Depends of your country, there's a lot of countries with interoperability exceptions to copyright, a lot of EU countries will fall in this category and it's totally legal in those countries to publish DRM hacks and publish software which circumvent such protections automatically.
The DMCA specifically acknowledges that it cannot limit free speech, and it specifically defines what is prohibited:
"No person shall manufacture, import, offer to the public, provide, or otherwise traffic in any technology, product, service, device, component, or part"