How do you not feel embarrassed after typing that edit. The iPhone flair also gives it a special kind of irony. The timing of me finding this post 5 years later right when there’s a discovery of the NSA backdoor in Apple A12-A16 chips is impeccable.
How do you not feel embarrassed after typing that edit. The iPhone flair also gives it a special kind of irony. The timing of me finding this post 5 years later right when there’s a discovery of the NSA backdoor in Apple A12-A16 chips is impeccable.
I’ve only skimmed it but it looked like this was based on unusual peripherals outside the ARM core, rather than something standard. Have you read deeper into it?
Kasperskys thing said it was in the gpu address space. It doesn’t need to be in that space, since it’s afaik just a hardware cipher. You are correct though, the gpu is a weird peripheral that’s not part of the cpu core.
E: it’s worth saying outright that almost every soc or cisc processor has a gpu built in so it’s not like the weird peripheral in question is all that weird or even really much of a peripheral, considering it’s built into the device and these chips are designed to handle user input. The qualcoms in Samsung phones for example have had built in gpus since 2008. Intel core processors have had built in gpus in most since westmere in 2010.
E2: talking with someone about this I realized something important isn’t obvious at first glance: the peripheral in gpu address space status of the hardware backdoor doesn’t matter in the slightest because we don’t know where on the actual silicon wafer it is. The a series chips, and all arm chips in stuff nowadays, have the gpu and a bunch of other peripherals built into them, all on the same die. The only reason the backdoor is being talked about like a peripheral is because it’s doing memory mapped I/o. The only reason it’s being talked about with the gpu is because it’s in the address space reserved for the gpu. The a series, and all normal mobile arm processors, have a memory management unit that figures out where some 64bit hex address actually goes to or if it goes at all. I could put on my sicko hat and have stuff located smack in the middle of the floating point unit and it would work fine and you’d be none the wiser because all your requests go through the mmu and bear no relationship to the physical location on the silicon die and I’d do it again!
There is no evidence I’ve seen that this little 20 bit cypher, a drop in the ocean of transistors that is a modern microprocessor, requires a gpu or even needs to be outside the official arm stuff.
We would never know because it’s one memory address in literally 18 quintillion addresses in the 64 bit space.