Christopher Allen

@ChristopherA

#SmartCustody Adversary - Key Fragility

KEY FRAGILITY. For many, this is the big adversary in digital-asset management: the one most likely to cost you your assets. That makes it a big concern in #SmartCustody too. (1/13)

7/7/2020, 3:04:00 PM

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Christopher Allen

@ChristopherA

To offer the motivation: "I am entropy writ small. All I need to do is mislay a digit or two from a ridiculously large number, and my job is done." (2/13)

7/7/2020, 3:04:00 PM

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Christopher Allen

@ChristopherA

But it's an adversary that you can actively help: "Perhaps you could make my job easier by encoding or obscuring your key or by maintaining just a single copy; complexity and singularity both beget fragility in different ways.." (3/13)

7/7/2020, 3:04:00 PM

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Christopher Allen

@ChristopherA

In other words, KEY FRAGILITY is the problem of not just losing your key, but copying it wrong or having it corrupted in storage or even losing it due to the difficulty of a scheme for splitting it up. A private key is complex and that makes it a point of failure. (4/13)

7/7/2020, 3:04:00 PM

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Christopher Allen

@ChristopherA

The tales of losing keys to cryptocurrency are legion. A bug in the code wrote the the wrong key to disk. Keys on a hard drive accidentally erased, a hard drive sent to the dump by a maid. Paper keys lost in a fire, others turned to mush by a fire fighter's hose. (5/13)

7/7/2020, 3:04:01 PM

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Christopher Allen

@ChristopherA

You can even lose a key by losing the PIN to your hardware wallet, a number that you probably thought was very simple to recall. (6/12) https://www.wired.com/story/i-forgot-my-pin-an-epic-tale-of-losing-dollar30000-in-bitcoin/

7/7/2020, 3:04:01 PM

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Christopher Allen

@ChristopherA

So don't place trust in mnemonics. Don’t assume that you can remember that extra BIP38 secret word. Definitely don't assume you can put your key in a memorized brainwallet! (7/13)

7/7/2020, 3:04:01 PM

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Christopher Allen

@ChristopherA

Instead, have faith in manufactured titanium. You can etch your key into it, and as long as you make sure it's clear and precise, and that it's stored safely, it'll be there, forever (or close enough for your purposes). (8/13)

7/7/2020, 3:04:01 PM

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Christopher Allen

@ChristopherA

This adversary also suggests that you don't want to out-clever yourself. Every single thing you do to make a key harder to access, from hiding it to encrypting it makes it that much more likely that you'll lose it. (9/13)

7/7/2020, 3:04:01 PM

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Christopher Allen

@ChristopherA

Among my colleagues that contributed to bitcoin-core, an informal survey showed the greatest losses were due to KEY FRAGILITY, in particular loss or misuse of an added BIP38 secret word. (10/13)

7/7/2020, 3:04:02 PM

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Christopher Allen

@ChristopherA

We focus on single key cold storage scenarios in v1 of #SmartCustody, future multisig scenarios can address some risks, multisig also means that more information needs to be backed up, and successfully restored. So KEY FRAGILITY will continue to need to be addressed. (11/13)

7/7/2020, 3:04:02 PM

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