It's a SHA-1, per https://github.com/home-assistant/supervisor/blob/main/super....

Their docs link to this explanation, in which the link I give uses an example that appears to be identical to the HA implementation - https://blog.cloudflare.com/validating-leaked-passwords-with...

I might be misunderstanding, but if the first 5 digits is a unique hash in the HIBP database then an attacker can replay that request, then lookup the hash. But "When hashes are grouped together by a Hash Prefix of 5 characters, we find the median number of hashes associated with a Hash Prefix is 305." {ibid}.

If you've acquired leaked passwords as HIBP have, you then just make hash lookup tables, then you have 305 potential passwords to try, or try and whittle down. If the bucket of hashes has "hunter2" in it, for example, then that's perhaps a good one to try - https://blog.cloudflare.com/validating-leaked-passwords-with... is worth reading.

because why should my electric light scheduler be in the business of inspecting my passwords and furthermore involving third parties in inspecting my passwords?

It's probably overzealous of HA to do this, but ultimately it isn't. The context missing from this HN thread so far is that the reporter, Viss, has been frankly not credible on security in general for a really long time, despite being a big name in the community on stuff like OSINT. A lot of people in the OSINT sphere basically believe any information being public at all is a security risk and prefer you to pay them exorbitant consulting fees to come up with numerous ways of rephrasing their circular reasoning about why.

I think the main issue is that you don't expect a service to send anything related to your data without letting you know. Even if it's a ping "alive" sent to a server they own.

Imagine if your smart toilet would just send a small anonymized message to a urine sampling analysis service so it can let you you know your cholesterol levels are a bit high, totally anonymous, totally for your benefit. Maybe it's a great feature, but would anyone expect this to happen without consent / opt in?

It's a "severe invasion of privacy" to send anything to the Internet without the user's permission, period. Privacy is about having control over what information you disclose, how much, and to whom. Developers shouldn't be allowed to make that decision on behalf of the users.