at88sc0104ca ATMEL Corporation, at88sc0104ca Datasheet - Page 12

• Manufacturer Part Number: at88sc0104ca
• Description: Cryptomemory
• Manufacturer: ATMEL Corporation

11.1
12. Communication Security Modes
Table 12-1.
Note:
13. Security Options
13.1
12
Mode
Standard
Authentication
Encryption
Security Fuses
1. Configuration data include viewable areas of the Configuration Zone except the passwords:
Anti-Tearing
AT88SC0104CA
MDC: Modification Detection Code.
MAC: Message Authentication Code.
Communication Security Modes
There are three fuses on the device that must be blown during the device personalization pro-
cess. Each fuse locks certain portions of the configuration zone as OTP (One-Time
Programmable) memory. Fuses are designed for the module manufacturer, card manufacturer
and card issuer and should be blown in sequence, although all programming of the device and
blowing of the fuses may be performed at one final step.
Communications between the device and host operate in three basic modes. Standard mode is
the default mode for the device after power-up. Authentication mode is activated by a successful
authentication sequence. Encryption mode is activated by a successful encryption activation fol-
lowing a successful authentication.
In the event of a power loss during a write cycle, the integrity of the device’s stored data is recov-
erable. This function is optional: the host may choose to activate the anti-tearing function,
depending on application requirements. When anti-tearing is active, write commands take longer
to execute, since more write cycles are required to complete them, and data is limited to a maxi-
mum of eight bytes for each write request.
Data is written first into a buffer zone in EEPROM instead of the intended destination address,
but with the same access conditions. The data is then written in 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 system buffer zone at the next power-up. Non-volatile buffering of the data is done
automatically by the device.
During power-up in applications using Anti-Tearing, the host is required to perform ACK polling
in the event that the device needs to carry out the data recovery process.
Configuration Data
Clear
Clear
Clear
(1)
User Data
Encrypted
Clear
Clear
Passwords
Encrypted
Encrypted
Clear
Data Integrity Check
5200BS–CRYPT–2/09
MDC
MAC
MAC
(1)
(1)
(1)