Christopher Allen

@ChristopherA

#SmartCustody Adversary — Denial of Access

DENIAL OF ACCESS is a very pragmatic adversary that can affect your cryptocurrency. What if you physically couldn't get to the location where you stored the private keys that protect those assets? (1/9)

6/4/2020, 6:12:55 AM

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Christopher Allen

@ChristopherA

I had to imagine some less likely scenarios when I first wrote about this adversary, like storing keys in a corporate safe before the company went out of business, or with a friend who died. (2/9)

6/4/2020, 6:12:56 AM

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Christopher Allen

@ChristopherA

But we've seen a more likely situation in recent months: COVID-19 lockdowns. Banks have been accessible, but what if you left private keys with friends or family? It would have been illegal to retrieve them. What if they were at a work place and you couldn't go there? (3/9)

6/4/2020, 6:12:57 AM

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Christopher Allen

@ChristopherA

The recent riots offer another very real example of a physical DENIAL OF ACCESS. There might have been curfews blocking your access, or it might be unsafe to go and retrieve your cold storage keys. (4/9)

6/4/2020, 6:12:57 AM

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Christopher Allen

@ChristopherA

We take our freedom of movement for granted in the first world, and that may well be the case when all of this is done. But our #SmartCustody book anthropomorphizes adversaries so that you can better understand them and better consider the concretely. (5/9)

6/4/2020, 6:12:57 AM

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Christopher Allen

@ChristopherA

Think about where you store the secrets that protect your cryptocurrency and other digital assets. Is there any way you could lose access to that? (6/9)

6/4/2020, 6:12:58 AM

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Christopher Allen

@ChristopherA

There are of course other forms of DENIAL OF ACCESS. What if your hardware or processor manufacturer bricks or freezes all of your secure devices? Estonia did this is 2017 due to an security flaw, preventing access to all e-ID services. https://amp.insider.com/estonia-freeze-e-residency-id-cards-id-theft-2017-11 (7/9)

6/4/2020, 6:12:58 AM

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Christopher Allen

@ChristopherA

One of our top solutions is redundant storage. If you have keys in more than one place, particularly disparate sorts of places, then it's less likely that you'll lose access to all of them. Obviously, any solution may introduce its own adversaries as well. (8/9)

6/4/2020, 6:12:59 AM

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