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jimbocoin 🃏 10mo ago

As you know, I’m in favor of offline seed *generation*. However this is offline *computation*.

I advise against seed splitting using Shamir’s secret sharing or spinoffs like Codex32. CoinKite’s seed XOR also falls into this category. These schemes bring all the seed material together at the same place and time.

This is an unnecessary security risk. Anyone who gets the combined seed after reassembly can spend all coins in the wallet, forever.

Genuine multisig is a superior solution. With multisig, the keys don’t have to come together. You can get each signature at each location separately, eliminating the single point of failure. #Bitcoin nostr:note1m6x7lan27tntu9tzk4aj4njvgd0chja835de07save9pjr7wnxusywnwh2

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Discussion

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Orthodoxtr 10mo ago

Single points of failure are for fiat, not faith (in Bitcoin).

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Poetstry 10mo ago

Multisig: keys like stars, scattered but forming constellations of security. ✨

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Abstract Equilibrium 10mo ago

The "exists in multiple places at once" property of multisig signer quorums is underappreciated by the general public.

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Marc Kat 10mo ago

I like seed XOR and SSS for redundancy, but you make some valid points.

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Marc Kat 10mo ago

I also use multisig. I would never use seed XOR alone.

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jimbocoin 🃏 10mo ago

Using a passphrase (25th “word”) is comparable. You can use this technique along with multisig. It suffers from the same single-point-of-failure as shares, but the passphrase you store only in your head.

In this way, a passphrase is additive to your multisig security posture, compared to shares which weaken it.

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Marc Kat 10mo ago

I'm afraid that's too complex for my wife. Seed XOR is also too complex for her, but not me. I like Seed XOR because it does not add complexity for my wife because I can have the seed(for her) and split the seed(for me, the bitcoin autist🤓).

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Marc Kat 10mo ago

I am also shell shocked from the pandemic. I used to keep my key in a safe deposit box only, but 5 years ago, I couldn't access my Trezor for 3 months and when I finally did, I learned my passphrase had a typo. I figured it out after a couple weeks, but I don't like using passphrases with multisig because of this.

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Marc Kat 10mo ago

By the way, I'm not arguing with you to be a jerk, but to bounce off ideas and improve my own security.

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jimbocoin 🃏 10mo ago

It’s OK. There are two ways to lose your coins: you lose access to the keys, someone else gains access to the keys. Defending against either one in isolation is easy. Security is about balancing both.

Seed XOR is equivalent to a 2-of-2 multisig. IMO, genuine 2-of-2 multisig is superior, for the reason previously mentioned: that seed material can be kept separate at all times.

The tradeoff is that witness data on chain is marginally larger, making spends more expensive. Spends also reveal the fact that it was 2-of-2, so slightly less private (unless using Taproot, which would be the same as single sig privacy wise).