myAltCaptcha: CAPTCHA validation using hidden form fields

This class is an alternative to the standard CAPTCHA utilities. Your users don't have to enter text that they can hardly read. This class performs the standard CAPTCHA validation to distinguish robots from humans by using hidden fields as honeypots. Field names are hashed so bots don't know which fields require human entry.

The class checks whether the form is submitted too fast or too slow to have been submitted by a human user. It also checks whether the values stored in the hidden inputs are valid.