AT88SC3216CRF-MS1 查看數據表（PDF） - Atmel Corporation
零件编号
产品描述 (功能)
生产厂家
AT88SC3216CRF-MS1 Datasheet PDF : 9 Pages
| |||
7. Security Operations
7.1 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.
Data is written first to a buffer zone in EEPROM instead of to the intended destination address,
but with the same access conditions. The data is then written to the required location. If this sec-
ond write cycle is interrupted due to a power loss, the device will automatically recover the data
from the buffer zone at the next power-up.
7.2 Password Verification
Passwords may be used to protect user zone read and/or write access. When a password is
presented using the Check Password command, it is memorized and active until power is
removed unless a new password is presented or a valid DESELECT or IDLE command is
received. Only one password is active at a time, but write passwords also give read access.
7.3 Authentication Protocol
The access to a user zone may be protected by an authentication protocol in addition to pass-
word dependent rights. Passwords are encrypted in authorization mode.
The authentication success is memorized and active as long as the chip is powered, unless a
new authentication is initialized or a valid DESELECT or IDLE command is received. If the new
authentication request is not validated, the card loses its previous authentication and it must be
presented again. Only the last request is memorized.
7.4 Encryption
The data exchanged between the card and the reader during Read, Write, and Check Password
commands may be encrypted to ensure data confidentiality.
The issuer may choose to protect the access to a user zone with an encryption key by settings
made in the configuration memory. In that case, activation of the encryption mode is required in
order to read/write data in the zone.
The encryption activation success is memorized and active as long as the chip is powered,
unless a new initialization is initiated or a valid DESELECT or IDLE command is received. If the
new encryption activation request is not validated, the card will no longer encrypt data during
read operations nor will it decrypt data received during write or Check Password operations.
7.5 Checksum
The PICC implements a data validity check function in the form of a checksum. The checksum
may function in standard or cryptographic mode. In the standard mode, the checksum is optional
and may be used for transmission error detection. The cryptographic mode is more powerful
since it provides data origin authentication capability in the form of a Message Authentication
Code (MAC). To write data to the device, the host is required to compute a valid MAC and pro-
vide it to the device. If after an ingoing command the device computes a MAC different from the
6 AT88SC3216CRF
5005DS–CRRF–04/09
Share Link: 