Lockpick_RCM, the popular Switch tool to dump your Nintendo Switch decryption keys, has (as of yesterday) been taken down from Github, following a DMCA request dated last week, allegedly by Nintendo. This happens in the context of the new Zelda game release, and might be related to the keys being required for emulators to run Switch games. In the wake of this event, the developers of the Skyline Switch emulator for Android have announced they would stop working on their emulator.

What is Lockpick_RCM, and why are Nintendo going after it?

Lockpick_RCM is a tool for hacked Nintendo Switch consoles, that allows users to dump their console’s encryption/decryption keys, including the console’s unique keys. These keys are useful to decrypt/encrypt game backups, among other things. Grabbing these keys is also considered an essential step in installing Custom firmware on the console, in particular as a safety measure. In some cases, these keys might be required to reinstall a Nintendo Switch from scratch (e.g. in case of brick without a proper NAND backup).

These keys are critical to have. In an extreme emergency, they can be used in conjunction with your NAND backup and other tools to restore your console to a working state.

Beyond this, encryption keys can be needed to transfer save files (for example) between two different hacked Nintendo Switch consoles, and other fun manipulations. Generally speaking, anything that requires decrypting some user/console specific content and use it with another console or user, will probably be needing those keys. Arguably, owners of hacked consoles can use this to safely store DRM-less backups of their own games.

More commonly though, these keys are used to run game “backups”, in particular on Switch emulators. It goes without saying, but a lot of emulator users acquire these keys from other folks (friends or otherwise) in order to run their games.

In other words, although Lockpick_RCM itself, used by an individual who would keep their own keys for themselves, is basically harmless to Nintendo’s business (the legal aspect of it depends on your country and I’m not a lawyer so I won’t speak to that), sharing these keys to people who don’t own a Nintendo Switch is a critical step for these people emulating the games, potentially illegally.

To restate, in order to play a Switch game on an emulator, you need a digital copy of the game, an emulator, and the keys. The game and the keys can be acquired illegally on some download sites. If you create your own dump of keys and game with your own console, whether that is legal or not is, again, depending on your country.

Yuzu shown running Zelda Tears of the Kingdom running, a few day before the official game’s release, after a leak of a pirated version of the game

And, again, I’m no lawyer. I do believe there are very legal use cases for a tool such as Lockpick_RCM, but I think Nintendo don’t care and will push against it when they see fit, which happens to be now.

Sharing the prod keys is clearly illegal in most countries, but Lockpick_RCM itself is more of a gray area. It appears Nintendo have gone quite wide with a DMCA request that principally targeted projects that provided the keys, but Lockpick_RCM itself as well. From their DMCA notice:

The Nintendo Switch console and video games contain multiple technological protection measures (“Technological Measures”) including those that permit the Nintendo Switch console to interact only with legitimate Nintendo video game files. This process protects Nintendo’s copyright-protected video games, including but not limited to those covered by U.S. Copyright Registration numbers PA0002213509 (Super Mario Maker 2); PA0002233840 (Animal Crossing: New Horizons); PA0002213908 (Luigi’s Mansion 3); and PA0002028142 (The Legend of Zelda: Breath of the Wild) by preventing users from playing pirated copies of Nintendo’s video games on the Nintendo Switch console and by preventing users from unlawfully copying and playing Nintendo’s video games on unauthorized devices.

[…]

The reported repository offers and provides access to circumvention software that infringes Nintendo’s intellectual property rights. Specifically, the reported repository provides Lockpick to users. The use of Lockpick with a modified Nintendo Switch console allows users to bypass Nintendo’s Technological Measures for video games; specifically, Lockpick bypasses the Console TPMs to permit unauthorized access to, extraction of, and decryption of all the cryptographic keys, including product keys, contained in the Nintendo Switch. The decrypted keys facilitate copyright infringement by permitting users to play pirated versions of Nintendo’s copyright-protected game software on systems without Nintendo’s Console TPMs or systems on which Nintendo’s Console TPMs have been disabled. Trafficking in circumvention software, such as Lockpick, violates the Digital Millennium Copyright Act of the United States (specifically, 17 U.S.C. §1201), and infringes copyrights owned by Nintendo.

Although The New Zelda Tears of the Kingdom is not mentioned in the DMCA notice (the notice does mention Breath of the wild though), it has been widely circulated that Nintendo’s latest game was leaked 2 weeks prior to its actual release date, and played on emulators such as Yuzu before getting to the hands of paying customers. It is possible that Nintendo have been sending the DMCA as a mitigation, to limit piracy of their flagship 2023 game.

Lockpick_RCM itself isn’t directly a problem. The people sharing keys acquired with it are, but it’s probably easier, legally speaking, for Nintendo to go after a clearly labelled target. Technically, this feels like a moot action, as it remains very easy to find those cryptography keys online, but that’s not the only goal of the DMCA. This also sends a warning to scene developers and will have a chilling effect on many other projects.

For example, the developers of Skyline, the Switch emulator for Android, have announced they would stop developing the emulator. Download links are still available, but development has basically stopped for Skyline.

Popular emulators Yuzu and Ryujinx are still going on, but have been quite strict about not mentioning TOTK in particular lately.