&gt; If you have a secure enclave within the device, then any hardware which has a direct connection to that secure enclave must be authenticated.<p>Consider reading the description of iOS security features linked somewhere in this thread.<p>Because what you are describing is a disaster, not security. If some off-chip sensor had access to fingerprint data or crypto keys, anybody capable of installing such chip would also be able to simply dump all the data himself in the comfort of his lab.