Data Sheet

Chips and readers- USER’S GUIDE
UG 12
Version 1.0
Authentication
Authentication algorithm performs a mutual authentication.
The principle is as follows : Data are exchanged then both device perform secret
calculations on them to obtain 2 results on 4 bytes. Authentication is done if they get the
same results. The chip first checks coupler’s response then reader verifies chip’s results.
1. Coupler and chip
exchange data
Data (64bits) Random (32 bits)
Diversified
secret key
2. Both coupler and
chip calculate 2
results on 4 bytes
Diversified
secret key
(64 bits)
3. The chip verifies the
coupler's result 1, then
send Result 2 if OK
4. The coupler checks
chip's answer (Result 2)
R1 R2 R1 R2
Coupler
Signature
Each time you want to send data to the chip, a 32 bits signature is automatically calculated
and added. Signature calculation takes into account the diversified key value (result of
operation between key value and chip serial number) and the data. Chip will check the
signature to allow data writing. This ensures very good security on the chip content.
Coup ler
Host
Key Value Chip serial number
Diversified key value
Signature
Data
Data &
signature
Chi p
Signature calculation principle
Signature
when writing
increases memory
content security
Authentication
protects the memory
from reading and
writing
Note :
Diversified key is written in
the chip during personalization
phase, and calculated after
each card selection by the
coupler (div. key depends on
the chip serial number)