instal GNU Privacy Guard

sudo apt-get install gnupg

Generate key

gpg --gen-key

Generate key on second computer

Export key on the second machine

gpg --export --armor [email protected] > pubkey.asc

put pubkey.asc in the working directory on the first machine

Import key on the first machine

gpg --import pubkey.asc

// Make sure it imported correctly

gpg --list-keys

// you should see 2 records or more

Install ipfs from https://ipfs.io/docs/install/

ipfs init

ipfs daemon

Repeat this at the second machine

Encrypt file and add it to IPFS

// encrypting file with public key of recipient
gpg --encrypt --recipient "Full Name of recipient" exmaple_file.pdf

// make sure that file example_file.pdf.pgp appeard at your working dirrectory

// adding file to IPFS
ipfs add example_file.pdf.pgp

// you must see output like 
added QmUAPHhxcTcQKiAFSRjcUbpge9UDyiL5NVyrKFJaXgATKv example_file.pdf.gpg

Dowload and decrypt file from ipfs on second computer

ipfs get QmUAPHhxcTcQKiAFSRjcUbpge9UDyiL5NVyrKFJaXgATKv

// make sure file QmUAPHhxcTcQKiAFSRjcUbpge9UDyiL5NVyrKFJaXgATKv appeared in working directory

gpg --decrypt QmUAPHhxcTcQKiAFSRjcUbpge9UDyiL5NVyrKFJaXgATKv > example_file.pdf

// you will see output like
You need a passphrase to unlock the secret key for
user: "Bogdan (IPFS key) <[email protected]>"
2048-bit RSA key, ID 97F5155F, created 2018-04-17 (main key ID 06E5DB59)

Enter passphrase:
// enter password which you used when creating key file

Well done, you have encrypted, uploaded, downloaded and decrypted file with IPFS and Cryptography