reference Manual

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ACR3901T-W1 – Reference Manual
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Version 1.02
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Page 33 of 100
6.1.6.3. SPH_to_RDR_AuthRsp
This command is the second phase of the authentication process. After the device has initiated the
SPH_to_RDR_ReqAuth command to the ACR3901T-W1, the reader will then provide an
RDR_to_SPH_AuthRsp1 message if there’s no error.
The RDR_to_SPH_AuthRsp1 will contain a sequence of 16-byte random numbers encrypted using
the Customer Master Key. The paired key-generating device should decrypt it using the correct
Customer Master Key and pads it to the end of the 16-byte of random numbers. The overall 32-byte
random numbers will be decrypted using the Customer Master Key and return it to the ACR3901T-W1
using this command in order to have a successful authentication.
For more information on the authentication process, please refer to Authentication .
Offset Field Size Value Description Encrypted
0 bMessageType 1 71h - No
1
LEN1 LEN2
(wLength)
2 2100h
Number of extra bytes starting
from the next field for this
message, and is expressed in
two bytes long, and LEN1 is
LSB while LEN2 is MSB
No
3 abAuthData 32 -
abAuthData[0:15] – 16 bytes
of random number generated
by the data processing server.
abAuthData[16:31] – 16 bytes
of decrypted random number
received from ACR3901T-W1.
All the 32 bytes of data will be
decrypted with the Customer
Master Key using AES128
CBC cipher mode
Yes
35 wChecksum 1 -
CSUM means the XOR values
of all bytes in the command
No
The response to this message is RDR_to_SPH_AuthRsp2 if the command message received is error
free and the random number generated returned by the ACR3901T-W1 is correct.