I'm not even 100% certain what this involves, but my current understanding is this:
use of only approved cryptographic algorithms for network traffic (easy, we use SSL and lock down the algorithms to only the really strong ones).
Some form of physical data protection, involving disk encryption and physical tamper evident packaging.
Obviously we're on our own if we need a tamper-proof product. But what about software for encrpytion. My guess is just using LUKS (although secure) will not be certified because it's open source (gov't seems a bit biased towards proprietary solutions here).