you need to also encode it with your memo key...
Currently you can do this with the cli_wallet tool if you transfer:

Apparently you can read them unencrypted through cli_wallet (logged in with memo key I guess) or right here on steemit when logged in with the memo key

You can read more about the memo key on:
https://steemit.com/steem/@dantheman/how-to-encrypt-a-memo-when-transferring-steem