What's the use of this md5() function?!

Bijan

Hi, I really can not understand what's wrong with storing plain text passwords in mysql! I mean we only use md5, encrypt or other functions to encrypt our password, right? So, why? If my password is "apple", then I can write it the way it is in mysql password field, or I just md5 it and then put it in there. So for the latter, I have to md5 all the entered passwords in the future and check if they are in the password field. Are we only doing this because if the phpMyAdmin password (mysql pass) was hijacked, nobody finds about the real passwords? What's the use of it really?

trooper

MD5 is a one way encryption method

What you are asking is essence is why encrypt data.

Well its good practice and whilst you may think that it may be safe in your MySQL db what happens if someone manages to get in and see all the user details

If the password is in plain text then the hacker could then "imperosnate" a valid user by logging in with their password - if its in MD5 format then its a lot more difficult

Incidentally you should add a a secret word (often called a "salt") to the password

So like this

$pwd = "secret"
$salt = "myspecialstring"
$realpwd = md5($pwd.$salt);

This improves the security even more - cuz if the hacker knew you were using md5 then they could calculate the pwd, but with the "salt" being added as well then this would make is a lot lot harder to try and crack


HTH

GM

superwormy

As stated above, md5() makes sure that if your database is compromised, they still don't have access to the actual passwords.

Further, md5() can serve to make sure you don't get dangerous sysadmins... if you were a sysadmin, and you had access to 500,000 plain-text passwords, how big a temptation ( and how easy to get at ) would those 500,000 plain-text passwords be for you?

Further, what if you work on a team of people, all of which program your PHP application. Do you trust EVERYONE you work with to not use those passwords ever? Think all of them will avoid the temptation to login to someone's account? Steal someone's account?

Weedpacket

Originally posted by trooper

This improves the security even more - cuz if the hacker knew you were using md5 then they could calculate the pwd,

Then it's not "one-way", is it? What you mean is that they could keep guessing possible passwords until they either got fed up or found a match - but that's a long way from "calculating" it. The salt does protect against this, but then so does using sensible passwords in the first place. However, most people are hopeless at coming up with sensible passwords, and I can't recall how many times I haven't been able to choose a sensible password because the software taking it was thick.

The official use of MD5 (that is, the one its inventor intended) is given in the official MD5 reference, RFC1321:

The algorithm takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input. It is conjectured that it is computationally infeasible to produce two messages having the same message digest, or to produce any message having a given prespecified target message digest. The MD5 algorithm is intended for digital signature applications, where a large file must be "compressed" in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA.

trooper

Weedpacket - the reaso i said "one way" is due to the fact that there is no "reversal" method (unlike say MCRYPT_ENCRYPT)

Weedpacket

I never intimated otherwise.

Bijan

Thanks! Now I can understand why I should use that md5() thing! I was thinking before that if I get access to someone's db, then I can easily create an account for myself and put the correct password ( md5(my_own_password) ) in there, I never thought of human's temptation toward sins and deception! Well, maybe I'm just too innocent! But that salt was cool too, if they even get the real password, then have no access to my php script. Thanks for your help, now I know why I should use it.