6079 - MachXO3D: Why does the device could boot whether public key is programed or erased given that ECDSA authentication function is used?

6079 - MachXO3D: Why does the device could boot whether public key is programed or erased given that ECDSA authentication function is used?

MachXO3D's configuration image authentication during programming or boot does have flexible authentication support as stated below:
1. Authenticate during programming = secure + fast boot
2. Pre-authenticaion = secure + slower boot time
3. No authentication = fast boot and fast programming.
Erasing the public key is as good as no authentication and can be use with unsigned bitstream. Thus, XO3D can still boot up if we erase the public key.