What's the safest encryption I can use for a user to login to my program? - md5

Question

I'm writing a program and before it loads I want the user to enter the correct password without storing the password anywhere in my code. I've implemented MD5 hashes before but from what I've read they're outdated and can be broken. There are a few sites out there that attempt to reverse engineer and MD5 hash. What's the strongest encryption I can use to keep prying eyes out of my program (e.g., The NSA)?

Answer 1

"Encryption" is not the right thing to do for storing user passwords - as by design an encrypted password can be decrypted. As you said - hashing is the way to go.
MD5 is outdated, and I believe the current recommendation is sha1.
Note that there are ways to reverse any hashing algorithm to acceptable input. The commonly accepted standard to make this much more dificult is to add a unique "salt" to all passwords before putting them through the hashing function. A common mistake made when adding salts to passwords is to use the same salt value on every password in the database.
When salting passwords, use a unique value, for example the user ID, or the created date/time string for the user record. This will prevent attacks based on rainbow tables because there will be no existing ready to use rainbow table for your stored password hashes.
I personally like the approach of using the created date / time string of the user as it's a value that should never change and will be available and will likely be different for each user the the database.
Eexamples below assume you are familiar with PHP - however the concepts can be applied to any language.
Example:
Before saving a new user into the database:
$date = date('Y-m-d H:i:s');
// save this same value into the user record somewhere
$passwordHash = sha1($user['created_date'].$_POST['password']);
// and save the $passwordHash value into the password field for that user
To authenticate a login attempt, use something like the following:
function authenticateUserLogin($email, $password) {
$user = $db->fetchRow('SELECT * FROM users WHERE email=?', array($email));
if (!$user) return false;
$passwordHash = sha1($user['created_date'].$password);
return $user['password_hash'] !== $passwordHash;
}
To update an existing users password, use something like...
$passwordHash = sha1($user['date_created'].$newPassword);
$db->query('UPDATE users set password_hash=? WHERE id = ?', array($passwordHash, $user['id']));