COLDCARD RNG incident the public record, collected and explained
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r/Bitcoin: about the recent Coldcard attack

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https://www.reddit.com/r/Bitcoin/comments/1vbnvzn/about_the_recent_coldcard_attack/

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    post: 1vbnvzn
author: Prestigious_Ear_8055
created_utc: 1785496125
title: About the recent coldcard attack
body:
I’m trying to understand the security vulnerability of any cold hardware device.

Since the attacks targeted coldcards specifically, it means the RNG of coldcard seed generations got figured out and they were able to brute force the secret phrase.

Meaning the secret phrase generated by coldcards were predicted and narrowed down, the possibilities were NOT astronomical (they never were to begin with technically?)

However, this does not mean any secret phrase can be brute forced

Even cold devices with weak 12 words generation for example, cannot be targeted randomly by brute force since the possibilities are still enormous, UNLESS THE RNG of the device used to generate the secret phrase gets figured out and possibilities get narrowed down.

So each cold device has its own entropy, meaning for 12 astronomical possibilities of words to get figured out exactly as they are would require software breach of the cold device

Is this analogy true?

Even if you don’t use passphrase, secret phrases in general are not at risk unless their main RNG gets figured out.

But does this mean no cold device is truly random?

Also if someone downloads a cold wallet from a trusted source, runs it on an old laptop.  
The seeds generated will not ever be brute forced unless the laptop’s antropy gets figured out (time etc) ?

One final question and it gets a bit complicated.  
Is using a random old device, like a laptop, to generate seed phrases (offline airgapped of course) safer than using a globally known cold wallet brand?

Meaning figuring out a random laptop’s time and ram usage when seeds were created is near impossible if a hacker doesn’t know you have a cold device on that laptop model specifically, unless he gets his hands on it or has to emulate it (but won’t know settings you haed?) compared to having a publicly known cold wallet brand which many people use with one software entropy?

comment: p0upe8p
parent: t3_1vbnvzn
author: frugaleringenieur
created_utc: 1785496308
edited: false
body:
To your assessment how the ColdCar incident played out - yes, quite accurate.

Regarding your other questions: the best creation of entropy is always without a computational electronic device. Creating a good random number generator is hard on its own. Having a minor bug can have catastrophic consequences on top.

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