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Comment by nomilk | Hacker News Reader

> I found (it) not actionable

Tangental, but I found 'Have I Been Pwned' useless too because you can't enter your email and find leaked passwords associated with the address, instead you have to enter each password (and repeat for every password you want to check).

I know there's an explanation that the raw password is not being sent and instead being hashed locally and only part of the hash is sent. But I don't know how to verify that and it feels wild to type passwords into a random website. (if anyone knows how to verify HIBP does only what it says it does [rather than blindly trust and hope for the best], would love to read more about it)

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I always thought that it could be reasonably simple to have a safe alternative. Have people enter a SHA256 of their password instead, and match against a database of other hashes.

Almost everyone interested in checking for password leaks knows how to generate SHA256 of a string. And those who don't shouldn't put their passwords on the internet.

Or even better, generate hash for all passwords in the database, package these hashes together with a simple search script and let people download it. That way, you are not sending any information anywhere, and noone can exploit the passwords, because hash is a one way function.

Then again, that download could be really large. I admit I have no idea how much storage would that take. But it's just text, so easily compressible. And with some smart indexing, it should be possible to keep most compressed and only unpack a relatively small portion to find a complete match.

Then again, I have virtually no background in cryptography, could be something horribly wrong with this.

That's already what is happening...

When you do a check on https://haveibeenpwned.com/Passwords nothing is sent to the server. Instead the password is hashed locally and a list of the hash range is downloaded, which contains all the hashes and the number of occurrences.

The server doesn't receive the password, neither in plain-text nor hash form.

They meant you submit the checksum instead of your password. Replace "Password to check" with "Checksum to check"

It would be easy enough to add this as a "secret" feature:

* user submits password * gets hashed client side * server compares it against stored hashes * server also re-hashes the stored hash, and compares it against the hash received from the client

This would effectively mean that either entering the password, or the password hash would correctly match, since when entering the hash you are effectively "double" hashing the password which gets compared to the double hashed password on the server.

The upside is that users who don't understand hashing or don't feel like opening a sha256 tool wouldn't have to change their behavior or even be confused by a dialog explaining why they should hash the input, while advanced users could find out about the feature via another channel (e.g. hackernews).

The downside would be that it adds an extra hash step to every comparison on the sever. It's hard to know how expensive this would be for them.

Care to explain how you can tell what scripts gp was sent for the page https://haveibeenpwned.com/Passwords and what scripts he will be sent on future visits?

Well of course a hostile actor could use this incredibly accessible resource to test a bunch of emails and find their passwords.

Though perhaps there could be a service where you enter in an email address and it sends an email to that address containing the passwords. That would be a slightly more complicated server to set up though

OK, I would pay for this service.

It doesn't use any information that's not already exposed.

It reveals the extent of my problem to me.

Im 99% sure this is exactly what HIBY used to do, and changed their processes. I'm unsure if this was due to government pressures or what

> (if anyone knows how to verify HIBP does only what it says it does [rather than blindly trust and hope for the best], would love to read more about it)

I recall HIBP documents their hashing protocol so that it should be possible to have a non-web client you can trust more.

https://haveibeenpwned.com/API/v3#PwnedPasswords

There's an API[0] that takes a prefix of a hash.

I don't know how to verify what the website does, but I think that in a few minutes I'll be able to put together a CURL call that does what we're hoping the website does.

[0]https://haveibeenpwned.com/API/v3#PwnedPasswords

Bitwarden's web vaults has a reports feature which allows you to check this in bulk.

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