ATSHA204A datasheet(45/93 Pages) MICROCHIP

45 / 93 page

In most but not all cases, failing commands return relatively quickly, often well before the typical execution

time.

Table 8-4. Command Opcodes, Short Descriptions and Execution Times

Command

Opcode Description

Typ. Exec.

Time(1), ms

Max. Exec.

Time(2), ms

DeriveKey

0x1C

Derive a target key value from the target or parent key.

DevRev

0x30

Return device revision information.

0.4

GenDig

0x15

Generate a data protection digest from a random or input

seed and a key.

HMAC

0x11

Calculate response from key and other internal data using

HMAC/SHA-256.

CheckMac

0x28

Verify a MAC calculated on another Microchip

CryptoAuthentication device.

Lock

0x17

Prevent further modifications to a zone of the device.

MAC

0x08

Calculate response from key and other internal data using

SHA-256.

Nonce

0x16

Generate a 32-byte random number and an internally stored

nonce.

Pause

0x01

Selectively put just one device on a shared bus into the idle

state.

0.4

Random

0x1B

Generate a random number.

Read

0x02

Read four bytes from the device, with or without

authentication and encryption.

0.4

SHA

0x47

Calculate a SHA256 digest for any system purpose.

UpdateExtra

0x20

Update bytes 84 or 85 within the Configuration zone after

the Configuration zone is locked.

Write

0x12

Write 4 or 32 bytes to the device, with or without

authentication and encryption.

Note:

Typical execution times are representative of the duration to execute the command assuming no

error conditions, fastest mode setting, no optional internal actions such as limited use keys and

favorable environmental conditions. For best performance, delay for this interval and then start

polling to determine actual command completion.

Maximum execution times are representative of the longest duration of a successful command

execution with all mode and internal actions enabled under extended statistical and environmental

conditions. Execution time may extend beyond these values in extreme situations.

8.5.3

Zone Encoding

The value in Param1 for both the Read command and the Write command controls which zone the

command accesses. See Section Configuration Zone Locking to obtain more information on what

controls the “locked” and “unlocked” states for each zone. All other zone values are reserved and should

not be used.

ATSHA204A

Security Commands

DS40002025A-page 45

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