ACR3901T-W1 – Reference Manual
Version 1.02
www.acs.com.hk
Page 60 of 100
7.1.14.
Customer Master Key Reset Request
This command requests the reader to generate a random number for the Customer Master Key Reset
authentication.
Command Format
Offset
Field
Size
Value
Description
0
abData1
CommandCode
1
0Fh
Command Code of Customer
Master Key Reset Request
1
Len (CommandLength)
1
00h
Number of extra bytes of data
2
Data
0
-
-
Response Format
Offset
Field
Size
Value
Description
0
abData2
ResponseCode
1
8Fh
Response Code of Rewrite
Master Key
1
Len (CommandLength)
1
10h
Number of extra bytes of data
2
Data
16
-
16 bytes of random number
(KeyRSTRnd[0:15]) generated
by the reader
Example:
1. Generate random number.
Customer Master Key Reset Request = 0F
00
Customer Master Key Reset Command Response = 8F 10
11 11 11 11 11 11 11 11 11 11 11
11 11 11 11 11
2. Encrypt the random number and new customer master key using the original customer
master key by AES128 CBC. This is done by the application’s encryption engine and result
will be stored for later use.
Random number:
11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11
Encrypted random number:
F1 9F D2 D2 BA 1C 22 E1 6D C1 FE 1B 4B 43 D5 30
New Customer Master Key:
11 22 33 44 55 66 77 88 11 22 33 44 55 66 77 88
Encrypted new Customer master key:
27 E7 DA BE A6 1E 4B CD 29 F6 9B 36 25 05 8E 41
3. Rewrite the Master Key (see
Rewrite Master Key Command Request = 07 20
F1 9F D2 D2 BA 1C 22 E1 6D C1 FE 1B 4B
43 D5 30
27 E7 DA BE A6 1E 4B CD 29 F6 9B 36 25 05 8E 41
Rewrite Master Key Command Response = 87 01
00
