TDA4VM-Q1: Concept clarification for HS device with dummy key

Hi Gibbs,

Gibbs Shih said:

Basically , device type "D" already include "TI dummy key" in chip, so customer can "encrypt their software" with "TI dummy key" directly, and they do not need to burning "TI dummy key" into efuse in TDA4.

Is it correct?

Correct, 

Gibbs Shih said:

Device type "D"  "also" support customer's encryption key programming into e-fuse, but it is also "non-reversible".  programming just only one time!

Is it correct?

You can't fuse any other keys in the customer area once the device got converted to HS-SE, SMEK fused on the HS-SE TI dummy devices are TI dummy keys only and we need to use those keys to encrypt the image.

Gibbs Shih said:

If customer have some problems with their customized key after key-writer programming. (for example, lost their private/public key information),  they can also return to use "TI dummy key" for development?

Purpose of dummy keys devices is that if the customer dont want to burn the keys on the devices but still want to do the development on the HS-SE devices during their initial development phase, they can use TI dummy devices.

Eventually customer will use HS-SE devices fused with their own keys.

Regards
Diwakar