What is CSS (in DVD Copy Protection)?

What is CSS in DVD & Why Employ CSS to DVD Production?

CSS (Content Scrambling System) is a DVD copy protection technology employed on almost all commercially produced DVD-Video discs. It is used on DVDs to encrypt the data so that only licensed DVD players can decode it then play the DVD content smoothly.

You may be not familiar with this copy protection term, but you may have experienced the troubles it brought: Most of the time when you want to backup a commercial DVD to computer, or re-burn to DVD discs to share with friends, you failed even though you are the owner of the DVD.

To make it clear why employ CSS in DVD, we need to firstly take a look at how does DVD store video/audio content and how do people copy DVD.

DVD video is stored as MPEG-2 format which is easily portable to a personal computer (as a .mpg or sometimes .vob file) where it can be viewed. So it can also be easily copied. Originally, CSS is employed by content owners (like DVD movie producers) to prevent illegal copying and distribution of digital media such as video and audio. Once added CSS copy protection to a DVD, it will prevent byte-for-byte copies of an MPEG (digital video) stream from being playable. Besides, it provides a reason for manufacturers to make their devices compliant with an industry-controlled standard.

CSS Keys

There are three sets of keys associated with the system:

1. Disc Key: Used for decrypting a title key on a DVD;
2. Title Key: Used for scrambling and descrambling DVD data known collectively as a title, which could be a complete motion picture, a trailer, or some similar self-contained unit;
3. Player Key: Used for decrypting a disc key on a DVD; each DVD player manufacturer is allocated one of approximately 400 player keys to incorporate in its players.

The Problem with CSS

It is that the underlying cryptosystem and keys need to remain secret. Even modern cryptosystems are completely open and their workings can be known by anyone. CSS also has a very small number of keys (around 400 only) - another weakness in any cryptosystem. With so many DVD player manufacturers and millions of DVD users, something is bound to go wrong; secrets will leak or someone will crack the system.

How to Remove CSS when Copying DVD?

To copy DVD which is protected with CSS, you need to remove the DVD copy protection with DVD ripper software, like WinX DVD Ripper Platinum. It is the No.1 fast DVD ripper that supports decrypting CSS DVD copy protection and copying DVD movie on your computer. What's more, with this DVD ripper, you are also enabled to copy DVD to play on iPhone, iPad, iPod touch, Android phones/tablets, WP8, PSP, and so on.

Guide to remove CSS and other Copy Protection Techs from DVD