Data Zone - Clear Text Write

Standard Clear Text Writes

Clear text writes to Data zone slots are only possible for slots so configured provided they have not been SlotLocked. Note that any given slot may allow for more than one block of data to be written to it based on the size of the slot. 4 or 32-byte writes are permissible for any block within a slot provided that slot is not secret. For secret slots only 32 byte writes are permitted. The last block of any slot will not be 32 bytes. This can still be written as a 32-byte write and the additional bytes need to be padded with zeros. For the ATECC608A-TFLXTLS device, Slots 6, 8-9, 13 and 15 can be written as clear text.

Invalidated Public Key Writes

Since ECC public keys are not secret values, they may be directly written as ClearText by the write command. If the key requires validation prior to use then the key cannot be overwritten without first invalidating the key. The Invalidate mode of the Verify command must first be used to invalidate the PublicKey prior to trying to write this key with the write command.

For the ATECC608A-TFLXTLS device, Slot 14 contains a validated public key.

The input parameters for a standard clear text write and the invalidated public key write are identical once the public key has been invalidated.

Table 1. Clear Text Write Input Parameters

Opcode
(1 Byte)

Mode
(1 Byte)

Address
(2 Bytes)

Data
(4 or 32 Bytes)

Description
0x12 0x02 See Section Address Encoding 4 bytes 4-byte write
0x82 See Section Address Encoding 32 bytes 32-byte write
Table 2. Clear Text Write Output Response
Name Size Description
Response 1 byte If successful, it will return a value of 0x00. If unsuccessful, then an error code will be returned.