I would imagine it means creating a rainbow table for a particular set of prime numbers.  From the article it sounds like many applications use a small handful of prime numbers.  A DH key exchange uses two prime numbers (shared publicly) and two secrets (kept, secret...).<p>In theory the NSA could enumerate ginormous rainbow tables for a large set of secret keys.<p>Perhaps someone else on HN can provide a more detailed description of the suspected attack?<p>Edit:  the responses to smegel&#x27;s question below seem much mor e thorough and accurate than mine!