Page 33
13. Hardware Security
13.1 Factory Generation of Device Key
Each device has a private key and associated certificate which is used to authenticate itself when
initiating communications. This private key is generated in the factory, and so is the corresponding
vendor certificate. This capability necessary in order to support large scale plug and play
deployments.
This device key is stored on the Sprint TREBL to allow it to authenticate to the network. If the private
key is compromised, then the device can be masq
ueraded by an attacker towards the operator’s core
network. Therefore, it is stored in an encrypted form.
In later releases a device-specific key will be introduced, this is a random number blown into on-SoC
eFuses during manufacture. This offers two points of additional protection namely: the key is not
discoverable by decompiling the code (an attacker will need to run code on the device in order to read
the eFuses); and the key can only be used to obtain the private key of a single device (because each
encryption key is unique).
13.2 eSIM
The system provides an embedded SIM (eSIM) to the board instead of using a removable SIM; this
removes the temptation to steal the SIM. Additionally, the operator can ensure that these SIMs can
only be used with the Relay APN, which would make them unusable with an ordinary mobile phone
(because relay traffic uses nested GTP-U tunnels).
