Starting with 1.12 in July 2016, Docker Swarm Mode is a built-in solution with built-in key/value store. Easier to get started, and fewer ports to configure.
This guide will demonstrate the steps required to encrypt and decrypt files using OpenSSL on Mac OS X. The working assumption is that by demonstrating how to encrypt a file with your own public key, you'll also be able to encrypt a file you plan to send to somebody else using their private key, though you may wish to use this approach to keep archived data safe from prying eyes.
Assuming you've already done the setup described later in this document, that id_rsa.pub.pcks8 is the public key you want to use, that id_rsa is the private key the recipient will use, and secret.txt is the data you want to transmit…
$ openssl rand 192 -out key
$ openssl aes-256-cbc -in secret.txt -out secret.txt.enc -pass file:key
| Rehearsal --------------------------------------------- | |
| struct 0.800000 0.110000 0.910000 ( 0.908901) | |
| api_smith 11.370000 0.030000 11.400000 ( 11.416546) | |
| virtus 62.730000 0.080000 62.810000 ( 62.869756) | |
| ----------------------------------- total: 75.120000sec | |
| user system total real | |
| struct 0.780000 0.030000 0.810000 ( 0.816881) | |
| api_smith 11.130000 0.010000 11.140000 ( 11.157779) | |
| virtus 60.450000 0.030000 60.480000 ( 60.487696) |
| Rehearsal -------------------------------------------------- | |
| &block + yield 0.960000 0.050000 1.010000 ( 1.017942) | |
| &block + call 1.080000 0.050000 1.130000 ( 1.122803) | |
| proc + call 0.270000 0.330000 0.600000 ( 0.606673) | |
| yield 0.250000 0.000000 0.250000 ( 0.244251) | |
| ----------------------------------------- total: 2.990000sec | |
| user system total real | |
| &block + yield 1.000000 0.050000 1.050000 ( 1.040755) | |
| &block + call 1.090000 0.040000 1.130000 ( 1.133808) |