Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Lennart Poettering, Christian Brauner founded a new company

amutable.com

Post reply on HN
Print view View original

331–340 of 770 posts

Re: Lennart Poettering, Christian Brauner founded a new company

#331

Post by coppsilgold »

Remote attestation only works because your CPU's secure enclave has a private key burned-in (fused) into it at the factory. It is then provisioned with a digital certificate for its public key by the manufacturer.

Every time you perform an attestation the public key (and certificate) is divulged which makes it a unique identifier, and one that can be traced to the point of sale - and when buying a used device, a point of resale as the new owner can be linked to the old one.

They make an effort to increase privacy by using intermediaries to convert the identifier to an ephemeral one, and use the ephemeral identifier as the attestation key.

This does not change the fact that if the party you are attesting to gets together with the intermediary they will unmask you. If they log the attestations and the EK->AIK conversions, the database can be used to unmask you in the future.

Also note that nothing can prevent you from forging attestations if you source a private-public key pair and a valid certificate, either by extracting them from a compromised device or with help from an insider at the factory. DRM systems tend to be separate from the remote attestation ones but the principles are virtually identical. Some pirate content producers do their deeds with compromised DRM private keys.

Re: Lennart Poettering, Christian Brauner founded a new company

#332

Post by Sophira »

ahartmetz wrote: post #300
bee_rider wrote: post #279

Earlier quoted context omitted.

PipeWire is like 10 years newer than PulseAudio. It probably had a chance to learn some lessons! IIRC before PulseAudio we had to mess around with ALSA directly (memory hazy, it was a while ago). It could be a bit of a pain.

PipeWire was also made by a guy with a lot of multimedia experience (GStreamer). ALSA was kind of OK after mixing was enabled by default and if you didn't need to switch outputs of a running application between anything but internal speakers and headphones (which worked basically in hardware). With any additional devices that you could add and remove, ALSA became a more serious limitation, depending. You could usuall…

> Not sure if it ever worked with Bluetooth.

It does, with the help of BlueALSA[0].

[0] https://github.com/arkq/bluez-alsa

Re: Lennart Poettering, Christian Brauner founded a new company

#333

Post by warkdarrior »

coppsilgold wrote: post #331

Remote attestation only works because your CPU's secure enclave has a private key burned-in (fused) into it at the factory. It is then provisioned with a digital certificate for its public key by the manufacturer. Every time you perform an attestation the public key (and certificate) is divulged which makes it a unique identifier, and one that can be traced to the point of sale - and when buying a used device, a poin…

Anonymous-attestation protocols are well known in cryptography, and some are standardized: https://en.wikipedia.org/wiki/Direct_Anonymous_Attestation

Re: Lennart Poettering, Christian Brauner founded a new company

#334

Post by Nextgrid »

Thaxll wrote: post #75

I always wondered how this works in practice for "real time" use cases because we've seen with secure boot + tpm that we can attest that the boot was genuine at some point in the past, what about modifications that can happen after that?

A full trusted boot chain allows you to use a reboot to revert back to a trusted state after suspected runtime compromise.

Re: Lennart Poettering, Christian Brauner founded a new company

#335

Post by Sophira »

Brian_K_White wrote: post #284
dijit wrote: post #170

Earlier quoted context omitted.

The trick is the same: use a popular linux distribution and don't fight the kinks. The people who had no issues with Pulseaudio; used a mainstream distribution. Those distributions did the heavy lifting of making sure stuff fit together in a cohesive way. SystemD is very opinionated, so you'd assume it wouldn't have the same results, but it does.. if you use a popular distro then they've done a lot of the hard work t…

"The trick is the same: use a popular linux distribution and don't fight the kinks." I believe that you are genuinely being sincere here, thinking this is good advice. But this is an absolutely terrible philosophy. This statement is ignorant as well as inconsiderate. (again, I do believbe you don't intend to be inconsiderate consciously, that is just the result.) It's ignorant of history and inconsiderate of everyone…

> Go back a few years and this same logic says "The trick is, just use Windows and do whatever it wants and don't fight."

This is basically exactly what I saw people saying in Windows subreddits. There's one post that particularly sticks out in my memory[0] that basically had everybody telling the OP to just not make any of the changes that they wanted to make. The advice seemed to revolve around adapting to the OS rather than adapting the OS to you, and it made me sad at the time.

[0] https://www.reddit.com/r/Windows10/comments/hehrqe/what_are_...

Re: Lennart Poettering, Christian Brauner founded a new company

#336

Post by coppsilgold »

warkdarrior wrote: post #333
coppsilgold wrote: post #331

Remote attestation only works because your CPU's secure enclave has a private key burned-in (fused) into it at the factory. It is then provisioned with a digital certificate for its public key by the manufacturer. Every time you perform an attestation the public key (and certificate) is divulged which makes it a unique identifier, and one that can be traced to the point of sale - and when buying a used device, a poin…

Anonymous-attestation protocols are well known in cryptography, and some are standardized: https://en.wikipedia.org/wiki/Direct_Anonymous_Attestation

> Anonymous-attestation protocols are well known in cryptography, and some are standardized: https://en.wikipedia.org/wiki/Direct_Anonymous_Attestation

Which does exactly what I said. Full zero knowledge attestation isn't practical as a single compromised key would give rise to a service that would serve everyone.

  The solution first adopted by the TCG (TPM specification v1.1) required a trusted third-party, namely a privacy certificate authority (privacy CA). Each TPM has an embedded RSA key pair called an Endorsement Key (EK) which the privacy CA is assumed to know. In order to attest the TPM generates a second RSA key pair called an Attestation Identity Key (AIK). It sends the public AIK, signed by EK, to the privacy CA who checks its validity and issues a certificate for the AIK. (For this to work, either a) the privacy CA must know the TPM's public EK a priori, or b) the TPM's manufacturer must have provided an endorsement certificate.) The host/TPM is now able to authenticate itself with respect to the certificate. This approach permits two possibilities to detecting rogue TPMs: firstly the privacy CA should maintain a list of TPMs identified by their EK known to be rogue and reject requests from them, secondly if a privacy CA receives too many requests from a particular TPM it may reject them and blocklist the TPMs EK. The number of permitted requests should be subject to a risk management exercise. This solution is problematic since the privacy CA must take part in every transaction and thus must provide high availability whilst remaining secure. Furthermore, privacy requirements may be violated if the privacy CA and verifier collude. Although the latter issue can probably be resolved using blind signatures, the first remains.
AFAIK no one uses blind signatures. It would enable the formation of commercial attestation farms.

Re: Lennart Poettering, Christian Brauner founded a new company

#337

Post by stogot »

coppsilgold wrote: post #331

Remote attestation only works because your CPU's secure enclave has a private key burned-in (fused) into it at the factory. It is then provisioned with a digital certificate for its public key by the manufacturer. Every time you perform an attestation the public key (and certificate) is divulged which makes it a unique identifier, and one that can be traced to the point of sale - and when buying a used device, a poin…

I’m not sure I understand the threat model for this. Why would I need to worry about my enclave being identifiable? Or is this a business use case?

Or why buy used devices if this is a risk?

Re: Lennart Poettering, Christian Brauner founded a new company

#338

Post by rsync »

direwolf20 wrote: post #303
jacquesm wrote: post #287

Earlier quoted context omitted.

I think at some point we will see a steep increase in value of old hardware that can still run unsigned binaries.

It won't be able to interact with any online services like Google or Hacker News.

You will always be able to interact with rsync.net …

… and the warrant canary we publish every Monday morning.

Re: Lennart Poettering, Christian Brauner founded a new company

#339

Post by charcircuit »

Fischgericht wrote: post #231
Nextgrid wrote: post #98

Earlier quoted context omitted.

Secure Boot only extends the chain of trust from your firmware down the first UEFI binary it loads. Currently SB is effectively useless because it will at best authenticate your kernel but the initrd and subsequent userspace (including programs that run as root) are unverified and can be replaced by malicious alternatives. Secure Boot as it stands right now in the Linux world is effectively an annoyance that’s only t…

Yes, "just as secure as proprietary OSes" who due to failed signature verification are no longer able to start notepad.exe. I think you might want to go re-read the last ~6 months of IT news in regards of "secure proprietary OSes".

Just because OpenSSL had a CVE posted about today, that didn't mean we should go back to use HTTP for the web.

Re: Lennart Poettering, Christian Brauner founded a new company

#340

Post by CGMthrowaway »

stogot wrote: post #337
coppsilgold wrote: post #331

Remote attestation only works because your CPU's secure enclave has a private key burned-in (fused) into it at the factory. It is then provisioned with a digital certificate for its public key by the manufacturer. Every time you perform an attestation the public key (and certificate) is divulged which makes it a unique identifier, and one that can be traced to the point of sale - and when buying a used device, a poin…

I’m not sure I understand the threat model for this. Why would I need to worry about my enclave being identifiable? Or is this a business use case? Or why buy used devices if this is a risk?

For most individuals it usually doesn’t matter. It might matter if you have an adversary, e.g. you are a journalist crossing borders, a researcher in a sanctioned country, or an organization trying to avoid cross‑tenant linkage

Remote attestation shifts trust from user-controlled software to manufacturer‑controlled hardware identity.

It's a gun with a serial number. The Fast and Furious scandal of the Obama years was traced and proven with this kind of thing

Post reply on HN