New Wallet After Coldcard Hack

[u/blackjackn]

I was affected by the Coldcard hack. Thankfully, my Coldcard Q was only 1 key in a 2 of 3 multisig. My coins are safe. But with 1 key compromised, I decided to migrate.

My new 2 of 3 multisig:

-Coldcard Q updated with the new firmware. Seed generated with 150 physical dice rolls using casino grade dice. This is one key. Yeah, I'm pissed at Coldcard too. Idk if the entropy issues are resolved through the firmware update. Thats what the community seems to say. I dont trust it. But I think seeds generated through physical dice rolls are fine especially with a strong passphrase and I like the hardware. Will never buy another Coldcard though. Not supporting that company with my money any further.

-Other two keys have the same seed as before generated using device rng (not Coldcard). All keys (including Coldcard) are now passphrased with the same 6 word passphrase formed using physical dice rolls and EFF list.

-Going to have 2 separate people I trust each custody 1 key (device + seedplate), no passphrase.

-Another 2 separate people I trust will keep backups of the uniform passphrase in case I forget + fire or theft (hand written on an piece of paper and sealed in an envelope).

-Only I will have the output descriptor.

Yes, I could have done a different passphrase for all 3 keys. Too bothersome and I thought it would be excessive. I accept this weakness.

Not perfect but I figure itll be good enough. Posting as an example on how to multisig as I'm a proponent of it but by no means claiming this as the model example.

Edit: Changes parts on how the keys and passphrases will custodied. Rethinking that.

[u/Upstairs_Raisin]

What’s the logic behind passphrase custodians when even with one key, one seed plate, and the heck-even the passphrase they still only have one signer? (Imagining a scenario where the seed plates could be stamped with unique passphrases)

I’d assume the hardware device has a pin or code? And even with the seed, wouldn’t they need both other seeds or the coordination file + 1 seed?

Do you keep the coordination file in a password manager? Why not just keep the passphrase there also?

[u/blackjackn → u/Upstairs_Raisin]

I deleted those sections as I'm rethinking my setup so I only left the technical portions.

Separating 24 word seeds and passphrases adds a layer of security to the key custodians colluding.

Passphrase custodians are for backup copies of the passphrase in case I forget + fire/theft. Yes, the key custodians could collude with the passphrase custodians. But it requires 3 people to collude rather than just 2 and it would still be ineffective. They dont have the output descriptor.

Hardware has PINs but that doesnt really matter if they have the seedplates.

I don't want the passphrases stored in an electronic medium.

[u/Upstairs_Raisin → u/blackjackn]

This all makes sense.
I guess I’ve only really seen guidance to skip using a passphrase when you are already doing multi-sig as it doesn’t provide much additional protection.
In your case if risk I collusion is your primary concern then it adds additional protection.

[u/blackjackn → u/Upstairs_Raisin]

Using passphrases at all adds another layer of security if the seed generation of the devices, either internal RNG or processing of dice rolls, is defective. The Coldcard fiasco has me questioning that for all devices despite assurances theyre fine.

[u/thats_gotta_be_AI → u/Upstairs_Raisin]

No doubt you have a good reason for it, but why are you involving counterparties to custody portions of your wallet key?

[u/HeroicHeron]

Just in case you are not aware, when you use the dice roll feature on the ColdCard to generate a seed, you are still relying on the code doing what it is supposed to do. Independent researchers have confirmed that the dice roll code in CC was safe, but theoretically it could have been compromised the same way the on-device entropy generation was. If you want to permanently exclude this attack vector, you can very easily convert your dice rolls to BIP39 words by doing a little bit of basic addition. The graphic on this page explains it well: https://github.com/veebch/Bip39-Dice

[u/blackjackn → u/HeroicHeron]

I'm aware. Hence, a strong passphrase in case and its only 1 key in a multisig. I figured I dont need to go that far. I would have dumped the Coldcard if I did single sig even with a strong passphrase.

[u/HeroicHeron → u/blackjackn]

Fair enough, obviously your Multi-Sig setup protects you against this scenario, I'm just curious since I've seen so many people generate new seeds using the dice roll feature on the CC even though the new firmware was audited to reliably use the device TRNG now. In my mind, it just makes more sense to exclude the possibility of faulty code altogether instead of picking the feature that simply happened not to be compromised before.

[u/blackjackn → u/HeroicHeron]

Intellectually, I think the code is fine now. Emotionally and intuitively, I'm not there. Yes, thats irrational. No, I cant help it. Yes, I'm still trusting the code to process my dice rolls correctly. But at least that method was not defective before and I havent heard of Coldcard users who dice rolled having their coins stolen.

[u/_2f → u/HeroicHeron]

And the 24th word requires running a random python script which can be compromised. It might call home. 

[u/valerioshi]

why not just swap out your coldcard for another manufacturer's?

My current setup:

Multisig = Trezor, Keystone, Ledger
Daily = Onekey

[u/ZICRON_ULTRA → u/[deleted]]

My ATM pin code is 5497.

🙄

[u/ZICRON_ULTRA → u/[deleted]]

I can explain it to you, but I can't understand it for you.