So, I downloaded my first Virtual Console game the other day and immediately backed it up to an SD card. The process worked flawlessly but it took a little while for the Wii to save the game. I thought at first it had crashed because the actual game data wasn’t particularly large (about 1 MB for the raw ROM data). After popping the card into a reader for my Mac, it turns out the code/data for the game had grown on the SD card to about 5 MBs. That’s quite an increase and I began to wonder why it had grown in size by a factor of five. There are quite a few opinions as to what constitutes the increase in size on the Internet, and the possible reasons I give you here are no different, but I tried to sift through the possibilities and come up with the three most likely reasons:

• It’s very likely the Wii uses a symmetric encryption algorithm to protect the data, since asymmetric encryption wouldn’t really add to the security of the system in an environment where both the private and public keys would need to be stored locally in system memory. If they wanted to use asymmetric encryption, they would need to move the private key to a remote server in order for the system to be effective. However, one of the design goals for Nintendo probably would have been to avoid a situation where a constantly available connection to the an Internet server was required. In any case, the encryption algorithm used may inflate the size of the data being encrypted, or they may pad to the size of the file for the algorithm to be more effective.
• In order for Nintendo and third-party developers to release self-contained Virtual Console games, it’s likely the emulation software is included with every game. Otherwise, if the emulator was part of the console’s on-board software library, and they decided to patch the on-board emulator sometime in the future, then they would need to re-test every released game with the new emulator. Ouch. Using a pre-installed emulator would also prevent developers from making game specific tweaks to the emulation environment.
• Finally, the game probably includes extra information for the console to display when your at the Wii main menu. For example, it would need a picture and maybe some music or sound effects for the game when shown on the main screen. If this information wasn’t stored within the file, then the Wii would need to decrypt the file every time you accessed the main menu. Given the strength of the encryption algorithm, it’s very likely the process is computationally expensive, and if you owned several Virtual Console games it would need to decrypt all of them before you could see the little preview window.

What do you think?

Categories: Hardware
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