Data Sheet

Chips and readers- USER’S GUIDE
UG 22
Version 1.0
TERMINOLOGY AND NOTATION
Adding p after the key name means that the key is permuted.
Adding chk means that the 8
th
byte replaced by the Checksum byte value.
A C before the key name means that the key has been encrypted.
Abbreviation Meaning
K
ex
Exchange Key.
K
ex
p Permuted Exchange Key.
K
ex
p_chk Kep with the 8
th
byte replaced by the Checksum byte value.
Rnd Random number.
K
x
Master key. (K
x
equals to K
d
or K
c
)
K
x
p Permuted master key. (K
x
p equals to K
d
p or K
c
p)
CKxp Encrypted permuted master key. (CK
x
p equals to CK
d
p or CK
c
p)
SK Session key.
CHK 4-byte checksum.
KEY LOADING STEP BY STEP
We assume that the default keys are used.
STEP DESCRIPTION Example
!
Send the
Ask_Random
command
Send
80h 84h 00h 00h 08h. The coupler answer a
random number.For this example, we assume that
Rnd = 00 00 00 00 00 00 00 00.
The session key is define by the following formula :
SK = Kexp_chk
⊕
Rnd (
⊕
: bit to bit x-or
operation)
K
ex
p_chk means that we have to permute K
ex
then
to replace the 8
th
byte by the checksum byte
!
Permute the exchange key to get K
ex
pK
ex
p = 6E FD 46 EF CB B3 C8 OB
!
replace the 8
th
byte by the checksum byte
to get K
ex
p_chk
K
ex
p_chk = 6E FD 46 EF CB B3 C8 75
!
Calculate the session key SK = 6E FD 46 EF CB B3 C8 75
This calculation include the exchange key through
the session key (SK). This insure the protection of
the new key value.
CK
x
p = SK
⊕
K
x
p (
⊕
: bit to bit x-or operation) CK
d
p = 91 F2 75 BA CB 43 04 20
!
Permute the new key value K
x
to get K
x
p
!
Make a bit to bit X-OR operation with the
session key SK
!
Calculate the CheckSum
!
Send the command to the coupler.
Load_Key_File
(CKxp + CheckSum)
CheckSum
= 73 27 FF 01
Send
80 D8 00 01 0C & 91 F2 75 BA CB 43 04 20 &
73 27 FF 01
Step 1 : Get a random number from the coupler
Step 2 : Calculate the Session Key
Step 3 : Calculate the Encrypted master key
Step 4 : Send the
Load_Key_File
command