Fair use is irrelevant to the anti-circumvention provisions (at least unless the Library of Congress explicitly sets out an exception, and they have not for emu

Fair use is irrelevant to the anti-circumvention provisions (at least unless the Library of Congress explicitly sets out an exception, and they have not for emulation), and the statement that encryption is fair use is significantly more ambiguous than people hope it is (for a start neither of the relevant cases were heard in a high enough court to establish a significant precedent).