[eXpl0it3r]

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.

[godelski]

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

[sharperguy]

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.

[account42]

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?