ATSGA204A データシートの表示（PDF） - Microchip Technology

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ATSGA204A

Microchip CryptoAuthentication

Microchip Technology 

ATSHA204A

Device Organization

Word (HEX)

0x03

0x04

0x05

0x06

0x07

0x08

0x09

0x0A

0x0B

0x0C

0x0D

0x0E

0x0F

Address (HEX)

0x0C

0x10

0x14

0x18

0x1C

0x20

0x24

0x28

0x2C

0x30

0x34

0x38

0x3C

Default

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

0xFFFFFFFF

2.1.4

Device Locking

There are two separate lock bytes for the device:

• One to lock the configuration zone (that is controlled by LockConfig, byte 87).

• One to lock both the Data and OTP zones (that are controlled by LockValue, byte 86). This enables

the access polices for each Data zone slot based on the Slot configuration.

These locks are stored within separate bytes in the Configuration zone and can be modified only through

the Lock command. After a memory zone is locked, there is no way to unlock it. Locking of the Data/OTP

zone does not mean the slots can not be modified. The slots can be modified based on the access

policies defined by the Slot configuration.

The device should be personalized at the system manufacturer with the desired configuration information

and the Configuration zone should be locked. When this lock is complete, all necessary writes of public

and secret information into the EEPROM slots should be performed using encrypted writes if appropriate.

Upon completion of writes to the data and OTP zones, the Data and OTP zones the LockValue byte

should be written.

It is vital that the LockValue byte be set to lock prior to release of the system containing the device into

the field in order to protect the data stored in the Data and OTP zones. Failure to lock these zones may

permit modification of any secret keys and may lead to other security problems.

Any attempt to read or write the Data or OTP sections prior to locking the configuration section causes

the device to return an error.

Contact Microchip for optional secure personalization services.

2.1.4.1

Configuration Zone Locking

Certain bytes within the configuration zone cannot be modified, regardless of the state of LockConfig.

Access to the remainder of the bytes within the zone is controlled using the LockConfig byte in the

configuration zone, as shown in the table below. Throughout this document, if LockConfig is 0x55, then

the configuration zone is said to be unlocked; otherwise it is locked.

© 2018 Microchip Technology Inc.

DS40002025A-page 16

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