No backdoor? Who are people try to kid and lie to? That's a whole "backdoor-OS". This XTRA-service runs in a secret OS "AMSS". It's like Intel's ME (even higher level access than the BIOS/UEFI) and it's painfully clear that's the same with qualcomm. Intel's ME runs on the PC's 5 V psu and does not even need the PC to be active. The same here for Qualcomms secret OS. Just another (of the countless) other backdoors for the criminal and spying scum of the likes of NSA/CIA/police etc. Painfully clear since Snowden what is going on. As the Arpanet, ahem, Internet, smartphones were created with the aim to be spying bugs. Thanks Nitrokey to make a change!