So i know you are going to say this is bad, but i really dont like using a database as it is confusing and hard at the same time. I also think storing usernames and passwords in a file is bad, but both the username and password would be encrypted using md5. I dont think this is secure enough though though because im going to make it public. If you could give me tips on how to make this better please tell me.
Also You will only have two attempts per minute ;) Here is my idea: https://drive.google.com/file/d/0B19YDO3uT0ClaVZsYjRFRVZkUzA/view?usp=sharing
Also if you could give me examples on how and where to store the file in the webserver? i am not very good with php to be honest