I asked a question yesterday about password safety...

I am new at security...

I am using a mysql db, and need to store users passwords there. I have been told in answers that hashing and THEN saving the HASHED value of the password is the correct way of doing this.

So basically I want to verify with you guys this is correct now.

It is a classifieds website, and for each classified the user puts, he has to enter a password so that he/she can remove the classified using that password later on (when product is sold for example).

In a file called "put_ad.php" I use the $_POST method to fetch the pass from a form. Then I hash it and put it into a mysql table. Then whenever the users wants to delete the ad, I check the entered password by hashing it and comparing the hashed value of the entered passw against the hashed value in the mysql db, right?

BUT, what if I as an admin want to delete a classified, is there a method to "Unhash" the password easily?

sha1 is used currently btw.

some code is very much appreciated.

Thanks