CLRC632 View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
'CLRC632' PDF : 127 Pages View PDF
NXP Semiconductors
CLRC632
Standard multi-protocol reader solution
9.2.3 Crypto1 keys (write only)
MIFARE security requires specific cryptographic keys to encrypt data stream
communication on the contactless interface. These keys are called Crypto1 keys.
9.2.3.1 Key format
Keys stored in the EEPROM are written in a specific format. Each key byte must be split
into lower four bits k0 to k3 (lower nibble) and the higher four bits k4 to k7 (higher nibble).
Each nibble is stored twice in one byte and one of the two nibbles is bit-wise inverted. This
format is a precondition for successful execution of the LoadKeyE2 (see Section 11.7.1 on
page 97) and LoadKey commands (see Section 11.7.2 on page 97).
Using this format, 12 bytes of EEPROM memory are needed to store a 6-byte key. This is
shown in Figure 7.
Master key byte
0 (LSB)
1
Master key bits k7 k6 k5 k4 k7 k6 k5 k4 k3 k2 k1 k0 k3 k2 k1 k0 k7 k6 k5 k4 k7 k6 k5 k4 k3 k2 k1 k0 k3 k2 k1 k0
EEPROM byte
address
n
n+1
n+2
n+3
Example
5Ah
F0h
5Ah
E1h
Fig 7. Key storage format
5 (MSB)
k7 k6 k5 k4 k7 k6 k5 k4 k3 k2 k1 k0 k3 k2 k1 k0
n + 10
n + 11
5Ah
A5h
001aak640
Example: The value for the key must be written to the EEPROM.
• If the key was: A0h A1h A2h A3h A4h A5h then
• 5Ah F0h 5Ah E1h 5Ah D2h 5Ah C3h 5Ah B4h 5Ah A5h would be written.
Remark: It is possible to load data for other key formats into the EEPROM key storage
location. However, it is not possible to validate card authentication with data which will
cause the LoadKeyE2 command (see Section 11.7.1 on page 97) to fail.
9.2.3.2 Storage of keys in the EEPROM
The CLRC632 reserves 384 bytes of memory in the EEPROM for the Crypto1 keys. No
memory segmentation is used to mirror the 12-byte structure of key storage. Thus, every
byte of the dedicated memory area can be the start of a key.
Example: If the key loading cycle starts at the last byte address of an EEPROM block, (for
example, key byte 0 is stored at 12Fh), the next bytes are stored in the next EEPROM
block, for example, key byte 1 is stored at 130h, byte 2 at 131h up to byte 11 at 13Ah.
Based on the 384 bytes of memory and a single key needing 12 bytes, then up to 32
different keys can be stored in the EEPROM.
Remark: It is not possible to load a key exceeding the EEPROM byte location 1FFh.
CLRC632
Product data sheet
COMPANY PUBLIC
All information provided in this document is subject to legal disclaimers.
Rev. 3.7 — 27 February 2014
073937
© NXP Semiconductors N.V. 2014. All rights reserved.
18 of 127
Share Link: 
