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arcfour | on: Horible public key tricks
>Nobody checks your private keys

You're implying that they should???

taspeotis | parent
I suspect private keys should receive a nominal check, that they can't be guessed by smashing the number 4 on a numpad.
arcfour | root | parent
So we either expose the key material for inspection (very obviously bad) or we try and brute force how many possible "weak" private keys from the public key to see if they check out?

Note that this is on the order of trillions of useless computations at least per year since almost everyone just uses a CSPRNG or HWRNG available in all modern computers to generate their keys sanely.

Now, for CAs, sure because that is a very small number of certificates. But that's a completely different discussion and also however eMudhra managed to lop off all of the entropy except for the final byte was wildly incompetent and not something a layman would even consider doing.

It's also not the job of the CA to detect you being an idiot. You can go post your private key online after getting your certificate if you so wish, the CA may revoke it if they find out but they're just in the business of helping you secure your communications with others. If you wish for them to actually be insecure... You are silly, but that was always allowed.

hxtk | root | parent | next
FWIW, at at least some of the ACME CAs still willing to sign RSA certificates will make a cursory attempt at brute forcing your private key to make sure you don’t have one very tiny prime and one big one. Tom7 encountered this when he tried to implement the least secure website he could without being flagged by the browser. He ended up using a public modulus with four prime factors instead of 2.
alwa | root | parent | next
The “4” affair did make me wonder… as a non-expert, I’d always kind of assumed that—with all the ceremony around key ceremonies and all—there might be some way to provably assert the set of techniques used to arrive at the key in the first place. XYZ hardware-signed source of entropy was sampled at DEF time and input into ABC signed chunk of algorithm to arrive at the private key…

In fact I assumed that’s why somebody might explicitly choose “4” as their key: to make it as easily detected as “TK” in a copy edit, or a prefix-designated API key in a repo, or an “@example.com” that slides by into a serious environment.

We really go on a pinky swear across the public CA ecosystem?

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taspeotis | root | parent
I am not sure how trillions of computations will occur, simply attempting 0-255 would have found ... all? ... of the eMudhra fuckups. Maybe a few million instructions burnt on a CPU.
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