What is SALT and how do i use it?

Question

I have been searching around and I am still unsure of what a \"salt\" is and how to use/implement it. Sorry for the noobish question, I am self learning php.

Answer 1

Let us spice up things a little by combining several algorithms for hashing, making a double hashing algorithm:

$password = "myPassword";
$salt = sha1(md5($password)).'k32duem01vZsQ2lB8g0s'; 
$password = md5($password.$salt);

As you can see, we first hashed the password using double hashing algorithm (md5 and sha1) and concatenating with a key created salt value. After that, we combined real password with generated salt value and hashed it again with md5. The advantage is that this way alt value is random and it changes, making it nearly impossible to break. I mean, if you can wait for a million years and have a super computer on your hands, try to break it.