In a previous class, we learned a bit about one of the security measures Nintendo took to try to make sure content was authorized. We also learned a bit about piracy even in retro consoles with Nintendo's Disk System.

These have long been concerns, and likely longer than you realize. Majority of digital media tries to combat this somehow. There's tons of different areas we could look at for this, however, for now we'll keep our focus on games.

Sometimes the algorithms are later leaked or broken, sometimes they aren't. Whether or not the algorithm is solved is only partly due to the difficulty of the algorithm. It's also partially due to the level of interest. 

A CD key for the Street Fighter could have a lot if interest, and even if difficult to break still may be discovered just due to the number of hackers trying. On the other hand, maybe a movie releases with a video game adaptation. Even if the algorithm isn't complex and could be solved pretty easily, if the movie performs poorly and no one is interested in the game, there may not be anyone trying to break the product key.

We can look at Windows 95 as an example of an algorithm. This is a pretty simple on, be aware that most are more complex. On the The Windows 95 product keys are in the form XXX-XXXXXXX. 

To determine whether the key is valid, Windows 95 performs the following checks:

      The first 3 characters must not be equal to 333, 444, 555, 666, 777, 888 or 999.

      The last 7 characters must all be numbers from 0-8.

      The sum of the last 7 numbers must be divisible by 7 with no remainder.

      The fourth character is unchecked.

If all checks pass, the product key is valid. 

1. What is DRM?

2. Which DRM method did you find most interesting? 

3. Explain why.

4. If your publisher decided that you had to include DRM to reduce piracy, what type of DRM would you consider for your game idea?