AT88SC0808CRF 데이터 시트보기 (PDF) - Atmel Corporation
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AT88SC0808CRF Datasheet PDF : 9 Pages
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Communication
Security Modes
Security Methodology
Communication between the PICC and reader operates in three basic modes. Standard
mode is the default mode for the device after power-up and anticollision. Authentication
mode is activated by a successful authentication sequence. Encryption mode is
activated by a successful encryption activation, following a successful authentication.
Table 2. Configuration Security Modes
Mode
Standard
Authentication
Encryption
Configuration
Data(1)
clear
clear
clear
User Data
clear
clear
encrypted
Passwords
clear
encrypted
encrypted
Data Integrity
Check
MDC(2)
MAC(3)
MAC(3)
Notes: 1. Configuration data includes the entire configuration zone except the passwords.
2. Modification Detection Code
3. Message Authentication Code
Figure 3. Security Methodology
Device (card)
Card Number
VERIFY A
Compute Challenge B
Challenge B
Host (reader)
COMPUTE Challenge A
Challenge A
VERIFY B
Check Password RPW
DATA
Checksum (CS)
Check Password WPW
VERIFY CS
Write DATA
Read Password (RPW)
VERIFY CS
Write Password (WPW)
DATA
CS
Memory Access
Depending on the device configuration, the host will carry out the authentication protocol
and/or present different passwords for each operation: read or write. A bidirectional
secure checksum may be used to certify data authenticity. Each user zone may be
configured for free access for read and write or for password restricted access. To
insure security between the different user zones (multiapplication card), each zone can
use a different set of passwords. A specific attempts counter for each password and for
the authentication provides protection against systematic attacks.
Security Operations
Antitearing
In the event of a power loss during a write cycle, the integrity of the device’s stored data
may be recovered. This function is optional: the host may choose to activate the
antitearing function depending on application requirements. When antitearing is active,
write commands take longer to execute since more write cycles are required to
complete them. Data writes are limited to 8-byte pages when antitearing is active.
6 AT88SC0808CRF
5027AS–CRRF–05/03
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