Why One Key Shouldn't Rule Them All: Threshold Signatures for the Rest of Us • Hacker News Board

Re: Why One Key Shouldn't Rule Them All: Threshold Signatures for the Rest of Us

#21

Post by yammosk » Mon, Mar 23, 2026, 4:26 PM UTC

MattPalmer1086 wrote: post #20

yammosk wrote: post #19

Earlier quoted context omitted.

What secret is controlled by one person? That's just not how businesses manage secrets.

You are not consistent here. When talking about only needing a single signing key you say that is not subject to the whim of one person. When discussing an N-out-of-M scheme, you think that it's just down to the whims of whoever is in that group. That's just not how business manages secrets!

I just don't think that keys would be accessible by only one person in either scenario for any large business. The article suggests this 3/5 key needed system prevents issues but I don't think so in practical terms. My suspicion is it thinks there is only one person per key but I think in any business scenario a team would have access to all of them negating the benefits. I don't think that's inconsistent, perhaps just my misunderstanding of what this proposed.

Re: Why One Key Shouldn't Rule Them All: Threshold Signatures for the Rest of Us

#22

Post by mhluongo » Mon, Mar 23, 2026, 6:55 PM UTC

bob1029 wrote: post #17

mhluongo wrote: post #12

Earlier quoted context omitted.

Again and again, we've seen that HSMs aren't secure against physical access of the device.

Can you point me to an example of a FIPS level 3+ certified device having its private keys compromised due to a defeat of the tamper resistant boundary?

Here are a couple examples of physical access leading to key extraction. You're welcome to be pedantic (those are side channel attacks, they don't defeat the boundary!) but one way or another, physical access wins.

https://www.cl.cam.ac.uk/~rnc1/descrack/ https://ninjalab.io/eucleak/

Re: Why One Key Shouldn't Rule Them All: Threshold Signatures for the Rest of Us

#23

Post by MattPalmer1086 » Mon, Mar 23, 2026, 11:43 PM UTC

yammosk wrote: post #21

MattPalmer1086 wrote: post #20

Earlier quoted context omitted.

You are not consistent here. When talking about only needing a single signing key you say that is not subject to the whim of one person. When discussing an N-out-of-M scheme, you think that it's just down to the whims of whoever is in that group. That's just not how business manages secrets!

I just don't think that keys would be accessible by only one person in either scenario for any large business. The article suggests this 3/5 key needed system prevents issues but I don't think so in practical terms. My suspicion is it thinks there is only one person per key but I think in any business scenario a team would have access to all of them negating the benefits. I don't think that's inconsistent, perhaps ju…

Ok, here's a scenario I have seen implemented before when dealing with HSMs and root CAs for a fairly serious PKI. You set up a 3 out of 5 share with each of the 5 keys stored on separate hardware tokens. The tokens are physically secured in safes, in tamper evident bags. To perform operations on the HSM, three out of the 5 tokens are required. The key custodians belong to different teams who can only open the safe for their token.

Now, you need to compromise at least 3 safes to do anything on the HSM. If a token is lost, stolen or damaged, there are still 2 others which can be used. Loss or theft of any two tokens does not compromise the HSM. Any unauthorised access to a token can be detected due to the tamper evident bag.

This gives you strong protection and assurance against any malicious insider or attacker. Having a single key (even if protected in a safe) is much weaker, and carries the risk of key loss (so you would have to have token backups, multiplying rather than dividing the risk).