How to store public key into device Flash

The public key is used  by Second Stage Bootloader to verify Apploder and Application firmware. This key is stored into User Mode location on the chip. It is flashed into topmost page of the main flash and not accessible from the user application. To store the public key on the device use the following command: 

commander flash –-tokengroup znet –-tokenfile signing-key-tokens.txt

The command above should be launched from the folder where the signing-key-tokens.txt file is located.

For strong security, public keys need to be protected from accidental or intentional modification. This protection can be accomplished via hardware support, such as storing the keys in an immutable memory such as OTP or a locked flash page, or the key can be crypto-graphically authenticated prior to it being used.

By default, the public key is stored in the last page of main flash memory. In order to secure this key, the flash page containing the key must be locked in order to prevent software from being able to modify the key. This flash page protection operation can be performed either in the Second Stage Bootloader or in the Application.

As an alternative to protecting the public key via hardware, it can be protected using cryptographic authentication. The method using cryptographic authentication using certificates represents the strongest and most flexible security solution.

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