HT-CM400 NXP Semiconductors, HT-CM400 Datasheet - Page 101

• Manufacturer Part Number: HT-CM400
• Description: Ht Cm400; Ht Rm440 Family; Ht Rm800 Family Interface Protocol Reader - Host
• Manufacturer: NXP Semiconductors

98-02-10
5.4.2 Changing Passwords and Keys
You do not have to change passwords and keys in order to operate a system with the
read/write device because access to the secret area of the transponder is possible with the
Transport Passwords and Transport Keys. Nevertheless, we strictly recommend to change
these data to be sure no other person (and nobody of Philips Semiconductors) than that
who got the authorization from you are able to access the secret area of the transponder.
If you change passwords and keys, you have to place the transponder directly on the
antenna or hold it directly to it (0-distance)! In order to avoid any errors do not move the
transponder during this write process and be sure that you are in a safe environment
without electrical noise.
5.4.2.1 Changing Password RWD and Keys
Please, note the order of the steps!
1.
2.
3.
Caution: You need to know the old value if you want to change the passwords or keys on the
read/write device!
5.4.2.2 Incorrect Procedures Changing Password RWD and Keys
The same scenario applies if you first change values on the transponder but leave the
corresponding values on the read/write device unchanged (transport key).
5.4.2.3 Changing Password TAG
To change Password TAG on HITAG 2 transponders in Password Mode or Crypto Mode use the
same procedure as described for changing Password RWD and keys. Be careful to change them
by pairs (on the read/write device and on the transponder):
1.
2.
Again, you need to know the old values before they can be changed on the read/write
device.
You change values on the read/write device and then try to access the transponder. This is not
possible because there is no identity between any of the keys on the transponder and the
read/write device.
Change Password TAG on the transponder. Password TAG and the Configuration Byte are
located on Page 3 of the transponder. In order not to change the value of the Configuration
Byte it is recommended to read Page 3 from the transponder. Byte 0 is left unchanged, and
Bytes 1..3 are set to the new Password TAG value. Then Byte 0 to Byte 3 are written to the
transponder.
Change Password TAG on the read/write device to the new value.
Select the transponder.
If the transponder is in Password Mode, you only have to overwrite Page 1 (Password
RWD).
If the transponder is in Crypto Mode, you have to overwrite Page 1 (KEY LOW) and
2 upper bytes of Page 3 (KEY HIGH).
It is recommended to execute a read-access test to check the changed values.
Change the corresponding data on the read/write device to the new values.
Page 101 (104)
Rev. 1.0
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