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[-] Downcount@lemmy.world 14 points 1 year ago

Yeah, you actually better not save the users passwords in plain text or in an encrypted way it could be decrypted. You rather save a (salted) hashed string of the password. When a user logs in you compare the hashed value of the password the user typed in against the hashed value in your database.

What is hashed? Think of it like a crossfoot of a number:

Let's say you have a number 69: It's crossfoot is (6+9) 15. But if someone steals this crossfoot they can't know the original number it's coming from. It could be 78 or 87.

[-] twolate@discuss.tchncs.de 8 points 1 year ago

Dumb question: isn't it irrelevant for the malicous party if it's 78 or 87 per your example, because the login only checks the hash anyway? Won't both numbers succesfully login?

[-] Downcount@lemmy.world 5 points 1 year ago* (last edited 1 year ago)

Additional to what others have said: The "salted" part is very relevant for storing.

There aren't soooo many different hashing algorithms people use. So, let's simplify the hashing again with the crossfoot example.

Let's say, 60% of websites use this one algorithm (crossfoot) for storing your password, and someone steals the password "hashes" (and the login / email). I could ran a program that creates me a list of all possible crossfoots for all numbers for 1 to 100000.

This would give me an easy lookup table for finding the "real" number behind those hashes. (Those tables exists. Look up "rainbow tables")

Buuuut what if I use a little bit of salt (and pepper pepper pepper) before doing my hashing / crossfooting?

Let's use the pw "69" again and use a salt with a random number "420" and add them all together:

6 + 9 + 420 = 435

This hash wouldn't be in my previous mentioned lookup table. Use different salts for every user and at least the lookup problem isn't such a big problem anymore.

[-] Woe2TheRepublic@lemmy.world 4 points 1 year ago

This was super helpful ๐Ÿ™๐Ÿผ sent me down a whole other rabbit hole of learning

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this post was submitted on 17 Jul 2023
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