In this new tutorial on DevShed, they walk you through the creation of a secure login script that uses sha256 encryption, a captcha to prevent automated signups, XSS attack protection and several other features.

Recent advancements in PHP offer the developer a variety of tools to improve the security of login systems. [...] This programming tutorial will teach you how to create a simple, yet secure login script utilizing PHP using MySQL and bracing for XSS attack prevention.

Other features include no persistent logins, preventing direct file access, an idle timeout on the user session, protection against session fixation and anti-brute force measures. Full (procedural) code is provided as well as screenshots from phpMyAdmin showing the database table structure. You can grab the code for the project here.