Downloading copyrighted PS3 games you don’t already own is piracy and violates copyright laws in most countries. However, if you own a legal copy of the game, you can dump your own PKG and RAP files from your console.

Here is the standard workflow for manually installing a PS3 game from PKG and RAP files.

Here’s the solid, factual breakdown:

It is worth noting that not all PS3 games are distributed as PKG files. Disc-based backups are often saved as files. These do not require installation in the same way. You simply copy the ISO to the /PS3ISO/ folder on your internal or external hard

Here is where the "crack" comes in. RAP files are licenses. When you buy a game from the PlayStation Store, the PS3 downloads a RAP file (or an encrypted RIF file) that proves you own the license.