I <i>think</i> it does have non-volatile on-chip storage, which is used to store a randomly generated key that is encrypted with the key derived from the PIN and UID. It is that randomly generated key that is used to encrypt flash data.<p>I cannot find documentation to verify this. I presume the people down voting you do, but unfortunately they&#x27;ve chosen to down vote instead of being useful and posting a link. (The only link I&#x27;ve seen is for A7 and later systems)