I'm trying to obfuscate the URLs to the pages where content is displayed. Content pages are displayed by getting the content id number as a GET variable in the URL. I want to obfuscate the URL (as is described by this SO post). I tried the methods in both answers but one method gave overly long codes, and the other gave overly predictable codes.
I'm working in PHP, and I'm using a MySQL table to store content; the content id is an automatically incrementing column. This means that if I didn't obfuscate my URLs users would be able to see in the URL exactly how many posts there are on the website, and could change the URL to see different posts. I want to avoid this.
I was hoping to have obfuscation similar to Imgur.com: their content ID codes are each a 5-character code containing letters, capital letters and lowercase letters.