Add E2EE API (#13820)

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