Nintendo knows it can't prove emulation is illegal, but its latest tactic is very effective at knocking out sources of Switch piracy

gamesradar.com:

In the wake of Yuzu's $2.4 million settlement with Nintendo, the Mario maker has redoubled its work to fight Switch emulation, but these efforts don't involve any argument that emulation itself is illegal. Instead, Nintendo is relying on an extremely specific part of a decades-old copyright law to kill a load of software that can be used to pirate Switch games.

Earlier this month, Nintendo issued a pile of takedown notices to GitHub under the Digital Millennium Copyright Act, or DMCA, as TorrentFreak reports. Two pieces of software have been the primary targets in the company's crosshairs: Lockpick and SigPatch-Updater. Lockpick is a piece of software that can extract cryptographic keys from Switch games, while SigPatch-Updater allows users to bypass the verification process for digital games. Neither one of them is new, and both have been playing a game of DMCA whack-a-mole with Nintendo for ages.

Both physical and digital Switch games include what Nintendo calls technological protection measures, or TPMs. As Nintendo itself explains in one of those takedown notices, "When a game is started on the Nintendo Switch console a Game TPM is decrypted using cryptographic keys that are protected by Console TPMs. The games themselves can then be decrypted by the decrypted Game TPMs so the game can be played."

The DMCA includes a section that says "no person shall circumvent a technological measure that effectively controls access to a work protected under this title." In other words, any attempt to bypass DRM is a violation of copyright law no matter the intent - or at least, that's how Nintendo interprets the law, and that argument has been very effective at getting hosts like GitHub to take down software like Lockpick and SigPatch-Updater.

SigPatch-Updater doesn't even actually bypass any TPMs by itself. Instead, it allows users to download SigPatches provided by external sources to bypass those checks. Nintendo argues in that takedown notice that the dev behind