Generate OTP Service

Sets up the device to receive a one-time passcode. A 128-bit nonce, NFPGA, is generated and stored in volatile memory for later use in the rest of the protocol. A 128-bit user nonce, NUSER, is supplied by the user.

This service only unlocks the software debug lock SWL_DEBUG.

Table 1. Generate OTP Service Request
System Service Descriptor Bit Field	Value	Description
15:7	MBOXADDR[10:2]	Mailbox address. See Table 2.
6:0	7AH	Generate OTP service command

The following table lists the Generate OTP Service mailbox format.

Table 2. Generate OTP Service Mailbox Format
Offset	Length (bytes)	Parameter	Direction	Description
0	1	KEYMODE	Input	Specifies the key mode used to transport the encrypted passcode. The KEYMODE parameter is not checked for validity until the MATCH OTP service is executed.
4	16	NUSER	Input	Specifies the user nonce, and is supplied by the user.
20	16	NFPGA	Output	The 128-bit nonce, NFPGA, is generated and stored in volatile memory for later use in the rest of the protocol.