publish-encrypted-messages.md

Publish Encrypted Messages

You can publish messages which are encrypted for up to 7 other recipients. This is done by adding the ssb-private plugin.

Private.publish

First is private.publish:

sbot.private.publish({ type: type, ... }, recps, cb)

This works exactly like sbot.publish, but recps includes a list of feed-ids to encrypted the message for. (Note, the CLI is currently not able to support this function, so it must be called programmatically.)

Private.unbox

To decode a message, you use private.unbox

sbot.private.unbox(ciphertext, cb)

An encrypted message's content attribute will be a string. So, you can see that a message is encrypted with this check:

function isEncrypted (msg) {
  return (typeof msg.value.content == 'string')
}

Private Posts

There is no way to see who an encrypted message is for. If unbox() decrypts successfully, then you'll know the message was for you.

A private post should include the recps attribute, so that the recipients know who else received the message. Example usage:

sbot.private.publish(
  {
    type: 'post', 
    text: 'secret hello!',
    recps: [
      { link: '@hxGxqPrplLjRG2vtjQL87abX4QKqeLgCwQpS730nNwE=.ed25519', name: 'paul' },
      { link: '@EMovhfIrFk4NihAKnRNhrfRaqIhBv1Wj8pTxJNgvCCY=.ed25519', name: 'dominic' }
    ]
  },
  [
    '@hxGxqPrplLjRG2vtjQL87abX4QKqeLgCwQpS730nNwE=.ed25519',
    '@EMovhfIrFk4NihAKnRNhrfRaqIhBv1Wj8pTxJNgvCCY=.ed25519'
  ],
  cb
)

Be sure to include yourself amongst the recipients and encryption targets, or you won't be able to read your own message!