Greetings,
I can do it for you.
There's three essentials steps that we care about when developing a user access mechanism:
1) Security. We apply methods that encrypts passwords and all sensitive data. Today, most web app's lacks of security and eventually, they get hacked.
2) Coding. All system rules are specified and developed. We keep contact all way long this step, so everything will do the exactly thing you want to.
3) Delivering. All the code will be strict well documented, so you can track every business logic solution.
Every time a step is concluded, I'll contact you, so we can keep things within the scope you ordered.
I hope we can work together.