5.2.2.2 Public Key Generation

If the slot has been so configured, the ECC public key can be regenerated from a stored ECC private key and output on the bus. In addition, if so desired, a public key digest can also be generated and stored in TempKey at the same time.

For the ATECC608A-TNGLoRaWAN, the public key can be generated from the stored private key in Slot 1. Optional digest generation is also allowed.

Table 5-44. Input Parameters - Public Key Generation

Opcode
(1 Byte)

Mode
(1 Byte)

KeyID
(2 Bytes)

OtherData
(0 Bytes)

Description
0x400x000x00 0[Slot]—Public key generated and output on the bus
0x400x080x00 0[Slot]—
  • Public key generated and output on the bus
  • Public key digest generated and stored in TempKey
Table 5-45. Output Response - Public Key Generation
NameSizeResponse
Response1 byteECC Fault code if command fails
64 bytesPublic keys X and Y coordinate the command’s success

Public Key Digest Generation

A SHA256 Hash is performed over 128 bytes to generate a digest from the public key.

32 bytes
1 byte
1 byte
2 bytes
1 byte
2 bytes
25 bytes
64 bytes

TempKey
OpCode
Param1
Param2
SN[8]
SN[0:1]
Zeros
X and Y coordinates of the public key