> It seems like what they do (maybe?) is encrypt the binary/string data but still let you search or join on it by encrypting queries to the same data? So in other words the operations on the data are not encrypted but the data itself is?

Are you saying something along the lines of - they split the data in to tokens, deterministically (no iv) encrypt each token, and then do equality comparisons on the encrypted tokens?

Maybe, and it would explain why they say you can chose a cipher and then list a bunch of standard symmetric ciphers. However such schemes usually leak too much in practise (even at the granuality of whole words).

More importantly, it really doesn't matter. They have both the key and the encrypted data. If someone hacks their system, the best encryption in the world won't help if the attacker steals both.