Trying to create a cryptographically secure way to hash a user's password so that I can find out if the new user is different from the original password without having to save the original password text. Is this something doable?
You have a user who enters their old password along with the new one (which you should do anyway). Compare the hash of the old with the stored hash of the old for verification, then compare the two open passwords: old and new.
No, it’s not that whole idea with hashing!
You will need to use reversible encryption.
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