CLRC632 Datasheet, PDF (137/163 Pages) NXP Semiconductors – Multiple Protocol Contactless Reader IC

Philips Semiconductors
Product Specification Rev. 3.0; May 2003
Multiple Protocol Contactless Reader IC
CL RC632
19 MIFARE^ CLASSIC AUTHENTICATION AND CRYPTO1
19.1 General
The security algorithm implemented in MIFARE^ Classic products is called Crypto1. It is based on a
proprietary stream cipher with a key length of 48 bits. To access data of a MIFARE^ Classic card, the
knowledge of the according key is necessary. For successful card authentication and subsequent access to
the card’s data stored in the EEPROM, the correct key has to be available in the CL RC632. After a card is
selected as defined in ISO14443A the user may continue with the MIFARE^ Classic protocol. In this case it
is mandatory to perform a card authentication. The Crypto1 authentication is a 3-pass authentication. This
procedure is done automatically with the execution of Authent1- (see 18.9.3) and the Authent2-Commands
(see 18.9.4). During the card authentication procedure, the security algorithm is initialised. The
communication with a MIFARE^ Classic card following a successful authentication is encrypted.
19.2 Crypto1 Key Handling
During the authentication command the CL RC632 reads the key from the internal key buffer. The key is
always taken from the key buffer. Therefore, the commands for Crypto1 authentication do not require
addressing of a key. The user has to ensure, that the correct key is prepared in the key buffer before the
card authentication is triggered.
The key buffer can be loaded
• from the E²PROM with the LoadKeyE2-Command (see 18.9.1)
• directly from the µ-Processor via the FIFO-Buffer with the LoadKey-Command (see 18.9.2)
This is shown in the following figure:
WriteE2
E²PROM:
Keys
From the
µController
.
FIFO
Serial Data Stream In
(Plain)
LoadKey
Key Buffer
LoadKeyE2
During
Authent1
Crypto1 Module
Serial Data Stream Out
(Encrypted)
Figure 19-1: Key Handling: Block Diagram
137
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