HT-CM400 NXP Semiconductors, HT-CM400 Datasheet - Page 102

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

Security Considerations
6 Security Considerations
Developing the read/write device special consideration was given to aspects of security. The
following items represent the fundamental framework of the security concept:
6.1 Data Reliability
6.1.1 Data Stream between Read/Write Device and Transponder
HITAG 1 transponders:
All the commands and data transferred from the read/write device to the transponder are secured
by Cyclic Redundancy Check (CRC).
Every data stream sent (commands, addresses, user data) from the read/write device to the
transponder is checked for data errors by the transponder by means of an integrated 8-bit CRC
generator.
The CRC is formed over commands and addresses or the plain data respectively and in the case of
Crypto Mode it is also encrypted.
The generator polynomial of the transponder CRC generator reads:
The CRC preassignment is:
HITAG 2 transponders:
Every command sent from the read/write device to the transponder is checked for data errors by
the transponder.
Standard commands transferred from the read/write device to the transponder are divided into
two Bit Streams. The second Bit Stream is generated by inverting the bits of the first Bit Stream.
This redundancy increases data security.
6.1.2 Checking User Data
Security of the data read from the transponder by the read/write device remains with the user for
reasons of flexibility.
Therefore, you can choose flexible check sums and store them in the transponder memory
together with the data. You can protect sensitive data better than less sensitive data, thus
permitting optimised operation times.
Detailed instructions how to use and calculate Cyclic Redundancy Check (CRC) are available at
Philips Semiconductors in the following Application Note:
HT1 (resp. HT2) Transponder Family, Reliability and Integrity of Data Transmission.
Htswp.doc/HS
u 8 + u 4 + u 3 + u 2 + 1 = 0x1D
cryptography
mutual authentication
password verification and
Cyclic Redundancy Check (CRC)
0xFF
Page 102 (104)
Rev. 1.0
98-02-10