mjg59

94 ms·

541.
by mjg59 4y ago
> systems without IME exist Not if you're buying Intel, they don't. The IME reads the HAP bit during boot, and if that's set will set its state to disabled, but it's still there and you're still relying on the so
542.
by mjg59 4y ago
If an attacker has arbitrary code execution as a user with sudo access (ie, basically any developer system), then the user/root distinction is basically meaningless.
543.
by mjg59 4y ago
The two main protections are requiring multiple signoffs (for landing code) and requiring proof of physical presence (for various things, including any sort of access to prod). Having code exec on a large number of systems means the first i
544.
by mjg59 4y ago
So, uh, don't update the firmware? There's no need for them to backdoor the CPU via the PSP when they could just do it via a microcode update.
545.
by mjg59 4y ago
The PSP is in the CPU, not the motherboard chipset, and doesn't have any access to the network. You can't get commands to it bypassing the main CPU.
546.
by mjg59 4y ago
If you don't trust the manufacturer of your CPU, how do you trust any of the software running on that CPU?
547.
by mjg59 4y ago
Which numbers are you using for that?
548.
by mjg59 4y ago
Having worked with several highly skilled engineers who went to Apple - no, it doesn't.
549.
by mjg59 4y ago
General Apple policy is that employees can't contribute to any open source project without explicit permission, which is very rarely granted (which is why Apple's not on my list of potential employers)
550.
by mjg59 4y ago
The usual way HTTPS client auth works is to issue some sort of persistent access token that then ends up sitting on the filesystem without any sort of additional protection, or alternatively to just fall back to username and password withou
551.
by mjg59 4y ago
Getting a cert requires someone to either compromise the primary DNS server for the domain, or to compromise DNS in multiple independent locations to serve consistent false answers to the probes. It's true that much of the TLS ecosyste
552.
by mjg59 4y ago
SSH's key management in general doesn't depend on DNS being trustworthy, and I'm not sure that solving it by asserting that DNS is trustworthy is a great thing.
553.
by mjg59 4y ago
I can't say in the general sense, but with GCP you can retrieve the EKpub of a VM's TPM via the control plane, and then use https://github.com/google/go-attestation to verify that an application key is associ
554.
by mjg59 4y ago
To be clear, I'm not suggesting trusting the certificate itself - I'm suggesting trusting the signing CA from the certificate, and so also trusting any future certificates for the same host signed by the same CA
555.
by mjg59 4y ago
Thanks! That's hugely helpful - everything I could find myself seemed to be an order of magnitude or so slower than that (and they support ecdsa, too, so I can't even object on the basis of algorithmic support). With hindsight my
556.
by mjg59 4y ago
Wrote my thoughts on this up in some more detail at https://mjg59.dreamwidth.org/65874.html
557.
by mjg59 4y ago
Clock skew unfortunately makes that scale a little impractical, but yeah it would be great to have mechanisms to delegate endpoint certificate issuance to much shorter timescales
558.
by mjg59 4y ago
> The same ones that terminate TLS for millions. Which ones? > Also you can scale horizontally For SSH? Only by having the same private key in all of them, which means it's still around somewhere. > or only use the HSM as a CA
559.
by mjg59 4y ago
Which HSM are you looking at that would be able to handle the required number of transactions per second?
560.
by mjg59 4y ago
In an ideal world this could be avoided by using SSH certificates - an assertion by a trusted party that the key presented by an SSH server is legitimate. The signer of those certificates could be in an HSM, ensuring that the private keys c
561.
by mjg59 4y ago
It's not really so much that Secretive doesn't support RSA keys, it's that the SE doesn't
562.
by mjg59 4y ago
Not directly - you can use CryptoTokenKit to bind SE keys into the keychain as if they were a smartcard, but there's no shipped tooling for that.
563.
by mjg59 4y ago
Secretive has to function as both a key generation utility and an SSH agent because of a restriction in Apple's Secure Enclave functionality - only the app that generates a key is allowed to use it. There's actually a workaround f
564.
by mjg59 4y ago
Apple actually made this much harder than it should be by special-casing P256 ECDSA in their build of libressl, which means trying to use it with PKCS#11 breaks: https://mjg59.dreamwidth.org/64968.html . The approach Secret
565.
by mjg59 4y ago
Using the Secure Enclave allows you to tie use of the key to biometric auth (which also serves as proof of physical presence). Even if someone compromises your system, they can't SSH as you without tricking you into mashing touchID.
566.
by mjg59 4y ago
Check /sys/class/powercap - if you have some RAPL entries there you can set the maximum power draw of the CPU. But in general if you have a fixed workload (ie, your system wants to do a certain amount of work, not use a certa
567.
by mjg59 4y ago
Oh yeah the fact that a given laptop has a given CPU certainly doesn't mean that it's going to run at the same speed as another laptop with the same CPU, and it's unfortunate that manufacturers don't tend to give users t
568.
by mjg59 4y ago
IEC 62368-1 places an upper bound on the temperature of materials in electronic devices that are likely to come into contact with users' skin, and that's incorporated into EU regulations[1]. You have two ways to achieve that - add
569.
by mjg59 4y ago
Yes. And if you run thermald with the adaptive policy enabled, you shouldn't see any benefit from throttled. It's possible that you will, but if so that's likely a bug.
570.
by mjg59 4y ago
What? No, it isn't. It's about something that only affects Ultrabook-style devices, and it's extremely clear that it's not to hit a marketing target because if you run Windows the drivers disable the PL1/2 limitatio

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