"silently"
Everything is done silently and quietly nowadays.
AMD silently removes memory encryption from consumer Ryzen CPUs
81–90 of 225 posts
Re: AMD silently removes memory encryption from consumer Ryzen CPUs
#82I don't know how this works but does this mean if someone gained physical access to your locked running computer, they could gain access to your full encrypted drive and anything saved on disk? My reasoning there is if you used an encrypted drive, the decryption key you type when booting up would be stored in memory for the duration of that boot. This seems alarming because it means if someone broke into your living…
This feature was off by default in all the mobos I've seen. It causes many stability issues, as to my experience. The attack is sophisticated, Mr.Nobody, generally, should not worry about expensive cryogenic attacks - three letter guys would extract your key with a wrench. I mean the change is bad - it undermines already damaged trust, but the "average Joe" is extremely unlikely to be affected directly. There are man…
>It causes many stability issues, as to my experience
In my experience it very much does not, ram instability with this feature indicates a hardware issue same as with ECC.
>Mr.Nobody, generally, should not worry about expensive cryogenic attacks - three letter guys would extract your key with a wrench.
This is disingenuous framing. There exist valid threat models for average people between thieves and three letter agencies. Police forces and organized crime have been known to use ram freezing, the former is not known for wrench attacks. That scenario is only good for hand waving real concerns anyways.
Re: AMD silently removes memory encryption from consumer Ryzen CPUs
#83Earlier quoted context omitted.
Many many people use consumer CPUs for gaming servers.
So reading between the lines, you're saying it's bad for AMD to disable undocumented features because people still might have bought them for those undocumented features, particularly for gaming servers?
Yes.
Re: AMD silently removes memory encryption from consumer Ryzen CPUs
#84Earlier quoted context omitted.
Are you sure? I thought it's just AES without any authentication.
Yes, it's AES with a tweak based on the physical address. It adds some protection from RowHammer and the like because flipping a bit in encrypted memory is catastrophic, while it can be done in a controlled manner if it's not encrypted.
Whether you get controlled bit flip depends on exact encryption mode used. Haven't seen any document with enough technical details on how exactly their encryption scheme works.
Many of traditional block cypher encryption modes do `cypher_text = plain_text ^ block_chypher_output` with the differences being what goes into block cypher input. This means that single bit flip in cypher text maps 1:1 to bit flip in corresponding decrypted block (and sometimes uncontrolled flips in next block). For malleability prevention full protocols would use MAC in addition to encryption. That's not very practical for memory encryption. Ability to use of various chaining modes is limited since you don't want to re encrypt whole ram when single byte changes or otherwise reduce parallelization of ram processing. Only traditional mode which doesn't degrade parallelization is counter mode, but that's fully susceptible to controlled bit flips. Maybe they can use chaining at cache line or cache block level.
This made me think. If the memory controller is already implementing encryption with limited chaining at block level. It wouldn't take much more additional resources to include hardware MAC as well, thus providing much stronger error detection (not correction) capability compared to typical ECC. The fact they aren't advertising it makes me think they aren't doing it, thus using some kind of counter mode variation and thus no extra bitflip protection.
Re: AMD silently removes memory encryption from consumer Ryzen CPUs
#85I don't know how this works but does this mean if someone gained physical access to your locked running computer, they could gain access to your full encrypted drive and anything saved on disk? My reasoning there is if you used an encrypted drive, the decryption key you type when booting up would be stored in memory for the duration of that boot. This seems alarming because it means if someone broke into your living…
This feature was off by default in all the mobos I've seen. It causes many stability issues, as to my experience. The attack is sophisticated, Mr.Nobody, generally, should not worry about expensive cryogenic attacks - three letter guys would extract your key with a wrench. I mean the change is bad - it undermines already damaged trust, but the "average Joe" is extremely unlikely to be affected directly. There are man…
Unless you live in North Korea, China, Russia, UK, France, Australia or Ireland it’s still illegal to coerce or force someone to give up their personal keys or passwords, so this feature is still useful against some law-bound adversaries in free countries.
Re: AMD silently removes memory encryption from consumer Ryzen CPUs
#86Earlier quoted context omitted.
If you ever had to use an iPhone that would just shut off randomly with like 30% battery "remaining", you'd probably be singing a different tune and appreciative your device became somewhat more usable with the changes.
I'd expect the battery charge estimation to be recalibrated to account for the reduced capacity, not the hardware being deliberately hobbled to hide it.
I heard the old batteries, when giving high current would depress voltage long enought to trigger the shutdown, plausibly long enough to mess up the processor if it didn't shut down, but could genuinely give a lower current for a long time, such that rounding the charge down to zero would be harmful. It's easy to argue it's better to keep the phone slower then just shut it down when it can't reliably go fast.
Re: AMD silently removes memory encryption from consumer Ryzen CPUs
#87I'm curious about Denuvo's opinion on that.
denuvo is dead in the water right now, anyways
Re: AMD silently removes memory encryption from consumer Ryzen CPUs
#88I'm curious about Denuvo's opinion on that.
AMD's memory encryption is completely transparent and irrelevant to the OS and its applications hence the transparent in the name.
Re: AMD silently removes memory encryption from consumer Ryzen CPUs
#89[flagged]
Re: AMD silently removes memory encryption from consumer Ryzen CPUs
#90This was never marketed as a feature of the consumer CPUs and if some malignant actor does get physical access to my (consumer) hardware, then them being able to read out bytes through cryo-freezing the RAM really isn't high up on the list of things I'm going to worry about.
This doesn't matter; it's post-sale enshittification... They didn't even wait to make the next model shittier! Also, it probably wasn't the selling point, but it was the baseline of quality, and probably documented online or in manuals. Furthermore, accepting this as normal opens the door to further post-sale enshittification of ALL things. Next thing you know, upgrades here and there are going to degrade the quality…
This is FUD. We have no idea the reason why.
Given it was never marketed, it's possible perhaps despite the feature being exposed it never worked correctly and AMD saw fit to just disable it rather than people get a false sense of security through it.