Add E2EE API (#13820)

Gemfile

@@ -50,6 +50,7 @@ gem 'omniauth', '~> 1.9'
 
 gem 'discard', '~> 1.2'
 gem 'doorkeeper', '~> 5.4'
+gem 'ed25519', '~> 1.2'
 gem 'fast_blank', '~> 1.0'
 gem 'fastimage'
 gem 'goldfinger', '~> 2.1'

Gemfile.lock

@@ -201,6 +201,7 @@ GEM
       dotenv (= 2.7.5)
       railties (>= 3.2, < 6.1)
     e2mmap (0.1.0)
+    ed25519 (1.2.4)
     elasticsearch (7.7.0)
       elasticsearch-api (= 7.7.0)
       elasticsearch-transport (= 7.7.0)
@@ -701,6 +702,7 @@ DEPENDENCIES
   doorkeeper (~> 5.4)
   dotenv-rails (~> 2.7)
   e2mmap (~> 0.1.0)
+  ed25519 (~> 1.2)
   fabrication (~> 2.21)
   faker (~> 2.12)
   fast_blank (~> 1.0)

app/controllers/activitypub/claims_controller.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+class ActivityPub::ClaimsController < ActivityPub::BaseController
+  include SignatureVerification
+  include AccountOwnedConcern
+
+  skip_before_action :authenticate_user!
+
+  before_action :require_signature!
+  before_action :set_claim_result
+
+  def create
+    render json: @claim_result, serializer: ActivityPub::OneTimeKeySerializer
+  end
+
+  private
+
+  def set_claim_result
+    @claim_result = ::Keys::ClaimService.new.call(@account.id, params[:id])
+  end
+end

app/controllers/activitypub/collections_controller.rb

@@ -5,8 +5,9 @@ class ActivityPub::CollectionsController < ActivityPub::BaseController
   include AccountOwnedConcern
 
   before_action :require_signature!, if: :authorized_fetch_mode?
+  before_action :set_items
   before_action :set_size
-  before_action :set_statuses
+  before_action :set_type
   before_action :set_cache_headers
 
   def show
@@ -16,40 +17,53 @@ class ActivityPub::CollectionsController < ActivityPub::BaseController
 
   private
 
-  def set_statuses
-    @statuses = scope_for_collection
-    @statuses = cache_collection(@statuses, Status)
-  end
-
-  def set_size
+  def set_items
     case params[:id]
     when 'featured'
-      @size = @account.pinned_statuses.count
+      @items = begin
+        # Because in public fetch mode we cache the response, there would be no
+        # benefit from performing the check below, since a blocked account or domain
+        # would likely be served the cache from the reverse proxy anyway
+
+        if authorized_fetch_mode? && !signed_request_account.nil? && (@account.blocking?(signed_request_account) || (!signed_request_account.domain.nil? && @account.domain_blocking?(signed_request_account.domain)))
+          []
+        else
+          cache_collection(@account.pinned_statuses, Status)
+        end
+      end
+    when 'devices'
+      @items = @account.devices
     else
       not_found
     end
   end
 
-  def scope_for_collection
+  def set_size
+    case params[:id]
+    when 'featured', 'devices'
+      @size = @items.size
+    else
+      not_found
+    end
+  end
+
+  def set_type
     case params[:id]
     when 'featured'
-      # Because in public fetch mode we cache the response, there would be no
-      # benefit from performing the check below, since a blocked account or domain
-      # would likely be served the cache from the reverse proxy anyway
-      if authorized_fetch_mode? && !signed_request_account.nil? && (@account.blocking?(signed_request_account) || (!signed_request_account.domain.nil? && @account.domain_blocking?(signed_request_account.domain)))
-        Status.none
-      else
-        @account.pinned_statuses
-      end
+      @type = :ordered
+    when 'devices'
+      @type = :unordered
+    else
+      not_found
     end
   end
 
   def collection_presenter
     ActivityPub::CollectionPresenter.new(
       id: account_collection_url(@account, params[:id]),
-      type: :ordered,
+      type: @type,
       size: @size,
-      items: @statuses
+      items: @items
     )
   end
 end

app/controllers/api/v1/crypto/deliveries_controller.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+class Api::V1::Crypto::DeliveriesController < Api::BaseController
+  before_action -> { doorkeeper_authorize! :crypto }
+  before_action :require_user!
+  before_action :set_current_device
+
+  def create
+    devices.each do |device_params|
+      DeliverToDeviceService.new.call(current_account, @current_device, device_params)
+    end
+
+    render_empty
+  end
+
+  private
+
+  def set_current_device
+    @current_device = Device.find_by!(access_token: doorkeeper_token)
+  end
+
+  def resource_params
+    params.require(:device)
+    params.permit(device: [:account_id, :device_id, :type, :body, :hmac])
+  end
+
+  def devices
+    Array(resource_params[:device])
+  end
+end

app/controllers/api/v1/crypto/encrypted_messages_controller.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+class Api::V1::Crypto::EncryptedMessagesController < Api::BaseController
+  LIMIT = 80
+
+  before_action -> { doorkeeper_authorize! :crypto }
+  before_action :require_user!
+  before_action :set_current_device
+
+  before_action :set_encrypted_messages,    only: :index
+  after_action  :insert_pagination_headers, only: :index
+
+  def index
+    render json: @encrypted_messages, each_serializer: REST::EncryptedMessageSerializer
+  end
+
+  def clear
+    @current_device.encrypted_messages.up_to(params[:up_to_id]).delete_all
+    render_empty
+  end
+
+  private
+
+  def set_current_device
+    @current_device = Device.find_by!(access_token: doorkeeper_token)
+  end
+
+  def set_encrypted_messages
+    @encrypted_messages = @current_device.encrypted_messages.paginate_by_id(limit_param(LIMIT), params_slice(:max_id, :since_id, :min_id))
+  end
+
+  def insert_pagination_headers
+    set_pagination_headers(next_path, prev_path)
+  end
+
+  def next_path
+    api_v1_encrypted_messages_url pagination_params(max_id: pagination_max_id) if records_continue?
+  end
+
+  def prev_path
+    api_v1_encrypted_messages_url pagination_params(min_id: pagination_since_id) unless @encrypted_messages.empty?
+  end
+
+  def pagination_max_id
+    @encrypted_messages.last.id
+  end
+
+  def pagination_since_id
+    @encrypted_messages.first.id
+  end
+
+  def records_continue?
+    @encrypted_messages.size == limit_param(LIMIT)
+  end
+
+  def pagination_params(core_params)
+    params.slice(:limit).permit(:limit).merge(core_params)
+  end
+end

app/controllers/api/v1/crypto/keys/claims_controller.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+class Api::V1::Crypto::Keys::ClaimsController < Api::BaseController
+  before_action -> { doorkeeper_authorize! :crypto }
+  before_action :require_user!
+  before_action :set_claim_results
+
+  def create
+    render json: @claim_results, each_serializer: REST::Keys::ClaimResultSerializer
+  end
+
+  private
+
+  def set_claim_results
+    @claim_results = devices.map { |device_params| ::Keys::ClaimService.new.call(current_account, device_params[:account_id], device_params[:device_id]) }.compact
+  end
+
+  def resource_params
+    params.permit(device: [:account_id, :device_id])
+  end
+
+  def devices
+    Array(resource_params[:device])
+  end
+end

app/controllers/api/v1/crypto/keys/counts_controller.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class Api::V1::Crypto::Keys::CountsController < Api::BaseController
+  before_action -> { doorkeeper_authorize! :crypto }
+  before_action :require_user!
+  before_action :set_current_device
+
+  def show
+    render json: { one_time_keys: @current_device.one_time_keys.count }
+  end
+
+  private
+
+  def set_current_device
+    @current_device = Device.find_by!(access_token: doorkeeper_token)
+  end
+end

app/controllers/api/v1/crypto/keys/queries_controller.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+class Api::V1::Crypto::Keys::QueriesController < Api::BaseController
+  before_action -> { doorkeeper_authorize! :crypto }
+  before_action :require_user!
+  before_action :set_accounts
+  before_action :set_query_results
+
+  def create
+    render json: @query_results, each_serializer: REST::Keys::QueryResultSerializer
+  end
+
+  private
+
+  def set_accounts
+    @accounts = Account.where(id: account_ids).includes(:devices)
+  end
+
+  def set_query_results
+    @query_results = @accounts.map { |account| ::Keys::QueryService.new.call(account) }.compact
+  end
+
+  def account_ids
+    Array(params[:id]).map(&:to_i)
+  end
+end

app/controllers/api/v1/crypto/keys/uploads_controller.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+class Api::V1::Crypto::Keys::UploadsController < Api::BaseController
+  before_action -> { doorkeeper_authorize! :crypto }
+  before_action :require_user!
+
+  def create
+    device = Device.find_or_initialize_by(access_token: doorkeeper_token)
+
+    device.transaction do
+      device.account = current_account
+      device.update!(resource_params[:device])
+
+      if resource_params[:one_time_keys].present? && resource_params[:one_time_keys].is_a?(Enumerable)
+        resource_params[:one_time_keys].each do |one_time_key_params|
+          device.one_time_keys.create!(one_time_key_params)
+        end
+      end
+    end
+
+    render json: device, serializer: REST::Keys::DeviceSerializer
+  end
+
+  private
+
+  def resource_params
+    params.permit(device: [:device_id, :name, :fingerprint_key, :identity_key], one_time_keys: [:key_id, :key, :signature])
+  end
+end

app/controllers/statuses_controller.rb

@@ -42,7 +42,7 @@ class StatusesController < ApplicationController
 
   def activity
     expires_in 3.minutes, public: @status.distributable? && public_fetch_mode?
-    render_with_cache json: @status, content_type: 'application/activity+json', serializer: ActivityPub::ActivitySerializer, adapter: ActivityPub::Adapter
+    render_with_cache json: ActivityPub::ActivityPresenter.from_status(@status), content_type: 'application/activity+json', serializer: ActivityPub::ActivitySerializer, adapter: ActivityPub::Adapter
   end
 
   def embed

app/lib/activitypub/activity/create.rb

@@ -2,6 +2,45 @@
 
 class ActivityPub::Activity::Create < ActivityPub::Activity
   def perform
+    case @object['type']
+    when 'EncryptedMessage'
+      create_encrypted_message
+    else
+      create_status
+    end
+  end
+
+  private
+
+  def create_encrypted_message
+    return reject_payload! if invalid_origin?(@object['id']) || @options[:delivered_to_account_id].blank?
+
+    target_account = Account.find(@options[:delivered_to_account_id])
+    target_device  = target_account.devices.find_by(device_id: @object.dig('to', 'deviceId'))
+
+    return if target_device.nil?
+
+    target_device.encrypted_messages.create!(
+      from_account: @account,
+      from_device_id: @object.dig('attributedTo', 'deviceId'),
+      type: @object['messageType'],
+      body: @object['cipherText'],
+      digest: @object.dig('digest', 'digestValue'),
+      message_franking: message_franking.to_token
+    )
+  end
+
+  def message_franking
+    MessageFranking.new(
+      hmac: @object.dig('digest', 'digestValue'),
+      original_franking: @object['messageFranking'],
+      source_account_id: @account.id,
+      target_account_id: @options[:delivered_to_account_id],
+      timestamp: Time.now.utc
+    )
+  end
+
+  def create_status
     return reject_payload! if unsupported_object_type? || invalid_origin?(@object['id']) || Tombstone.exists?(uri: @object['id']) || !related_to_local_activity?
 
     RedisLock.acquire(lock_options) do |lock|
@@ -23,8 +62,6 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
     @status
   end
 
-  private
-
   def audience_to
     @object['to'] || @json['to']
   end
@@ -262,6 +299,7 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
   def poll_vote!
     poll = replied_to_status.preloadable_poll
     already_voted = true
+
     RedisLock.acquire(poll_lock_options) do |lock|
       if lock.acquired?
         already_voted = poll.votes.where(account: @account).exists?
@@ -270,20 +308,24 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
         raise Mastodon::RaceConditionError
       end
     end
+
     increment_voters_count! unless already_voted
     ActivityPub::DistributePollUpdateWorker.perform_in(3.minutes, replied_to_status.id) unless replied_to_status.preloadable_poll.hide_totals?
   end
 
   def resolve_thread(status)
     return unless status.reply? && status.thread.nil? && Request.valid_url?(in_reply_to_uri)
+
     ThreadResolveWorker.perform_async(status.id, in_reply_to_uri)
   end
 
   def fetch_replies(status)
     collection = @object['replies']
     return if collection.nil?
+
     replies = ActivityPub::FetchRepliesService.new.call(status, collection, false)
     return unless replies.nil?
+
     uri = value_or_id(collection)
     ActivityPub::FetchRepliesWorker.perform_async(status.id, uri) unless uri.nil?
   end
@@ -291,6 +333,7 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
   def conversation_from_uri(uri)
     return nil if uri.nil?
     return Conversation.find_by(id: OStatus::TagManager.instance.unique_tag_to_local_id(uri, 'Conversation')) if OStatus::TagManager.instance.local_id?(uri)
+
     begin
       Conversation.find_or_create_by!(uri: uri)
     rescue ActiveRecord::RecordInvalid, ActiveRecord::RecordNotUnique
@@ -404,6 +447,7 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
 
   def skip_download?
     return @skip_download if defined?(@skip_download)
+
     @skip_download ||= DomainBlock.reject_media?(@account.domain)
   end
 
@@ -436,11 +480,13 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
 
   def forward_for_reply
     return unless @json['signature'].present? && reply_to_local?
+
     ActivityPub::RawDistributionWorker.perform_async(Oj.dump(@json), replied_to_status.account_id, [@account.preferred_inbox_url])
   end
 
   def increment_voters_count!
     poll = replied_to_status.preloadable_poll
+
     unless poll.voters_count.nil?
       poll.voters_count = poll.voters_count + 1
       poll.save

app/lib/activitypub/adapter.rb

@@ -22,6 +22,7 @@ class ActivityPub::Adapter < ActiveModelSerializers::Adapter::Base
     blurhash: { 'toot' => 'http://joinmastodon.org/ns#', 'blurhash' => 'toot:blurhash' },
     discoverable: { 'toot' => 'http://joinmastodon.org/ns#', 'discoverable' => 'toot:discoverable' },
     voters_count: { 'toot' => 'http://joinmastodon.org/ns#', 'votersCount' => 'toot:votersCount' },
+    olm: { 'toot' => 'http://joinmastodon.org/ns#', 'Device' => 'toot:Device', 'Ed25519Signature' => 'toot:Ed25519Signature', 'Ed25519Key' => 'toot:Ed25519Key', 'Curve25519Key' => 'toot:Curve25519Key', 'EncryptedMessage' => 'toot:EncryptedMessage', 'publicKeyBase64' => 'toot:publicKeyBase64', 'deviceId' => 'toot:deviceId', 'claim' => { '@type' => '@id', '@id' => 'toot:claim' }, 'fingerprintKey' => { '@type' => '@id', '@id' => 'toot:fingerprintKey' }, 'identityKey' => { '@type' => '@id', '@id' => 'toot:identityKey' }, 'devices' => { '@type' => '@id', '@id' => 'toot:devices' }, 'messageFranking' => 'toot:messageFranking', 'messageType' => 'toot:messageType', 'cipherText' => 'toot:cipherText' },
   }.freeze
 
   def self.default_key_transform

app/lib/inline_renderer.rb

@@ -19,6 +19,8 @@ class InlineRenderer
       serializer = REST::AnnouncementSerializer
     when :reaction
       serializer = REST::ReactionSerializer
+    when :encrypted_message
+      serializer = REST::EncryptedMessageSerializer
     else
       return
     end

app/models/account.rb

@@ -49,6 +49,7 @@
 #  hide_collections              :boolean
 #  avatar_storage_schema_version :integer
 #  header_storage_schema_version :integer
+#  devices_url                   :string
 #
 
 class Account < ApplicationRecord

app/models/concerns/account_associations.rb

@@ -9,6 +9,7 @@ module AccountAssociations
 
     # Identity proofs
     has_many :identity_proofs, class_name: 'AccountIdentityProof', dependent: :destroy, inverse_of: :account
+    has_many :devices, dependent: :destroy, inverse_of: :account
 
     # Timelines
     has_many :statuses, inverse_of: :account, dependent: :destroy

app/models/device.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+# == Schema Information
+#
+# Table name: devices
+#
+#  id              :bigint(8)        not null, primary key
+#  access_token_id :bigint(8)
+#  account_id      :bigint(8)
+#  device_id       :string           default(""), not null
+#  name            :string           default(""), not null
+#  fingerprint_key :text             default(""), not null
+#  identity_key    :text             default(""), not null
+#  created_at      :datetime         not null
+#  updated_at      :datetime         not null
+#
+
+class Device < ApplicationRecord
+  belongs_to :access_token, class_name: 'Doorkeeper::AccessToken'
+  belongs_to :account
+
+  has_many :one_time_keys, dependent: :destroy, inverse_of: :device
+  has_many :encrypted_messages, dependent: :destroy, inverse_of: :device
+
+  validates :name, :fingerprint_key, :identity_key, presence: true
+  validates :fingerprint_key, :identity_key, ed25519_key: true
+
+  before_save :invalidate_associations, if: -> { device_id_changed? || fingerprint_key_changed? || identity_key_changed? }
+
+  private
+
+  def invalidate_associations
+    one_time_keys.destroy_all
+    encrypted_messages.destroy_all
+  end
+end

app/models/encrypted_message.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+# == Schema Information
+#
+# Table name: encrypted_messages
+#
+#  id               :bigint(8)        not null, primary key
+#  device_id        :bigint(8)
+#  from_account_id  :bigint(8)
+#  from_device_id   :string           default(""), not null
+#  type             :integer          default(0), not null
+#  body             :text             default(""), not null
+#  digest           :text             default(""), not null
+#  message_franking :text             default(""), not null
+#  created_at       :datetime         not null
+#  updated_at       :datetime         not null
+#
+
+class EncryptedMessage < ApplicationRecord
+  self.inheritance_column = nil
+
+  include Paginable
+
+  scope :up_to, ->(id) { where(arel_table[:id].lteq(id)) }
+
+  belongs_to :device
+  belongs_to :from_account, class_name: 'Account'
+
+  around_create Mastodon::Snowflake::Callbacks
+
+  after_commit :push_to_streaming_api
+
+  private
+
+  def push_to_streaming_api
+    Rails.logger.info(streaming_channel)
+    Rails.logger.info(subscribed_to_timeline?)
+
+    return if destroyed? || !subscribed_to_timeline?
+
+    PushEncryptedMessageWorker.perform_async(id)
+  end
+
+  def subscribed_to_timeline?
+    Redis.current.exists("subscribed:#{streaming_channel}")
+  end
+
+  def streaming_channel
+    "timeline:#{device.account_id}:#{device.device_id}"
+  end
+end

app/models/message_franking.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class MessageFranking
+  attr_reader :hmac, :source_account_id, :target_account_id,
+              :timestamp, :original_franking
+
+  def initialize(attributes = {})
+    @hmac              = attributes[:hmac]
+    @source_account_id = attributes[:source_account_id]
+    @target_account_id = attributes[:target_account_id]
+    @timestamp         = attributes[:timestamp]
+    @original_franking = attributes[:original_franking]
+  end
+
+  def to_token
+    crypt = ActiveSupport::MessageEncryptor.new(SystemKey.current_key, serializer: Oj)
+    crypt.encrypt_and_sign(self)
+  end
+end

app/models/one_time_key.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+# == Schema Information
+#
+# Table name: one_time_keys
+#
+#  id         :bigint(8)        not null, primary key
+#  device_id  :bigint(8)
+#  key_id     :string           default(""), not null
+#  key        :text             default(""), not null
+#  signature  :text             default(""), not null
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+
+class OneTimeKey < ApplicationRecord
+  belongs_to :device
+
+  validates :key_id, :key, :signature, presence: true
+  validates :key, ed25519_key: true
+  validates :signature, ed25519_signature: { message: :key, verify_key: ->(one_time_key) { one_time_key.device.fingerprint_key } }
+end

app/models/system_key.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: system_keys
+#
+#  id         :bigint(8)        not null, primary key
+#  key        :binary
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+class SystemKey < ApplicationRecord
+  ROTATION_PERIOD = 1.week.freeze
+
+  before_validation :set_key
+
+  scope :expired, ->(now = Time.now.utc) { where(arel_table[:created_at].lt(now - ROTATION_PERIOD * 3)) }
+
+  class << self
+    def current_key
+      previous_key = order(id: :asc).last
+
+      if previous_key && previous_key.created_at >= ROTATION_PERIOD.ago
+        previous_key.key
+      else
+        create.key
+      end
+    end
+  end
+
+  private
+
+  def set_key
+    return if key.present?
+
+    cipher = OpenSSL::Cipher.new('AES-256-GCM')
+    cipher.encrypt
+
+    self.key = cipher.random_key
+  end
+end

app/presenters/activitypub/activity_presenter.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+class ActivityPub::ActivityPresenter < ActiveModelSerializers::Model
+  attributes :id, :type, :actor, :published, :to, :cc, :virtual_object
+
+  class << self
+    def from_status(status)
+      new.tap do |presenter|
+        presenter.id        = ActivityPub::TagManager.instance.activity_uri_for(status)
+        presenter.type      = status.reblog? ? 'Announce' : 'Create'
+        presenter.actor     = ActivityPub::TagManager.instance.uri_for(status.account)
+        presenter.published = status.created_at
+        presenter.to        = ActivityPub::TagManager.instance.to(status)
+        presenter.cc        = ActivityPub::TagManager.instance.cc(status)
+
+        presenter.virtual_object = begin
+          if status.reblog?
+            if status.account == status.proper.account && status.proper.private_visibility? && status.local?
+              status.proper
+            else
+              ActivityPub::TagManager.instance.uri_for(status.proper)
+            end
+          else
+            status.proper
+          end
+        end
+      end
+    end
+
+    def from_encrypted_message(encrypted_message)
+      new.tap do |presenter|
+        presenter.id = ActivityPub::TagManager.instance.generate_uri_for(nil)
+        presenter.type = 'Create'
+        presenter.actor = ActivityPub::TagManager.instance.uri_for(encrypted_message.source_account)
+        presenter.published = Time.now.utc
+        presenter.to = ActivityPub::TagManager.instance.uri_for(encrypted_message.target_account)
+        presenter.virtual_object = encrypted_message
+      end
+    end
+  end
+end

app/serializers/activitypub/activity_serializer.rb

@@ -1,52 +1,22 @@
 # frozen_string_literal: true
 
 class ActivityPub::ActivitySerializer < ActivityPub::Serializer
+  def self.serializer_for(model, options)
+    case model.class.name
+    when 'Status'
+      ActivityPub::NoteSerializer
+    when 'DeliverToDeviceService::EncryptedMessage'
+      ActivityPub::EncryptedMessageSerializer
+    else
+      super
+    end
+  end
+
   attributes :id, :type, :actor, :published, :to, :cc
 
-  has_one :proper, key: :object, serializer: ActivityPub::NoteSerializer, if: :serialize_object?
-
-  attribute :proper_uri, key: :object, unless: :serialize_object?
-  attribute :atom_uri, if: :announce?
-
-  def id
-    ActivityPub::TagManager.instance.activity_uri_for(object)
-  end
-
-  def type
-    announce? ? 'Announce' : 'Create'
-  end
-
-  def actor
-    ActivityPub::TagManager.instance.uri_for(object.account)
-  end
+  has_one :virtual_object, key: :object
 
   def published
-    object.created_at.iso8601
-  end
-
-  def to
-    ActivityPub::TagManager.instance.to(object)
-  end
-
-  def cc
-    ActivityPub::TagManager.instance.cc(object)
-  end
-
-  def proper_uri
-    ActivityPub::TagManager.instance.uri_for(object.proper)
-  end
-
-  def atom_uri
-    OStatus::TagManager.instance.uri_for(object)
-  end
-
-  def announce?
-    object.reblog?
-  end
-
-  def serialize_object?
-    return true unless announce?
-    # Serialize private self-boosts of local toots
-    object.account == object.proper.account && object.proper.private_visibility? && object.local?
+    object.published.iso8601
   end
 end

app/serializers/activitypub/actor_serializer.rb

@@ -7,7 +7,7 @@ class ActivityPub::ActorSerializer < ActivityPub::Serializer
 
   context_extensions :manually_approves_followers, :featured, :also_known_as,
                      :moved_to, :property_value, :identity_proof,
-                     :discoverable
+                     :discoverable, :olm
 
   attributes :id, :type, :following, :followers,
              :inbox, :outbox, :featured,
@@ -20,6 +20,7 @@ class ActivityPub::ActorSerializer < ActivityPub::Serializer
   has_many :virtual_tags, key: :tag
   has_many :virtual_attachments, key: :attachment
 
+  attribute :devices, unless: :instance_actor?
   attribute :moved_to, if: :moved?
   attribute :also_known_as, if: :also_known_as?
 
@@ -38,7 +39,7 @@ class ActivityPub::ActorSerializer < ActivityPub::Serializer
   has_one :icon,  serializer: ActivityPub::ImageSerializer, if: :avatar_exists?
   has_one :image, serializer: ActivityPub::ImageSerializer, if: :header_exists?
 
-  delegate :moved?, to: :object
+  delegate :moved?, :instance_actor?, to: :object
 
   def id
     object.instance_actor? ? instance_actor_url : account_url(object)
@@ -68,6 +69,10 @@ class ActivityPub::ActorSerializer < ActivityPub::Serializer
     object.instance_actor? ? instance_actor_inbox_url : account_inbox_url(object)
   end
 
+  def devices
+    account_collection_url(object, :devices)
+  end
+
   def outbox
     account_outbox_url(object)
   end

app/serializers/activitypub/collection_serializer.rb

@@ -2,9 +2,16 @@
 
 class ActivityPub::CollectionSerializer < ActivityPub::Serializer
   def self.serializer_for(model, options)
-    return ActivityPub::NoteSerializer if model.class.name == 'Status'
-    return ActivityPub::CollectionSerializer if model.class.name == 'ActivityPub::CollectionPresenter'
-    super
+    case model.class.name
+    when 'Status'
+      ActivityPub::NoteSerializer
+    when 'Device'
+      ActivityPub::DeviceSerializer
+    when 'ActivityPub::CollectionPresenter'
+      ActivityPub::CollectionSerializer
+    else
+      super
+    end
   end
 
   attribute :id, if: -> { object.id.present? }

app/serializers/activitypub/device_serializer.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+class ActivityPub::DeviceSerializer < ActivityPub::Serializer
+  context_extensions :olm
+
+  include RoutingHelper
+
+  class FingerprintKeySerializer < ActivityPub::Serializer
+    attributes :type, :public_key_base64
+
+    def type
+      'Ed25519Key'
+    end
+
+    def public_key_base64
+      object.fingerprint_key
+    end
+  end
+
+  class IdentityKeySerializer < ActivityPub::Serializer
+    attributes :type, :public_key_base64
+
+    def type
+      'Curve25519Key'
+    end
+
+    def public_key_base64
+      object.identity_key
+    end
+  end
+
+  attributes :device_id, :type, :name, :claim
+
+  has_one :fingerprint_key, serializer: FingerprintKeySerializer
+  has_one :identity_key, serializer: IdentityKeySerializer
+
+  def type
+    'Device'
+  end
+
+  def claim
+    account_claim_url(object.account, id: object.device_id)
+  end
+
+  def fingerprint_key
+    object
+  end
+
+  def identity_key
+    object
+  end
+end

app/serializers/activitypub/encrypted_message_serializer.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+class ActivityPub::EncryptedMessageSerializer < ActivityPub::Serializer
+  context :security
+
+  context_extensions :olm
+
+  class DeviceSerializer < ActivityPub::Serializer
+    attributes :type, :device_id
+
+    def type
+      'Device'
+    end
+
+    def device_id
+      object
+    end
+  end
+
+  class DigestSerializer < ActivityPub::Serializer
+    attributes :type, :digest_algorithm, :digest_value
+
+    def type
+      'Digest'
+    end
+
+    def digest_algorithm
+      'http://www.w3.org/2000/09/xmldsig#hmac-sha256'
+    end
+
+    def digest_value
+      object
+    end
+  end
+
+  attributes :type, :message_type, :cipher_text, :message_franking
+
+  has_one :attributed_to, serializer: DeviceSerializer
+  has_one :to, serializer: DeviceSerializer
+  has_one :digest, serializer: DigestSerializer
+
+  def type
+    'EncryptedMessage'
+  end
+
+  def attributed_to
+    object.source_device.device_id
+  end
+
+  def to
+    object.target_device_id
+  end
+
+  def message_type
+    object.type
+  end
+
+  def cipher_text
+    object.body
+  end
+end

app/serializers/activitypub/one_time_key_serializer.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+class ActivityPub::OneTimeKeySerializer < ActivityPub::Serializer
+  context :security
+
+  context_extensions :olm
+
+  class SignatureSerializer < ActivityPub::Serializer
+    attributes :type, :signature_value
+
+    def type
+      'Ed25519Signature'
+    end
+
+    def signature_value
+      object.signature
+    end
+  end
+
+  attributes :key_id, :type, :public_key_base64
+
+  has_one :signature, serializer: SignatureSerializer
+
+  def type
+    'Curve25519Key'
+  end
+
+  def public_key_base64
+    object.key
+  end
+
+  def signature
+    object
+  end
+end

app/serializers/activitypub/outbox_serializer.rb

@@ -2,7 +2,14 @@
 
 class ActivityPub::OutboxSerializer < ActivityPub::CollectionSerializer
   def self.serializer_for(model, options)
-    return ActivityPub::ActivitySerializer if model.is_a?(Status)
-    super
+    if model.class.name == 'ActivityPub::ActivityPresenter'
+      ActivityPub::ActivitySerializer
+    else
+      super
+    end
+  end
+
+  def items
+    object.items.map { |status| ActivityPub::ActivityPresenter.from_status(status) }
   end
 end

app/serializers/activitypub/undo_announce_serializer.rb

@@ -3,7 +3,7 @@
 class ActivityPub::UndoAnnounceSerializer < ActivityPub::Serializer
   attributes :id, :type, :actor, :to
 
-  has_one :object, serializer: ActivityPub::ActivitySerializer
+  has_one :virtual_object, key: :object, serializer: ActivityPub::ActivitySerializer
 
   def id
     [ActivityPub::TagManager.instance.uri_for(object.account), '#announces/', object.id, '/undo'].join
@@ -20,4 +20,8 @@ class ActivityPub::UndoAnnounceSerializer < ActivityPub::Serializer
   def to
     [ActivityPub::TagManager::COLLECTIONS[:public]]
   end
+
+  def virtual_object
+    ActivityPub::ActivityPresenter.from_status(object)
+  end
 end

app/serializers/rest/encrypted_message_serializer.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+class REST::EncryptedMessageSerializer < ActiveModel::Serializer
+  attributes :id, :account_id, :device_id,
+             :type, :body, :digest, :message_franking
+
+  def id
+    object.id.to_s
+  end
+
+  def account_id
+    object.from_account_id.to_s
+  end
+
+  def device_id
+    object.from_device_id
+  end
+end

app/serializers/rest/keys/claim_result_serializer.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class REST::Keys::ClaimResultSerializer < ActiveModel::Serializer
+  attributes :account_id, :device_id, :key_id, :key, :signature
+
+  def account_id
+    object.account.id.to_s
+  end
+end

app/serializers/rest/keys/device_serializer.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+class REST::Keys::DeviceSerializer < ActiveModel::Serializer
+  attributes :device_id, :name, :identity_key,
+             :fingerprint_key
+end

app/serializers/rest/keys/query_result_serializer.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class REST::Keys::QueryResultSerializer < ActiveModel::Serializer
+  attributes :account_id
+
+  has_many :devices, serializer: REST::Keys::DeviceSerializer
+
+  def account_id
+    object.account.id.to_s
+  end
+end

app/services/activitypub/process_account_service.rb

@@ -76,6 +76,7 @@ class ActivityPub::ProcessAccountService < BaseService
     @account.shared_inbox_url        = (@json['endpoints'].is_a?(Hash) ? @json['endpoints']['sharedInbox'] : @json['sharedInbox']) || ''
     @account.followers_url           = @json['followers'] || ''
     @account.featured_collection_url = @json['featured'] || ''
+    @account.devices_url             = @json['devices'] || ''
     @account.url                     = url || @uri
     @account.uri                     = @uri
     @account.display_name            = @json['name'] || ''

app/services/backup_service.rb

@@ -22,7 +22,7 @@ class BackupService < BaseService
 
     account.statuses.with_includes.reorder(nil).find_in_batches do |statuses|
       statuses.each do |status|
-        item = serialize_payload(status, ActivityPub::ActivitySerializer, signer: @account)
+        item = serialize_payload(ActivityPub::ActivityPresenter.from_status(status), ActivityPub::ActivitySerializer, signer: @account)
         item.delete(:'@context')
 
         unless item[:type] == 'Announce' || item[:object][:attachment].blank?

app/services/deliver_to_device_service.rb

@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+class DeliverToDeviceService < BaseService
+  include Payloadable
+
+  class EncryptedMessage < ActiveModelSerializers::Model
+    attributes :source_account, :target_account, :source_device,
+               :target_device_id, :type, :body, :digest,
+               :message_franking
+  end
+
+  def call(source_account, source_device, options = {})
+    @source_account   = source_account
+    @source_device    = source_device
+    @target_account   = Account.find(options[:account_id])
+    @target_device_id = options[:device_id]
+    @body             = options[:body]
+    @type             = options[:type]
+    @hmac             = options[:hmac]
+
+    set_message_franking!
+
+    if @target_account.local?
+      deliver_to_local!
+    else
+      deliver_to_remote!
+    end
+  end
+
+  private
+
+  def set_message_franking!
+    @message_franking = message_franking.to_token
+  end
+
+  def deliver_to_local!
+    target_device = @target_account.devices.find_by!(device_id: @target_device_id)
+
+    target_device.encrypted_messages.create!(
+      from_account: @source_account,
+      from_device_id: @source_device.device_id,
+      type: @type,
+      body: @body,
+      digest: @hmac,
+      message_franking: @message_franking
+    )
+  end
+
+  def deliver_to_remote!
+    ActivityPub::DeliveryWorker.perform_async(
+      Oj.dump(serialize_payload(ActivityPub::ActivityPresenter.from_encrypted_message(encrypted_message), ActivityPub::ActivitySerializer)),
+      @source_account.id,
+      @target_account.inbox_url
+    )
+  end
+
+  def message_franking
+    MessageFranking.new(
+      source_account_id: @source_account.id,
+      target_account_id: @target_account.id,
+      hmac: @hmac,
+      timestamp: Time.now.utc
+    )
+  end
+
+  def encrypted_message
+    EncryptedMessage.new(
+      source_account: @source_account,
+      target_account: @target_account,
+      source_device: @source_device,
+      target_device_id: @target_device_id,
+      type: @type,
+      body: @body,
+      digest: @hmac,
+      message_franking: @message_franking
+    )
+  end
+end

app/services/keys/claim_service.rb

@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+class Keys::ClaimService < BaseService
+  HEADERS = { 'Content-Type' => 'application/activity+json' }.freeze
+
+  class Result < ActiveModelSerializers::Model
+    attributes :account, :device_id, :key_id,
+               :key, :signature
+
+    def initialize(account, device_id, key_attributes = {})
+      @account   = account
+      @device_id = device_id
+      @key_id    = key_attributes[:key_id]
+      @key       = key_attributes[:key]
+      @signature = key_attributes[:signature]
+    end
+  end
+
+  def call(source_account, target_account_id, device_id)
+    @source_account = source_account
+    @target_account = Account.find(target_account_id)
+    @device_id      = device_id
+
+    if @target_account.local?
+      claim_local_key!
+    else
+      claim_remote_key!
+    end
+  rescue ActiveRecord::RecordNotFound
+    nil
+  end
+
+  private
+
+  def claim_local_key!
+    device = @target_account.devices.find_by(device_id: @device_id)
+    key    = nil
+
+    ApplicationRecord.transaction do
+      key = device.one_time_keys.order(Arel.sql('random()')).first!
+      key.destroy!
+    end
+
+    @result = Result.new(@target_account, @device_id, key)
+  end
+
+  def claim_remote_key!
+    query_result = QueryService.new.call(@target_account)
+    device       = query_result.find(@device_id)
+
+    return unless device.present? && device.valid_claim_url?
+
+    json = fetch_resource_with_post(device.claim_url)
+
+    return unless json.present? && json['publicKeyBase64'].present?
+
+    @result = Result.new(@target_account, @device_id, key_id: json['id'], key: json['publicKeyBase64'], signature: json.dig('signature', 'signatureValue'))
+  rescue HTTP::Error, OpenSSL::SSL::SSLError, Mastodon::Error => e
+    Rails.logger.debug "Claiming one-time key for #{@target_account.acct}:#{@device_id} failed: #{e}"
+    nil
+  end
+
+  def fetch_resource_with_post(uri)
+    build_post_request(uri).perform do |response|
+      raise Mastodon::UnexpectedResponseError, response unless response_successful?(response) || response_error_unsalvageable?(response)
+
+      body_to_json(response.body_with_limit) if response.code == 200
+    end
+  end
+
+  def build_post_request(uri)
+    Request.new(:post, uri).tap do |request|
+      request.on_behalf_of(@source_account, :uri)
+      request.add_headers(HEADERS)
+    end
+  end
+end

app/services/keys/query_service.rb

@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+
+class Keys::QueryService < BaseService
+  include JsonLdHelper
+
+  class Result < ActiveModelSerializers::Model
+    attributes :account, :devices
+
+    def initialize(account, devices)
+      @account = account
+      @devices = devices || []
+    end
+
+    def find(device_id)
+      @devices.find { |device| device.device_id == device_id }
+    end
+  end
+
+  class Device < ActiveModelSerializers::Model
+    attributes :device_id, :name, :identity_key, :fingerprint_key
+
+    def initialize(attributes = {})
+      @device_id       = attributes[:device_id]
+      @name            = attributes[:name]
+      @identity_key    = attributes[:identity_key]
+      @fingerprint_key = attributes[:fingerprint_key]
+      @claim_url       = attributes[:claim_url]
+    end
+
+    def valid_claim_url?
+      return false if @claim_url.blank?
+
+      begin
+        parsed_url = Addressable::URI.parse(@claim_url).normalize
+      rescue Addressable::URI::InvalidURIError
+        return false
+      end
+
+      %w(http https).include?(parsed_url.scheme) && parsed_url.host.present?
+    end
+  end
+
+  def call(account)
+    @account = account
+
+    if @account.local?
+      query_local_devices!
+    else
+      query_remote_devices!
+    end
+
+    Result.new(@account, @devices)
+  end
+
+  private
+
+  def query_local_devices!
+    @devices = @account.devices.map { |device| Device.new(device) }
+  end
+
+  def query_remote_devices!
+    return if @account.devices_url.blank?
+
+    json = fetch_resource(@account.devices_url)
+
+    return if json['items'].blank?
+
+    @devices = json['items'].map do |device|
+      Device.new(device_id: device['id'], name: device['name'], identity_key: device.dig('identityKey', 'publicKeyBase64'), fingerprint_key: device.dig('fingerprintKey', 'publicKeyBase64'), claim_url: device['claim'])
+    end
+  rescue HTTP::Error, OpenSSL::SSL::SSLError, Mastodon::Error => e
+    Rails.logger.debug "Querying devices for #{@account.acct} failed: #{e}"
+    nil
+  end
+end

app/services/process_mentions_service.rb

@@ -65,7 +65,7 @@ class ProcessMentionsService < BaseService
 
   def activitypub_json
     return @activitypub_json if defined?(@activitypub_json)
-    @activitypub_json = Oj.dump(serialize_payload(@status, ActivityPub::ActivitySerializer, signer: @status.account))
+    @activitypub_json = Oj.dump(serialize_payload(ActivityPub::ActivityPresenter.from_status(@status), ActivityPub::ActivitySerializer, signer: @status.account))
   end
 
   def resolve_account_service

app/services/reblog_service.rb

@@ -60,6 +60,6 @@ class ReblogService < BaseService
   end
 
   def build_json(reblog)
-    Oj.dump(serialize_payload(reblog, ActivityPub::ActivitySerializer, signer: reblog.account))
+    Oj.dump(serialize_payload(ActivityPub::ActivityPresenter.from_status(reblog), ActivityPub::ActivitySerializer, signer: reblog.account))
   end
 end