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Is it fine if a website says "email already in use" before you hit submit? (lemmy.world)
submitted 1 year ago by to c/cybersecurity@sh.itjust.works
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I remember hearing before that it's a sign they are storing your info unencrypted but I never checked.

Is this true? I was logging into a .gov website and noticed it does that.

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[–] 1 point 1 year ago (2 children)

Not saying you're wrong, what you're saying makes sense, but my cryptology classes describes the stages of hashed authentication the way the guy you're replying to describes things (client sends hash of password, server compares hashes).

I'm not saying what I was taught (intro level cryptology) is correct, up to date, or into the technical weeds enough to distinguish, but can you provide a source that backs up your position?

I'm very interested in this discussion and I'd like to see an authoritative source. I can pull the book I am referencing if you'd like, let me know and I'll find it.

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  • [–] 2 points 1 year ago (1 child)

    I would be very interested in that book. My university did not provide explicit book sources, so I can't tell you what that is based on, but here are the relevant slides (from page 9). Server-side hashing is so ubiquitous as the standard that e.g. OWASP cheat sheet doesn't even explicitly say it, but their recommendations hint at it.

    A quick google search on the topic revealed others with the same opinion: stackoverflow stackoverflow. The second link (accepted answer in the same thread) argues that with a protocol around it, it can make sense, but never in the situation described here. There needs to be a meaningful computation on the server's side, otherwise the described scenario can happen.

    It's a bit difficult to find papers on that because server-side hashing is standard, but here, for example, is a paper that explores client-side hashing (see the introduction with a reference to server-side hashing and section 2): Client Password Hashing paper. Very interesting is also section 3.4. Similar paper: Client-side hashing for efficient typo-tolerant password checkers. Essentially, both suggest that to avoid the described attack, both server-side and client-side hashing is necessary (but the server-side hash can be weaker), see "Authentication attacks after leaks". Neither paper describes how the client-side hashing is done on the Chinese websites they mention.

    You'll also find that many frameworks (e.g. ASP.NET, Laravel) implement server-side hashing.

    My conclusion from the little research I did after your prompt is that client-side hashing can work, but it's dangerous if done incorrectly (e.g. when done as suggested above), due to the scenario I described.

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