mfrc531 NXP Semiconductors, mfrc531 Datasheet - Page 40

• Manufacturer Part Number: mfrc531
• Description: Iso/iec 14443 Reader Ic
• Manufacturer: NXP Semiconductors

NXP Semiconductors
MFRC531_34
Product data sheet
PUBLIC
9.14.1 Crypto1 key handling
9.14 MIFARE authentication and Crypto1
The security algorithm used in the MIFARE products is called Crypto1. It is based on a
proprietary stream cipher with a 48-bit key length. To access data on MIFARE cards,
knowledge of the key format is needed. The correct key must be available in the
MFRC531 to enable successful card authentication and access to the card’s data stored
in the EEPROM.
After a card is selected as defined in ISO/IEC 14443 A standard, the user can continue
with the MIFARE protocol. It is mandatory that card authentication is performed.
Crypto1 authentication is a 3-pass authentication which is automatically performed when
the Authent1 and Authent2 commands are executed (see
Section 11.6.4 on page
During the card authentication procedure, the security algorithm is initialized. After a
successful authentication, communication with the MIFARE card is encrypted.
On execution of the authentication command, the MFRC531 reads the key from the key
buffer. The key is always read from the key buffer and ensures Crypto1 authentication
commands do not require addressing of a key. The user must ensure the correct key is
prepared in the key buffer before triggering card authentication.
The key buffer can be loaded from:
Fig 14. Crypto1 key handling block diagram
•
•
the EEPROM using the LoadKeyE2 command (see
the microprocessor’s FIFO buffer using the LoadKey command (see
on page
from the microcontroller
88). This is shown in
Rev. 3.4 — 26 January 2010
89).
FIFO BUFFER
056634
Figure
serial data stream in
(plain)
14.
LoadKey
WriteE2
KEY BUFFER
CRYPTO1
EEPROM
MODULE
Section 11.6.1 on page
KEYS
Section 11.6.3 on page 89
during
Authent1
ISO/IEC 14443 reader IC
serial data stream out
(encrypted)
LoadKeyE2
MFRC531
© NXP B.V. 2010. All rights reserved.
Section 11.6.2
001aak624
88)
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