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FIDO2 security key company releases hardware that's open source and uses Rust

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Re: FIDO2 security key company releases hardware that's open source and uses Rust

#2
I'm still curious how the key is tamper resistent when filling it with transparent epoxy. I asked when the article was published on lobste.rs but never got an answer. It seems to me it should be fairly easy to remove the epoxy and refill after tampering.

I should probably email them about this at this point, but I think it's weird they haven't explained the "tampering resistent" part in their marketing material in any detail.

Re: FIDO2 security key company releases hardware that's open source and uses Rust

#3
post #2

I'm still curious how the key is tamper resistent when filling it with transparent epoxy. I asked when the article was published on lobste.rs but never got an answer. It seems to me it should be fairly easy to remove the epoxy and refill after tampering. I should probably email them about this at this point, but I think it's weird they haven't explained the "tampering resistent" part in their marketing material in an…

AIUI, Tamper Resistant doesn't mean it's not possible to do, but that it will likely be obvious that tampering was done.

Re: FIDO2 security key company releases hardware that's open source and uses Rust

#4
post #3
post #2

I'm still curious how the key is tamper resistent when filling it with transparent epoxy. I asked when the article was published on lobste.rs but never got an answer. It seems to me it should be fairly easy to remove the epoxy and refill after tampering. I should probably email them about this at this point, but I think it's weird they haven't explained the "tampering resistent" part in their marketing material in an…

AIUI, Tamper Resistant doesn't mean it's not possible to do, but that it will likely be obvious that tampering was done.

Then it would be tamper evident, not resistent?

Re: FIDO2 security key company releases hardware that's open source and uses Rust

#5
post #2

I'm still curious how the key is tamper resistent when filling it with transparent epoxy. I asked when the article was published on lobste.rs but never got an answer. It seems to me it should be fairly easy to remove the epoxy and refill after tampering. I should probably email them about this at this point, but I think it's weird they haven't explained the "tampering resistent" part in their marketing material in an…

The epoxy can't be physically removed without great risk of ripping off the electronics on the underlying circuit.

The epoxy can be chemically dissolved, but would deteriorate the outside of the device as well. It the epoxy isn't completely cleaned out, then refilling it with new epoxy would look messy. With great care and skill, it could be done with little damage, but would be time consuming.

Re: FIDO2 security key company releases hardware that's open source and uses Rust

#6
post #4
post #3

Earlier quoted context omitted.

AIUI, Tamper Resistant doesn't mean it's not possible to do, but that it will likely be obvious that tampering was done.

Then it would be tamper evident, not resistent?

Water resistant means some resistance to water. Water proof means full resistance to water. And that is a standard term that has been in use for decades to describe watches, tents, jackets, etc. When I read tamper resistant, I imagine the tamper equivalent of water resistant.

Re: FIDO2 security key company releases hardware that's open source and uses Rust

#7
post #4
post #3

Earlier quoted context omitted.

AIUI, Tamper Resistant doesn't mean it's not possible to do, but that it will likely be obvious that tampering was done.

Then it would be tamper evident, not resistent?

Tamper evident is the correct description of what the parent comment is talking about. You can Google “tamper evident stickers” to see it’s how the phrase is widely used. I would say the epoxy in question is both tamper resistant and evident though. Because it’s both difficult to remove and you’d risk breaking the device if you tried it, and those seem like obvious tamper resistance controls to me.

Re: FIDO2 security key company releases hardware that's open source and uses Rust

#8
post #2

I'm still curious how the key is tamper resistent when filling it with transparent epoxy. I asked when the article was published on lobste.rs but never got an answer. It seems to me it should be fairly easy to remove the epoxy and refill after tampering. I should probably email them about this at this point, but I think it's weird they haven't explained the "tampering resistent" part in their marketing material in an…

FWIW, their choice of microcontroller (LPC55s, which is a Cortex-M33 w/ crypto peripherals and TrustZone) doesn't seem completely terrible.

There's still a lot of things that need to go right for the whole system to be secure, but "everything happens inside one chip, and we cover it in epoxy" seems pretty reasonable. If you can get rid of the epoxy, the only tampering I'd be worried about is removing capacitors for power supply glitching. Power analysis can still be done on an uncompromised device via the USB port (capacitors will make this harder, but may not rule it out).

To go beyond this, you'd probably need to decap the chip. I haven't seen anything about an active die shield in the documentation for this chip, but we're now well beyond the scope of epoxy tamper resistance.

Edit: No die shield, but apparently "cryptographically sensitive" signals and bits have additional out-of-band signals and bits to make shenanigans more difficult. Certainly not perfect, but "not completely terrible" seems like a fair assessment.

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