[skybrian]

It's not a lot of data. There are other places where you could publish a small file for free, provided that you entirely trust the encryption and therefore are willing to make the file public. For example, a gist on Github.

(But personally, I wouldn't publish the encrypted file, just in case.)

[geofft]

Store it with some scheme like TripleSec https://keybase.io/triplesec/ and put it in a private gist on GitHub, so you'd need three encryption algorithms plus GitHub account security to be broken before anyone can get to it.