eamann
Joined 14 years ago
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595
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330
Member since
Nov 5
[ my public key: https://keybase.io/eamann; my proof: https://keybase.io/eamann/sigs/WsUMibMJa0bfIyDDLBWSjF3TvVvJP3EqF3Y-1EZz7zc ]
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Comment · 7 months ago
It's to protect against the whims of a small set of people.
If one person holds the signing key to do something critical in your system, they're both a single point of failure and a huge security risk all in one. If you distribute that key to, say, 5 different people you've mitigated the single point of failure. But now you have 5 folks who can act potentially unilaterally.
Using a 3 of 5 TSS setup, you've still mitigated the single point of failure (any one or even two folks can go offline and you can still operate) while also protecting against unilateral action. It's a mathematically-enforced version of the "two-man rule." Similar to the way Cloudflare's Red October tool used to work by splitting things between parties: https://blog.cloudflare.com/red-october-cloudflares-open-sou...
Comment · 7 months ago
Oblivious transfer - party A creates two random values (x_0 and x_1) and sends them _both_ to party B.
Party B picks one and uses that to compute future values that are sent back to party A _but without telling party A which of the two values they picked_.
In this example I'm hand-wavey because the production math is complicated and confusing - I took a vastly simplified approach that still works functionally for the demonstration without fully implementing the OT protocol.
> what happens if an owner drops out or you want to introduce a new one? what happens if you want to change the quorum?
In either of those scenarios, assuming you still have quorum, you can regenerate keyshares for the new group for the same public key (and underlying yet unknown private key) by re-running the ceremony with the new participants. Production implementations of the protocol fully flesh this out.
> traditional authentication ...
I wouldn't use TSS in that setup. Traditional auth + MFA is more than adequate. The better use case would be where you have a group that needs to demonstrate consensus (like governance for a programming language, multiple parties involved in signing an application release, or even an HOA that needs to vote on policies). In all of these, you'd take an M of N approach (rather than the simplified 2 of 2) for achieving quorum.
Comment · 7 months ago
You're correct there that proper use means even the owner can't access it. But in a single key scenario they can still act unilaterally. The advantage of TSS is the removal of that level of unilateral action.