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Comment by Ra8 | Hacker News Reader

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Ra8

> Whenever I've written authentication, passwords are hashed on the client side and never transmitted in the clear.

Unless I'm misunderstanding what you're doing, this achieves nothing.

Hashing the password on the client side makes the hash the password, and MITM attacks are still possible.

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Sure, you could MITM still if all you do is that, as with anything it depends on what you are defending against.

If you are defending against clear text being discoverable, then bcrypt hashing with a unique salt on the client is good enough.

If you are trying to prevent MITM you can combine that salting with public/private key transmission of the bcrypt hash to the backend (effectively the same idea as pass keys without the downsides).

MITM just affects your service, and doesn't always matter depending on what the service is, for example, a recipe manager doesn't need to have bullet proof security.

What if the hash you're sending is discovered? I can use that to login to the service; it offers the same protection as a plain text password.

As the hash is being encrypted with the public key in the client, that would require that the client be compromised. In which case the original password is already exposed at that point, thus a discussion of the transport is no longer the concern.

The point of a hash is that the password is not stored on the machine long term. Thus, if an attacker gains access to the back-end and exports all the hashes, you can't reuse the hashes themselves to login. I.e. you need to do a password-cracking attack, which is infeasible with a password of sufficient length.

I don't care if someone gets my password hash. They aren't going to crack it due to the complexity of it.

Here is my hashed password. Good luck:

    $argon2id$v=19$m=65536,t=3,p=1$YTE4NzBkMDIwMjRhMGY5NzU4OTc2ZWY5YzI0N2RjOTY$GSBlUwWxr4BBs+5o5Ye2NphT9PFeWx4ECG6siED9uVQ

You can't use that to login to my system. You can only use it to validate if I give you my password...

Correct. The hash effectively is the password at that point.

If you’re storing the hash unencrypted in the DB, and it’s “just” a hash so why not, you’ve gone backwards.

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