AT88SC0204CA-SH ATMEL [ATMEL Corporation], AT88SC0204CA-SH Datasheet - Page 11

• Manufacturer Part Number: AT88SC0204CA-SH
• Description: Atmel CryptoMemory
• Manufacturer: ATMEL [ATMEL Corporation]

8.1
9.
10.
10.1
10.2
Security Fuses
There are three fuses on the device that must be blown during the device personalization process. 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.
Communication Security Modes
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 following a successful authentication.
Table 9-1.
Note:
Security Options
Anti-tearing
In the event of a power loss during a write cycle, the integrity of the device’s stored data is recoverable. 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 maximum 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 second 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.
Write Lock
If a user zone is configured in the write lock mode, the lowest address byte of an 8-byte page constitutes a write access byte
for the bytes of that page.
Example:
Table 10-1. Write Lock Example
Mode
Standard
Authentication
Encryption
Address
$080
1.
Communication Security Modes
Configuration data include viewable areas of the configuration zone except the passwords:
The write lock byte at $080 controls the bytes from $081 to $087
11011001


$0
MDC: Modification Detection Code
MAC: Message Authentication Code
Configuration Data
xxxx xxxx
locked
$1
Clear
Clear
Clear
xxxx xxxx
locked
$2
(1)
User Data
xxxx xxxx
Encrypted
Clear
Clear
$3
Atmel AT88SC0204CA [Summary DATASHEET]
xxxx xxxx
$4
Passwords
Encrypted
Encrypted
Clear
xxxx xxxx
locked
$5
xxxx xxxx
5202FS−CRYPTO−12/11
Data Integrity Check
$6
MDC
MAC
MAC
xxxx xxxx
(1)
(1)
(1)
$7
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