ATECC SIGN instruction

This command asks the SpringCore device to perform an ECDSA signature , using its ATECC Secure Element.

This instruction is not available and will return an error if the device does not feature an ATECC Secure Element.

The private key must have been loaded earlier using the ATECC LOAD KEY instruction.

Field	Value	Remark
CLA	`FF`
INS	`F9`
P1	`EC`	ECDSA signature
P2	Key Index	`00` to `0D`
Lc	`20`	DataIn is the SHA256 of the message to be signed. Therefore, its length is forced to 32 bytes
DataIn	Input hash	SHA256 of the message to be signed
Le	`00`

Response

Field	Value	Remark
DataOut	Computed signature	70, 71 or 72 bytes
SW	`9000` on success	Other values are documented in Status Words