ssb-tribes

A scuttlebutt plugin for managing encrypted groups. Implements the private group spec which uses the envelope spec.

This is the successor to ssb-private1.

Example Usage

const SecretStack = require('secret-stack')
const config = require('ssb-config')
const caps = require('ssb-caps')

const stack = SecretStack({ caps })
  .use(require('ssb-db2/core'))
  .use(require('ssb-classic'))
  .use(require('ssb-db2/compat'))
  .use(require('ssb-db2/compat/feedstate'))
  .use(require('ssb-box2'))
  .use(...)

const ssb = stack({
  ...config,
  box2: {
    ...config.box2,
    legacyMode: true
  }
})

ssb.tribes.create({}, (err, info) => {
  const { groupId } = info

  const content = {
    type: 'post',
    test: 'kia ora, e te whānau',
    recps: [groupId] // <<< you can now put a groupId in the recps
  }
  ssb.tribes.publish(content, (err, msg) => {
    // tada msg is encrypted to group!

    const cookie = '@YXkE3TikkY4GFMX3lzXUllRkNTbj5E+604AkaO1xbz8=.ed25519'
    const staltz = '@QlCTpvY7p9ty2yOFrv1WU1AE88aoQc4Y7wYal7PFc+w=.ed25519'

    ssb.tribes.invite(groupId, [cookie, staltz], {}, (err, invite) => {
      // two friends have been sent an invite which includes the decryption key for the group
      // they can now read the message I just published, and publish their own messages to the group

    })
  })
})

Behaviour

This plugin provides functions for creating groups and administering things about them, but it also provides a bunch of "automatic" behviour.

1. When you publish a message with recps using ssb.tribes.publish it will auto-encrypt the content when:
   • there are 1-16 FeedIds (direct mesaaging)
   • there is 1 GroupId (private group messaging)
   • there is 1 GroupId followed by 1-15 FeedId
     • NOTE this is currently only recommended for group invite messages as it's easy to leak group info
2. When you receive an encrypted message with suffix .box2 it will attempt to auto-decrypt the content:
   • on success this value will then be accessible in all database queries/ indexes
   • if it fails because it didn't have the key, the message gets passed to the next auto-decrypter to attempt
   • if it fails because something is clearly horribly wrong in the encyprtion and it should have worked, it throws an error (check this)
3. When you receive an invite to a new group, you will auto-decrypt all messages
   • we re-index your whole database, which will reveal new messages you can decrypt
     • in the future we will only re-index messages you previously could not decrypt
   • keys for groups are stored in a off-chain key-store
4. If you've been given the readKey for a particular message, you can use that
   • e.g. ssb.get({ id, private: true, key: readKey }, cb)

NOTES:

• Work on this project was resourced by Āhau. The name "tribes" was suggested by that project, and the API mostly reflects that. Some internal variables also use "group", as this is following the private group spec. You can read tribe/ group interchangeably.
• Each tribe has a <GroupId> (a unique identifier) which can be mapped to that tribe's <GroupKey> (a shared encryption key). The <GroupId> is related to the initialisation message for the tribe, but is safe to share (leaks no info about who started the group). The reason we can't use the "public" part of the <GroupKey> as an id (like <FeedId>) is that there isn't a public part - it's a symmetric key!
• <FeedId> is synonymous with the public key of a particular device (@...sha256). The private group spec details how we map this to a shared key between you (the author) and that recipient.

Requirements

A Secret-Stack server running the plugins:

• ssb-db2/core >= 7.1.1
• ssb-classic
• ssb-tribes
• ssb-db2/compat
• ssb-db2/compat/feedstate
• ssb-box2 >= 7.4.0
• ssb-replicate - (optional) used to auto-replicate people who you're in groups with

The secret stack option config.box2.legacyMode also needs to be true.

API

ssb.tribes.publish(content, cb)

A wrapper around ssb.db.create that makes sure you have correct tangles (if relevant) in your message. Mutates content. You need to put recipients in content.recps.

ssb.tribes.create(opts, cb)

Mint a new private group.

where:

• opts Object
  • opts.addPOBox Boolean attaches a P.O. Box to the group and publish the keys into the group
    • default: false
• cb Function is a callback with signature cb(err, data) where data is an Object with properties:
  • groupId String - a cipherlink that's safe to use publicly to name the group, and is used in recps to trigger enveloping messages to that group
  • groupKey Buffer - the symmetric key used for encryption by the group
  • groupInitMsg Object - a copy of the (enveloped) message used to initialise the group

This method calls group.add and group.addAuthors for you (adding you)

ssb.tribes.invite(groupId, [authorId], opts, cb)

Adds an author to a group you belong to. This publishes a message that both this new author AND the group can see, and contains the info needed to get the new person started (the groupKey and root).

where:

• groupId String - is a cloaked id for a group you're a part of
• [authorId] Array - is a collection of the feed ids of authors you're going to invite
  • NOTE: you are limited to inviting at most 15 authors per call of this method
• opts Object - is of form { text } which allows you to (optionally) post some welcoming or intruducing message along with the invte.
• cb Function - is a callback with signature cb(err, invite)

This method calls group.addAuthors for you (adding that person to the group register for you)

ssb.tribes.addNewAuthorListener(fn)

Listens for when new authors are added to a tribe, and fires a given function

• fn Function - a function to call when a new author is added to the tribe. The function receives:
  • groupId String - the id of the tribe
  • newAuthors Array - array of new authors added to the tribe

ssb.tribes.excludeMembers(groupId, [authorId], cb)

Excludes an author from a group you belong to. This publishes a message that both this new author AND the group can see. NOTE :warning: this only politely asks the author to leave the group, we don't rotate keys (yet)

where:

• groupId String - is a cloaked id for a group you're a part of
• [authorId] Array - is a collection of the feed ids of authors you're going to exclude
• cb Function - is a callback with signature cb(err, exclusion)

ssb.tribes.list(cb)

Returns a list of all known group IDs. By default this excludes subgroups

Alternatively ssb.tribes.list({ subtribes: true }, cb) will give you all group IDs (including those of subtribes)

ssb.tribes.get(groupId, cb)

Returns group metadata for a given group:

• key - the decryption key for the group
• scheme - the scheme the key is associated with (e.g. DM, group)
• root - the initial message which started the group

ssb.tribes.listAuthors(groupId, cb)

Lists all the authors (feedIds) who you know are part of the group with id groupId

ssb.tribes.subtribe.create(groupId, opts, cb)

A convenience method which:

• mints a group
• publishes a link in the parent group which advertises the existence of the subGroup
• mints a poBoxId for that group so that the parent group member can send messages to the subGroup
• then creates a link inside the existing group (linking group + subGroup)

where:

• groupId String - the id of the parent group this subGroup will be linked to
• opts Object
  • opts.addPOBox Boolean attaches a P.O. Box to the group and publish the keys into the group
    • default: false
  • opts.admin Booelan adds meta-data to the link flagging it as the admin subgroup
• cb Function is a callback with signature cb(err, data) where data is an Object with properties:
  • groupId String - a cipherlink that's safe to use publicly to name the subGroup, and is used in recps to trigger enveloping messages to that group
  • groupKey Buffer - the symmetric key used for encryption by the subGroup
  • poBoxId Buffer - the asymetric key used to encrypt messages sent from outside of the subGroup
  • groupInitMsg Object - a copy of the (enveloped) message used to initialise the subGroup

This method calls ssb.tribes.create

ssb.tribes.subtribe.get(groupId, cb)

alias of ssb.tribes.get

API (Extras)

These endpoints give you access to additional features, such as:

• registering groups:
  • ssb.tribes.register(groupId, info, cb)
• linking your feed to a group
  • ssb.tribes.link.create({ group, name }, cb)
• linking subGroups to a group
  • ssb.tribes.link.createSubGroupLink({ group, subGroup, admin }, cb)
• finding groups/ subGroups
  • ssb.tribes.findByFeedId(feedId, cb)
  • ssb.tribes.findSubGroupLinks(groupId, cb)
  • ssb.tribes.subtribe.findParentGroupLinks(subGroupId, cb)
• P.O. Box tools
  • ssb.tribes.poBox.create(opts, cb)
  • ssb.tribes.addPOBox(groupId, cb)
  • ssb.tribes.poBox.get(groupId, cb)
• self-DM keys
  • ssb.tribes.ownKeys.list(cb): returns a list of self-DM keyinfo. Always a length of 1 (only a list for historical reasons). The keyinfo has the format { key: Buffer, scheme: String }.
  • ssb.tribes.ownKeys.register(key): sets the self-DM key (buffer).
• managing people applying to join to a group
  • deprecated, please use ssb-tribes-registration
  • for the old docs, see here

ssb.tribes.register(groupId, info, cb)

Registers a new group that you have learnt about.

NOTE: mainly used internally

where:

• groupId String - is a cloaked group id (see private-group-spec/group-id/README.md)
• info Object - contains data of form { key, scheme } where:
  • key String - a 32 byte symmetric key for the group (as a base64 encoded string)
  • scheme String (optional) - a description of the key management scheme this key is part of
• cb[ Function - a callback with signature cb(err: Error, success: Boolean)

ssb.tribes.poBox.create(opts, cb)

Creates a P.O. Box key-pair, which is like a one-way group messaging setup with a public and private curve25519 keypair.

• opts Object - currently unused but still required
• cb Function is a callback with signature cb(err, data) where data is an Object with properties:
  • poBoxId String - a cipherlink that can be used in recps by anyone, to send messages only those with the secret key can open
  • public Buffer - the public part of the keypair
  • secret Buffer - the secret part of the keypair

ssb.tribes.addPOBox(groupId, cb)

Creates a P.O. Box key-pair, and publishes a message announcing those to a group. This will be heard by group members, allowing them to open messages sent to that P.O. Box

• groupId String - group to add P.O. Box to
• cb Function is a callback with signature cb(err, poBoxId)

ssb.tribes.poBox.get(groupId, cb)

Get the keypair that's attached to a group

• groupId String - group that has a P.O. Box
• cb Function is a callback with signature cb(err, { poBoxId, key })

ssb.tribes.link.create({ group, name }, cb)

Creates a message of type link/feed-group which links your feedId to a valid group. (i.e. you can only create links between your feedId and profiles at the moment)

Arguments:

• group GroupId - the id of the private group you're creating a link with (linking your scuttlebutt feed with that group)
• name String (optional) - this adds your nickname for the group
• cb Function - callback with signature (err, link) where link is the link message

Note:

• this link will be encrypted to the group you're linking to (i.e. link will have recps: [groupId])

ssb.tribes.link.createSubGroupLink({ group, subGroup, admin }, cb)

Creates a message of tyoe link/group-subGroup which links a group to a subGroup

Arguments:

• group GroupId - the id of the parent private group
• subGroup GroupId - the id of the subGroup you're linking to group
• admin Boolean - when set to true, this flag is used to tell when a subgroup is the admin-only subgroup for the group
• cb - Function - call with signature (err, link) where link is the link message Note:
• this link will be encrypted to the parent group (i.e. link will have recps: [group])

ssb.tribes.findByFeedId(feedId, cb)

Find groups which have linked with a feedId (see ssb.tribes.link.create).

• feedId FeedId is a string
• cb function is a callback with signature cb(err, data) where data is an Array of items of form:

  {
    groupId: GroupId,
    recps: Recps, // an array of recipients who know about this link (should just be the group)
    states: [
      {
        head: MsgId,
        state: {
          name: null|String
        }
      }
    ]
  }

NOTE: the strange format with states is to leave easy support for multiple editors (of a link to a group) in the future

ssb.tribes.findSubGroupLinks(groupId, cb)

Find subGroups which have linked with a groupId (see ssb.tribes.link.createSubGroupLink).

• groupId GroupId is a string representing the groupId of the parent group
• cb function is a callback with signature cb(err, data) where data is an Array of items of form:

  [{
    linkId: MsgId,
    groupId: GroupId,
    subGroupId: GroupId,
    admin: Boolean,
    recps: Recps, // an array of recipients who know about this link (should just be the group)
  }]

ssb.tribes.subtribe.findParentGroupLinks(subGroupId, cb)

Find subGroups which have linked with a groupId (see ssb.tribes.link.createSubGroupLink).

• subGroupId GroupId is a string representing the groupId of the subGroup
• cb function is a callback with signature cb(err, data) where data is an Array of items of form:

  [{
    linkId: MsgId,
    groupId: GroupId, // the parent group
    subGroupId: GroupId,
    recps: Recps, // an array of recipients who know about this link (should just be the group)
  }]

TODO

• [ ] add the latest known "sequence" at time of add-member, so we know if we need to reindex!