Adversary is a term of art in both intelligence and cryptographic circles: it means an attacker trying to get your information/thwart your goals. . The NSA does

Adversary is a term of art in both intelligence and cryptographic circles: it means an attacker trying to get your information/thwart your goals. . The NSA does not consider normal people adversaries in that sense. Targets and potential terrorists, possibly, but actively capable of screwing with the NSA, no. If the sentence was written by a cryptographer, it most likely reads as the NSA is an adversary in the context of the cryptographic system(since they are braking it) and they want to make sure that only they and not the consumer or another intelligence service knows of their exploit.