Book Image

PHP 7 Programming Cookbook

By : Doug Bierer
Book Image

PHP 7 Programming Cookbook

By: Doug Bierer

Overview of this book

PHP 7 comes with a myriad of new features and great tools to optimize your code and make your code perform faster than in previous versions. Most importantly, it allows you to maintain high traffic on your websites with low-cost hardware and servers through a multithreading web server. This book demonstrates intermediate to advanced PHP techniques with a focus on PHP 7. Each recipe is designed to solve practical, real-world problems faced by PHP developers like yourself every day. We also cover new ways of writing PHP code made possible only in version 7. In addition, we discuss backward-compatibility breaks and give you plenty of guidance on when and where PHP 5 code needs to be changed to produce the correct results when running under PHP 7. This book also incorporates the latest PHP 7.x features. By the end of the book, you will be equipped with the tools and skills required to deliver efficient applications for your websites and enterprises.
Table of Contents (22 chapters)
PHP 7 Programming Cookbook
Credits
Foreword
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Safeguarding forms with a CAPTCHA


CAPTCHA is actually an acronym for Completely Automated Public Turing Test to Tell Computers and Humans Apart. The technique is similar to the one presented in the preceding recipe, Securing forms with a token. The difference is that instead of storing the token in a hidden form input field, the token is rendered into a graphic that is difficult for an automated attack system to decipher. Also, the intent of a CAPTCHA is slightly different from a form token: it is designed to confirm that the web visitor is a human being, and not an automated system.

How to do it...

  1. There are several approaches to CAPTCHA: presenting a question based on knowledge only a human would possess, text tricks, and a graphics image that needs to be interpreted.

  2. The image approach presents web visitors with an image with heavily distorted letters and/or numbers. This approach can be complicated, however, in that it relies on the GD extension, which may not be available on all servers...