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

Tillitis Key – Mullvad spin-off inspired by measured boot and DICE

tillitis.se

Post reply on HN
Print view View original

41–50 of 123 posts

Re: Tillitis Key – Mullvad spin-off inspired by measured boot and DICE

#41

Post by kfreds »

jeroenhd wrote: post #26

I'm not sure what problem this solves. I see per-application keys based on the hash of the application, but wouldn't this prevent updates of those applications without key loss? It's clear to me that this device can be used for _some_ kind of cryptographic operation/verification mechanism, but I'm at a loss for what problem this is actually designed to solve. What's the practical application of this key?

Tillitis Key’s design encourages developers to experiment with new security key applications and models in a way that makes adoption easier and less risky for end-users.

You can read more on tillitis.se or in the comment I made below.

Tillitis Key will allow you to chain-load applications. This means that you could have a thin loader which does code signing verification of the next application stage, and hand off the secret to it. Basically it's a trust policy that defines under what circumstances the next application stage gets the secret.

Another trust policy the loader could have is requiring m-of-n code signatures, or perhaps that as well as transparency log inclusion. Check out sigsum.org.

Re: Tillitis Key – Mullvad spin-off inspired by measured boot and DICE

#43

Post by ptman »

FredFS456 wrote: post #10
PhilippGille wrote: post #5

> Something that makes the key unique is the fact that both its software and hardware are open source Aren't SoloKeys [1] also open hardware and software? Or is the Tillitis key more general purpose and thus not in the same category? [1] https://solokeys.com/

My understanding is that it's both a more general platform (targeting more than 2FA) and also uses an FPGA running open-source code, so that the "secure enclave" functionality can be inspected and found to be secure, rather than just trusting NXP/ARM's chip as SoloKeys have done.

FTR SoloKeys targets FIDO2, not just U2F

Re: Tillitis Key – Mullvad spin-off inspired by measured boot and DICE

#44

Post by riedel »

byyll wrote: post #23
LibertyBeta wrote: post #15

Earlier quoted context omitted.

So Solokey V2. Not that I'm complaining by the way. Any open competition to yubikey is a win in my book.

I really dislike how "Yubikey" is being used in many places as a name for U2F and FIDO2.

This is because the fido2 libraries follows a lot of defacto standardisation: either to match yubikey or windows hello as the only real implementations in the wild. Fido2 ctap extensions would support all the use cases of the new device except you won't be able to use them e.g. in windows because vendors are ignorant about all the openess to push their own agenda.

Re: Tillitis Key – Mullvad spin-off inspired by measured boot and DICE

#45

Post by jffry »

byyll wrote: post #23
LibertyBeta wrote: post #15

Earlier quoted context omitted.

So Solokey V2. Not that I'm complaining by the way. Any open competition to yubikey is a win in my book.

I really dislike how "Yubikey" is being used in many places as a name for U2F and FIDO2.

It's the same as "Google Authenticator" being used instead of TOTP. I think it's reasonable for apps' documentation to meet users on their turf to aid understanding.

Re: Tillitis Key – Mullvad spin-off inspired by measured boot and DICE

#46

Post by Semaphor »

jeroenhd wrote: post #26

I'm not sure what problem this solves. I see per-application keys based on the hash of the application, but wouldn't this prevent updates of those applications without key loss? It's clear to me that this device can be used for _some_ kind of cryptographic operation/verification mechanism, but I'm at a loss for what problem this is actually designed to solve. What's the practical application of this key?

This comment explains it: https://news.ycombinator.com/item?id=32897307

Re: Tillitis Key – Mullvad spin-off inspired by measured boot and DICE

#47

Post by layer8 »

JoachimS wrote: post #21
ldng wrote: post #17

Earlier quoted context omitted.

It is an FPGA, fully open both at software and hardware level. So quite a bit more futurproof, inspectable and upgradable than a yubikey.

(For full disclosure I am the primary FPGA designer of TillitisKey.) It also perform a measurement of the application being loaded. And the measurement together with the Unique Device Secret (UDS) will generate the primary secret applications can use to derive keys etc it needs. This means that you can verify the application integrity. This is very close to, inspired by DICE: https://www.microsoft.com/en-us/research/…

What exactly is the “measurement”? A hash of the application code?

Re: Tillitis Key – Mullvad spin-off inspired by measured boot and DICE

#48

Post by michaelt »

xani_ wrote: post #38
michaelt wrote: post #29

Earlier quoted context omitted.

According to [1] > It offers both security and flexibility by being end-user programmable while also preventing applications loaded onto the device from knowing each other’s secrets. During use firmware on Tillitis Key derives a unique key for each application it runs by measuring it before execution. This is done by combining an application’s hash value with a unique per device secret. Applications are loaded onto t…

* If you save secrets with application A, then install evil application B, it can't access the secrets from A. * And if you revert back to A, those saved secrets will still be there. What stops app B from pretending it's an app A ?

Something like 'Secure Boot' / 'Measured Boot' on modern PCs, I imagine.

A bootloader will checksum the current application before running it, checking its digital signatures and version and whatnot, and deriving an encryption key based on that.

Re: Tillitis Key – Mullvad spin-off inspired by measured boot and DICE

#49

Post by kfreds »

xani_ wrote: post #38
michaelt wrote: post #29

Earlier quoted context omitted.

According to [1] > It offers both security and flexibility by being end-user programmable while also preventing applications loaded onto the device from knowing each other’s secrets. During use firmware on Tillitis Key derives a unique key for each application it runs by measuring it before execution. This is done by combining an application’s hash value with a unique per device secret. Applications are loaded onto t…

* If you save secrets with application A, then install evil application B, it can't access the secrets from A. * And if you revert back to A, those saved secrets will still be there. What stops app B from pretending it's an app A ?

1. The hardware contains a UDS (unique per device secret) which can only be read once per boot cycle.

2. Firmware in ROM does unconditional measurement of the first mutable boot stage, which is loaded from the host, over USB.

The KDF used for measurement is Blake2s(UDS, Blake2s(application), USS).

Note that when I say hardware I mean FPGA hardware design.

Re: Tillitis Key – Mullvad spin-off inspired by measured boot and DICE

#50

Post by timando »

xani_ wrote: post #38
michaelt wrote: post #29

Earlier quoted context omitted.

According to [1] > It offers both security and flexibility by being end-user programmable while also preventing applications loaded onto the device from knowing each other’s secrets. During use firmware on Tillitis Key derives a unique key for each application it runs by measuring it before execution. This is done by combining an application’s hash value with a unique per device secret. Applications are loaded onto t…

* If you save secrets with application A, then install evil application B, it can't access the secrets from A. * And if you revert back to A, those saved secrets will still be there. What stops app B from pretending it's an app A ?

It would have to hash to the same value as app A
Post reply on HN