How is something digitally unduplicatable?

Question

Not a programmer and don’t have much knowledge of code but…

In the physical world though there are ways of duplicating things, i.e moulds in a factory, but most things are unique and not easily duplicatable.

In the digital world, I would presume it’s the opposite, most things are easily ‘duplicatable’ because you can just copy and paste code.

How are things in the digital world made ‘unduplicatble?’

Is it just a case of hiding the code? Therefore it is just difficult to duplicate not impossible.

In: Technology

Answer 1

It revolves around:

– encrypting things (e.g. data on a dvd, Blu-ray)

– preventing people from running their own code, or from accessing the code that is running (many phones, dvd players, TVs, etc.)

– obfuscation, if the first two are not possible (games and paid software on a pc)

Let’s take an example of movies/dvds. The movie data on each dvd is encrypted. Companies selling dvd players can request a key to decrypt the content, but for that they must guarantee that the dvd players they sell will respect content lock, and not let users copy copyrighted content (so, the player can copy the content, but doesn’t let you do it).

Note that if the key is compromised, then anyone can read and copy the disks, which is essentially the case for DVDs.

Then, the dvd players forward the video content through the HDMI port. Same thing applies here, the content in the HDMI cable is also encrypted. Your TV has a decryption key, but doesn’t let you access the decrypted data.

On phones, usually there is a hardware chip that checks that the code that is running has been signed by a predetermined key (that only the constructor runs). As a result, only the software validated by the constructor can run on the device, and this software respects content protection restrictions.

Sometimes it’s not possible. For example, on a PC the user can run whatever code they want (not entirely true: each piece of hardware, CPU, GPU, etc, run their own code in the chip, the “firmware”, which is not always user accessible). In this situation, since the user can see everything, you cannot theoretically prevent him from accessing the data. But you can make its access very convoluted, so that a user will not understand how to find the data, even though it’s technically there.