I'd be surprised if the courts actually held that implementing an algorithm was an act of circumvention. I expect they'd rather hold that to be in violation of a different paragraph:

> (2) No person shall manufacture, import, offer to the public, provide, or otherwise traffic in any technology, product, service, device, component, or part thereof, that—

> (A) is primarily designed or produced for the purpose of circumventing a technological measure that effectively controls access to a work protected under this title;

An implementation of the algorithm without the necessary key would still be a "component, or part thereof".