Add E2EE API (#13820)

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