Salting Passwords

The simplest way to store a password in a database is as a plain string

insert into users set email="kae@kvsites.ie", password="password";
["kae@kvsites.ie", "password"]

But, if someone hacks into the server, or you have a malicious admin, then those passwords can be stolen. This is a big security risk as passwords tend to be re-used by people for other purposes, such as PayPal, etc.

So, the next stage is to encrypt the password using a hash such as MD5:

insert into users set email="kae@kvsites.ie", password=md5("password");
["kae@kvsites.ie", "5f4dcc3b5aa765d61d8327deb882cf99"]

That /looks/ secure, but there are huge databases on the Internet with MD5 translations of all words, so it is trivial to hack these.
https://www.google.ie/search?q=5f4dcc3b5aa765d61d8327deb882cf99

The next stage is to “salt” the password by adding a prefix to it before hashing. For example, let’s use “123ghjzxc” as the salt key.

insert into users set email="kae@kvsites.ie", password=md5(concat("123ghjzxc", "password"));
["kae@kvsites.ie", "9f400bac0b5a9b3d66c9c98aae09fab5"]

This is much more secure now. A search for the MD5 hash will not return any results at all (well, this page… but you know what I mean).
https://www.google.ie/search?q=9f400bac0b5a9b3d66c9c98aae09fab5

Another method is to hash the password before prefixing it with the salt, then hashing again. This may be a bit more secure again.

insert into users set email="kae@kvsites.ie", password=md5(concat("123ghjzxc", md5("password")));
["kae@kvsites.ie", "d1dddda63a6dde54fb1740dffe3faa27"];

As an extra step, do all the MD5ing outside the database, so the password is not sent over the wire to the database.

Leave a Reply

%d bloggers like this: