Great post Matthew.

You could send it to someone in a message or email and give them the decryption passphrase in person or with another communication channel.

I just remembered that you can create a pair of keys (a public and a private key) that you can use for this intend. I mean, you encrypt your files with your private key, and then you share your file, and your public key to someone else (or to the world, depending on what you need/want to do), so whenever they receive (or download) the file, they need to use your public key to decode the file and doing this assure the people that received your file that it's integrity hasn't been violated.

Greets!