PCF7936AS/3851/C,1-CT NXP Semiconductors, PCF7936AS/3851/C,1-CT Datasheet - Page 18

• Manufacturer Part Number: PCF7936AS/3851/C,1-CT
• Description: pcf7936as series 32-bit 125 khz read / write security...
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Security Transponder (HITAG2)
START_AUTH (Cipher Mode)
If configured for Cipher mode, START_AUTH triggers the
mutual device authentication sequence. If completed
successfully, the device enters AUTHORIZED state and
subsequently supports ciphered read and write access of
the Transponder Memory, TM. Device authentication
employs the Identifier, a Random Number, a ciphered
Signature and a ciphered device Response, see Figure 13.
After acceptance of the 5 bit command sequence, the initial
device Response consist of the 32 bit Identifier (IDE) that is
stored in the Transponder Memory. Subsequently, the
interrogating system (e.g. basestation) has to identify itself
towards the device, by issuing a 32 bit Random Number
and a matching 32 bit ciphered Signature. The device
verifies the authenticity of the ciphered Signature received,
by means of the Calculation Unit, involving the Secret Key
(SK). If successful, the final device Response consists of
the ciphered content of page 3 that contains the
Transponder and Memory configuration (TMCF) and device
Password Transponder (PSW
2010 May 04
Figure 14. START_AUTH timing
SEND to
Transponder
RECEIVED from
Transponder
START_AUTH
CM[4:0]
1 1 0 0 0
T
). The MSB is send first.
SEND to
Transponder
RECEIVED from
Transponder
1 1 1 1 1
EQ
t
WAIT,Tr
bit 31 ..............bit 0
IDE
18
In case the authentication process fails, an error condition
occurs that causes the device to terminate the command
and to enter WAIT state. The device will send no further
Response in this case.
Subsequent commands may be issued after termination of
the final t
For proper command execution, the interrogating system
has to identify itself towards the device within the specified
IDLE time, otherwise the device may generate a power-on
reset condition, upon which the circuitry would be reset and
the transponder initialized, causing the device to enter the
WAIT state.
The Security Algorithm details, involved in the process of
mutual device authentication, are specified in a separate
Application Note. Please contact your NXP representative
for more information.
1 1 1 1 1
EQ
t
WAIT,Tr
bit 31 ..............bit 0
Random Number
WAIT,Bs
[Page 3 Block 0]
t
bit 31 ..............bit 0
WAIT,Bs
.
t
IDLE
CIPHER
bit 31 ..............bit 0
[Signature]
Product Specification
CIPHER
t
WAIT,Bs
PCF7936AS
CONFIDENTIAL