diff --git a/lib/diaspora_federation/discovery/h_card.rb b/lib/diaspora_federation/discovery/h_card.rb
index 1bed928..17900fc 100644
--- a/lib/diaspora_federation/discovery/h_card.rb
+++ b/lib/diaspora_federation/discovery/h_card.rb
@@ -43,16 +43,16 @@ module DiasporaFederation
       # @!attribute [r] guid
       #   @see Entities::Person#guid
       #   @return [String] guid
-      property :guid
+      property :guid, :string
 
       # @!attribute [r] nickname
       #   The first part of the diaspora* ID
       #   @return [String] nickname
-      property :nickname, default: nil
+      property :nickname, :string, default: nil
 
       # @!attribute [r] full_name
       #   @return [String] display name of the user
-      property :full_name
+      property :full_name, :string
 
       # @!attribute [r] url
       #   @deprecated should be changed to the profile url. The pod url is in
@@ -60,7 +60,7 @@ module DiasporaFederation
       #     installations).
       #
       #   @return [String] link to the pod
-      property :url, default: nil
+      property :url, :string, default: nil
 
       # @!attribute [r] public_key
       #   When a user is created on the pod, the pod MUST generate a pgp keypair
@@ -69,17 +69,17 @@ module DiasporaFederation
       #   "-----BEGIN PUBLIC KEY-----" and ending with "-----END PUBLIC KEY-----".
       #
       #   @return [String] public key
-      property :public_key
+      property :public_key, :string
 
       # @!attribute [r] photo_large_url
       #   @return [String] url to the big avatar (300x300)
-      property :photo_large_url
+      property :photo_large_url, :string
       # @!attribute [r] photo_medium_url
       #   @return [String] url to the medium avatar (100x100)
-      property :photo_medium_url
+      property :photo_medium_url, :string
       # @!attribute [r] photo_small_url
       #   @return [String] url to the small avatar (50x50)
-      property :photo_small_url
+      property :photo_small_url, :string
 
       # @!attribute [r] first_name
       #   @deprecated We decided to only use one name field, these should be removed
@@ -87,7 +87,7 @@ module DiasporaFederation
       #
       #   @see #full_name
       #   @return [String] first name
-      property :first_name
+      property :first_name, :string
 
       # @!attribute [r] last_name
       #   @deprecated We decided to only use one name field, these should be removed
@@ -95,7 +95,7 @@ module DiasporaFederation
       #
       #   @see #full_name
       #   @return [String] last name
-      property :last_name
+      property :last_name, :string
 
       # @!attribute [r] searchable
       #   @deprecated As this is a simple property, consider move to WebFinger instead
@@ -105,7 +105,7 @@ module DiasporaFederation
       #
       #   flag if a user is searchable by name
       #   @return [Boolean] searchable flag
-      property :searchable
+      property :searchable, :boolean
 
       # CSS selectors for finding all the hCard fields
       SELECTORS = {
diff --git a/lib/diaspora_federation/discovery/web_finger.rb b/lib/diaspora_federation/discovery/web_finger.rb
index 4d2da11..5c9444b 100644
--- a/lib/diaspora_federation/discovery/web_finger.rb
+++ b/lib/diaspora_federation/discovery/web_finger.rb
@@ -35,24 +35,24 @@ module DiasporaFederation
       #   The Subject element should contain the webfinger address that was asked
       #   for. If it does not, then this webfinger profile MUST be ignored.
       #   @return [String]
-      property :acct_uri
+      property :acct_uri, :string
 
       # @!attribute [r] alias_url
       #   @note could be nil
       #   @return [String] link to the users profile
-      property :alias_url
+      property :alias_url, :string
 
       # @!attribute [r] hcard_url
       #   @return [String] link to the +hCard+
-      property :hcard_url
+      property :hcard_url, :string
 
       # @!attribute [r] seed_url
       #   @return [String] link to the pod
-      property :seed_url
+      property :seed_url, :string
 
       # @!attribute [r] profile_url
       #   @return [String] link to the users profile
-      property :profile_url
+      property :profile_url, :string
 
       # @!attribute [r] atom_url
       #   This atom feed is an Activity Stream of the user's public posts. diaspora*
@@ -63,18 +63,18 @@ module DiasporaFederation
       #   Note that this feed MAY also be made available through the PubSubHubbub
       #   mechanism by supplying a <link rel="hub"> in the atom feed itself.
       #   @return [String] atom feed url
-      property :atom_url
+      property :atom_url, :string
 
       # @!attribute [r] salmon_url
       #   @note could be nil
       #   @return [String] salmon endpoint url
       #   @see https://cdn.rawgit.com/salmon-protocol/salmon-protocol/master/draft-panzer-salmon-00.html#SMLR
       #     Panzer draft for Salmon, paragraph 3.3
-      property :salmon_url
+      property :salmon_url, :string
 
       # @!attribute [r] subscribe_url
       #   This url is used to find another user on the home-pod of the user in the webfinger.
-      property :subscribe_url
+      property :subscribe_url, :string
 
       # @!attribute [r] guid
       #   @deprecated Either convert these to +Property+ elements or move to the
@@ -84,7 +84,7 @@ module DiasporaFederation
       #   @see HCard#guid
       #   @see Entities::Person#guid
       #   @return [String] guid
-      property :guid
+      property :guid, :string
 
       # @!attribute [r] public_key
       #   @deprecated Either convert these to +Property+ elements or move to the
@@ -98,7 +98,7 @@ module DiasporaFederation
       #   DER-encoded PKCS#1 key beginning with the text
       #   "-----BEGIN PUBLIC KEY-----" and ending with "-----END PUBLIC KEY-----".
       #   @return [String] public key
-      property :public_key
+      property :public_key, :string
 
       # +hcard_url+ link relation
       REL_HCARD = "http://microformats.org/profile/hcard".freeze
diff --git a/lib/diaspora_federation/entities/account_deletion.rb b/lib/diaspora_federation/entities/account_deletion.rb
index 7c4553c..88e087e 100644
--- a/lib/diaspora_federation/entities/account_deletion.rb
+++ b/lib/diaspora_federation/entities/account_deletion.rb
@@ -12,7 +12,7 @@ module DiasporaFederation
       #   Alias for author
       #   @see AccountDeletion#author
       #   @return [String] diaspora* ID
-      property :author, alias: :diaspora_id, xml_name: :diaspora_handle
+      property :author, :string, alias: :diaspora_id, xml_name: :diaspora_handle
 
       # @return [String] string representation of this object
       def to_s
diff --git a/lib/diaspora_federation/entities/comment.rb b/lib/diaspora_federation/entities/comment.rb
index 561938b..99c8319 100644
--- a/lib/diaspora_federation/entities/comment.rb
+++ b/lib/diaspora_federation/entities/comment.rb
@@ -15,12 +15,12 @@ module DiasporaFederation
 
       # @!attribute [r] text
       #   @return [String] the comment text
-      property :text
+      property :text, :string
 
       # @!attribute [r] created_at
       #   Comment entity creation time
       #   @return [Time] creation time
-      property :created_at, default: -> { Time.now.utc }
+      property :created_at, :timestamp, default: -> { Time.now.utc }
     end
   end
 end
diff --git a/lib/diaspora_federation/entities/contact.rb b/lib/diaspora_federation/entities/contact.rb
index 02451f9..693895d 100644
--- a/lib/diaspora_federation/entities/contact.rb
+++ b/lib/diaspora_federation/entities/contact.rb
@@ -9,21 +9,21 @@ module DiasporaFederation
       #   The diaspora* ID of the person who shares their profile
       #   @see Person#author
       #   @return [String] sender ID
-      property :author
+      property :author, :string
 
       # @!attribute [r] recipient
       #   The diaspora* ID of the person who will be shared with
       #   @see Validation::Rule::DiasporaId
       #   @return [String] recipient ID
-      property :recipient
+      property :recipient, :string
 
       # @!attribute [r] following
       #   @return [Boolean] if the author is following the person
-      property :following, default: true
+      property :following, :boolean, default: true
 
       # @!attribute [r] sharing
       #   @return [Boolean] if the author is sharing with the person
-      property :sharing, default: true
+      property :sharing, :boolean, default: true
 
       # @return [String] string representation of this object
       def to_s
diff --git a/lib/diaspora_federation/entities/conversation.rb b/lib/diaspora_federation/entities/conversation.rb
index 6726dfd..57898d0 100644
--- a/lib/diaspora_federation/entities/conversation.rb
+++ b/lib/diaspora_federation/entities/conversation.rb
@@ -8,26 +8,26 @@ module DiasporaFederation
       #   The diaspora* ID of the person initiated the conversation
       #   @see Person#author
       #   @return [String] diaspora* ID
-      property :author, xml_name: :diaspora_handle
+      property :author, :string, xml_name: :diaspora_handle
 
       # @!attribute [r] guid
       #   A random string of at least 16 chars
       #   @see Validation::Rule::Guid
       #   @return [String] conversation guid
-      property :guid
+      property :guid, :string
 
       # @!attribute [r] subject
       #   @return [String] the conversation subject
-      property :subject
+      property :subject, :string
 
       # @!attribute [r] created_at
       #   @return [Time] Conversation creation time
-      property :created_at, default: -> { Time.now.utc }
+      property :created_at, :timestamp, default: -> { Time.now.utc }
 
       # @!attribute [r] participants
       #   The diaspora* IDs of the persons participating the conversation separated by ";"
       #   @return [String] participants diaspora* IDs
-      property :participants, xml_name: :participant_handles
+      property :participants, :string, xml_name: :participant_handles
 
       # @!attribute [r] messages
       #   @return [[Entities::Message]] Messages of this conversation
diff --git a/lib/diaspora_federation/entities/like.rb b/lib/diaspora_federation/entities/like.rb
index ea182fb..02324ca 100644
--- a/lib/diaspora_federation/entities/like.rb
+++ b/lib/diaspora_federation/entities/like.rb
@@ -14,14 +14,14 @@ module DiasporaFederation
       #   If +true+ set a like, if +false+, set a dislike (dislikes are currently not
       #   implemented in the diaspora* frontend).
       #   @return [Boolean] is it a like or a dislike
-      property :positive
+      property :positive, :boolean
 
       # @!attribute [r] parent_type
       #   A string describing the type of the parent
       #   Can be "Post" or "Comment" (Comments are currently not implemented in the
       #   diaspora* frontend).
       #   @return [String] parent type
-      property :parent_type, xml_name: :target_type
+      property :parent_type, :string, xml_name: :target_type
     end
   end
 end
diff --git a/lib/diaspora_federation/entities/location.rb b/lib/diaspora_federation/entities/location.rb
index 25aaf84..5bd8501 100644
--- a/lib/diaspora_federation/entities/location.rb
+++ b/lib/diaspora_federation/entities/location.rb
@@ -7,17 +7,17 @@ module DiasporaFederation
       # @!attribute [r] address
       #   A string describing your location, e.g. a city name, a street name, etc
       #   @return [String] address
-      property :address
+      property :address, :string
 
       # @!attribute [r] lat
       #   Geographical latitude of your location
       #   @return [String] latitude
-      property :lat
+      property :lat, :string
 
       # @!attribute [r] lng
       #   Geographical longitude of your location
       #   @return [String] longitude
-      property :lng
+      property :lng, :string
     end
   end
 end
diff --git a/lib/diaspora_federation/entities/message.rb b/lib/diaspora_federation/entities/message.rb
index 281f200..018c5ca 100644
--- a/lib/diaspora_federation/entities/message.rb
+++ b/lib/diaspora_federation/entities/message.rb
@@ -13,18 +13,18 @@ module DiasporaFederation
       # @!attribute [r] text
       #   Text of the message composed by a user
       #   @return [String] text
-      property :text
+      property :text, :string
 
       # @!attribute [r] created_at
       #   Message creation time
       #   @return [Time] creation time
-      property :created_at, default: -> { Time.now.utc }
+      property :created_at, :timestamp, default: -> { Time.now.utc }
 
       # @!attribute [r] conversation_guid
       #   Guid of a conversation this message belongs to
       #   @see Conversation#guid
       #   @return [String] conversation guid
-      property :conversation_guid
+      property :conversation_guid, :string
 
       # It is only valid to receive a {Message} from the author itself,
       # or from the author of the parent {Conversation} if the author signature is valid.
@@ -48,6 +48,16 @@ module DiasporaFederation
         parent.author
       end
 
+      # old timestamp format, because this signature is only used from old pods which also relay with old format
+      # @deprecated remove after {Message} doesn't include {Relayable} anymore
+      def normalize_property(name, value)
+        if name == :created_at
+          value.to_s
+        else
+          super
+        end
+      end
+
       # Default implementation, don't verify signatures for a {Message}.
       # @see Entity.populate_entity
       # @deprecated remove after {Message} doesn't include {Relayable} anymore
diff --git a/lib/diaspora_federation/entities/participation.rb b/lib/diaspora_federation/entities/participation.rb
index 63fdaae..075e05d 100644
--- a/lib/diaspora_federation/entities/participation.rb
+++ b/lib/diaspora_federation/entities/participation.rb
@@ -14,7 +14,7 @@ module DiasporaFederation
       #   A string describing a type of the target to subscribe on
       #   Currently only "Post" is supported.
       #   @return [String] parent type
-      property :parent_type, xml_name: :target_type
+      property :parent_type, :string, xml_name: :target_type
 
       # It is only valid to receive a {Participation} from the author themself.
       # @deprecated remove after {Participation} doesn't include {Relayable} anymore
diff --git a/lib/diaspora_federation/entities/person.rb b/lib/diaspora_federation/entities/person.rb
index 44868d7..ab48857 100644
--- a/lib/diaspora_federation/entities/person.rb
+++ b/lib/diaspora_federation/entities/person.rb
@@ -9,7 +9,7 @@ module DiasporaFederation
       #   MUST assign them a guid - a random string of at least 16 chars.
       #   @see Validation::Rule::Guid
       #   @return [String] guid
-      property :guid
+      property :guid, :string
 
       # @!attribute [r] author
       #   The diaspora* ID of the person
@@ -19,12 +19,12 @@ module DiasporaFederation
       #   alias for author
       #   @see Person#author
       #   @return [String] diaspora* ID
-      property :author, alias: :diaspora_id, xml_name: :diaspora_handle
+      property :author, :string, alias: :diaspora_id, xml_name: :diaspora_handle
 
       # @!attribute [r] url
       #   @see Discovery::WebFinger#seed_url
       #   @return [String] link to the pod
-      property :url
+      property :url, :string
 
       # @!attribute [r] profile
       #   All profile data of the person
@@ -34,7 +34,7 @@ module DiasporaFederation
       # @!attribute [r] exported_key
       #   @see Discovery::HCard#public_key
       #   @return [String] public key
-      property :exported_key
+      property :exported_key, :string
     end
   end
 end
diff --git a/lib/diaspora_federation/entities/photo.rb b/lib/diaspora_federation/entities/photo.rb
index 83e5585..5ed71ea 100644
--- a/lib/diaspora_federation/entities/photo.rb
+++ b/lib/diaspora_federation/entities/photo.rb
@@ -8,52 +8,52 @@ module DiasporaFederation
       #   A random string of at least 16 chars
       #   @see Validation::Rule::Guid
       #   @return [String] guid
-      property :guid
+      property :guid, :string
 
       # @!attribute [r] author
       #   The diaspora* ID of the person who uploaded the photo
       #   @see Person#author
       #   @return [String] author diaspora* ID
-      property :author, xml_name: :diaspora_handle
+      property :author, :string, xml_name: :diaspora_handle
 
       # @!attribute [r] public
       #   Points if the photo is visible to everyone or only to some aspects
       #   @return [Boolean] is it public
-      property :public, default: false
+      property :public, :boolean, default: false
 
       # @!attribute [r] created_at
       #   Photo entity creation time
       #   @return [Time] creation time
-      property :created_at, default: -> { Time.now.utc }
+      property :created_at, :timestamp, default: -> { Time.now.utc }
 
       # @!attribute [r] remote_photo_path
       #   An url of the photo on a remote server
       #   @return [String] remote photo url
-      property :remote_photo_path
+      property :remote_photo_path, :string
 
       # @!attribute [r] remote_photo_name
       #   @return [String] remote photo name
-      property :remote_photo_name
+      property :remote_photo_name, :string
 
       # @!attribute [r] text
       #   @return [String] text
-      property :text, default: nil
+      property :text, :string, default: nil
 
       # @!attribute [r] status_message_guid
       #   Guid of a status message this photo belongs to
       #   @see StatusMessage#guid
       #   @return [String] guid
-      property :status_message_guid, default: nil
+      property :status_message_guid, :string, default: nil
 
       # @!attribute [r] height
       #   Photo height
-      #   @return [String] height
-      property :height
+      #   @return [Integer] height
+      property :height, :integer
 
       # @!attribute [r] width
       #   Photo width
-      #   @return [String] width
-      property :width
+      #   @return [Integer] width
+      property :width, :integer
     end
   end
 end
diff --git a/lib/diaspora_federation/entities/poll.rb b/lib/diaspora_federation/entities/poll.rb
index 4eeb916..47fd2dc 100644
--- a/lib/diaspora_federation/entities/poll.rb
+++ b/lib/diaspora_federation/entities/poll.rb
@@ -8,12 +8,12 @@ module DiasporaFederation
       #   A random string of at least 16 chars
       #   @see Validation::Rule::Guid
       #   @return [String] poll guid
-      property :guid
+      property :guid, :string
 
       # @!attribute [r] question
       #   Text of the question posed by a user
       #   @return [String] question
-      property :question
+      property :question, :string
 
       # @!attribute [r] poll_answers
       #   Array of possible answers for the poll
diff --git a/lib/diaspora_federation/entities/poll_answer.rb b/lib/diaspora_federation/entities/poll_answer.rb
index 85ab83f..7c1ee17 100644
--- a/lib/diaspora_federation/entities/poll_answer.rb
+++ b/lib/diaspora_federation/entities/poll_answer.rb
@@ -8,12 +8,12 @@ module DiasporaFederation
       #   A random string of at least 16 chars
       #   @see Validation::Rule::Guid
       #   @return [String] guid
-      property :guid
+      property :guid, :string
 
       # @!attribute [r] answer
       #   Text of the answer
       #   @return [String] answer
-      property :answer
+      property :answer, :string
     end
   end
 end
diff --git a/lib/diaspora_federation/entities/poll_participation.rb b/lib/diaspora_federation/entities/poll_participation.rb
index 24418a1..8ef8f9e 100644
--- a/lib/diaspora_federation/entities/poll_participation.rb
+++ b/lib/diaspora_federation/entities/poll_participation.rb
@@ -17,7 +17,7 @@ module DiasporaFederation
       #   Guid of the answer selected by the user
       #   @see PollAnswer#guid
       #   @return [String] poll answer guid
-      property :poll_answer_guid
+      property :poll_answer_guid, :string
     end
   end
 end
diff --git a/lib/diaspora_federation/entities/post.rb b/lib/diaspora_federation/entities/post.rb
index 5ef961c..af161a1 100644
--- a/lib/diaspora_federation/entities/post.rb
+++ b/lib/diaspora_federation/entities/post.rb
@@ -26,10 +26,10 @@ module DiasporaFederation
       # @param [Entity] entity the entity in which it is included
       def self.included(entity)
         entity.class_eval do
-          property :author, xml_name: :diaspora_handle
-          property :guid
-          property :created_at, default: -> { Time.now.utc }
-          property :provider_display_name, default: nil
+          property :author, :string, xml_name: :diaspora_handle
+          property :guid, :string
+          property :created_at, :timestamp, default: -> { Time.now.utc }
+          property :provider_display_name, :string, default: nil
         end
       end
     end
diff --git a/lib/diaspora_federation/entities/profile.rb b/lib/diaspora_federation/entities/profile.rb
index a61bbde..7a9b4c6 100644
--- a/lib/diaspora_federation/entities/profile.rb
+++ b/lib/diaspora_federation/entities/profile.rb
@@ -12,7 +12,7 @@ module DiasporaFederation
       #   Alias for author
       #   @see Profile#author
       #   @return [String] diaspora* ID
-      property :author, alias: :diaspora_id, xml_name: :diaspora_handle
+      property :author, :string, alias: :diaspora_id, xml_name: :diaspora_handle
 
       # @!attribute [r] first_name
       #   @deprecated We decided to only use one name field, these should be removed
@@ -20,7 +20,7 @@ module DiasporaFederation
       #   @see #full_name
       #   @see Discovery::HCard#first_name
       #   @return [String] first name
-      property :first_name, default: nil
+      property :first_name, :string, default: nil
 
       # @!attribute [r] last_name
       #   @deprecated We decided to only use one name field, these should be removed
@@ -28,33 +28,33 @@ module DiasporaFederation
       #   @see #full_name
       #   @see Discovery::HCard#last_name
       #   @return [String] last name
-      property :last_name, default: nil
+      property :last_name, :string, default: nil
 
       # @!attribute [r] image_url
       #   @see Discovery::HCard#photo_large_url
       #   @return [String] url to the big avatar (300x300)
-      property :image_url, default: nil
+      property :image_url, :string, default: nil
       # @!attribute [r] image_url_medium
       #   @see Discovery::HCard#photo_medium_url
       #   @return [String] url to the medium avatar (100x100)
-      property :image_url_medium, default: nil
+      property :image_url_medium, :string, default: nil
       # @!attribute [r] image_url_small
       #   @see Discovery::HCard#photo_small_url
       #   @return [String] url to the small avatar (50x50)
-      property :image_url_small, default: nil
+      property :image_url_small, :string, default: nil
 
-      property :birthday, default: nil
-      property :gender, default: nil
-      property :bio, default: nil
-      property :location, default: nil
+      property :birthday, :string, default: nil
+      property :gender, :string, default: nil
+      property :bio, :string, default: nil
+      property :location, :string, default: nil
 
       # @!attribute [r] searchable
       #   @see Discovery::HCard#searchable
       #   @return [Boolean] searchable flag
-      property :searchable, default: true
+      property :searchable, :boolean, default: true
 
-      property :nsfw, default: false
-      property :tag_string, default: nil
+      property :nsfw, :boolean, default: false
+      property :tag_string, :string, default: nil
 
       # @return [String] string representation of this object
       def to_s
diff --git a/lib/diaspora_federation/entities/related_entity.rb b/lib/diaspora_federation/entities/related_entity.rb
index 6f8cf9f..850babe 100644
--- a/lib/diaspora_federation/entities/related_entity.rb
+++ b/lib/diaspora_federation/entities/related_entity.rb
@@ -7,17 +7,17 @@ module DiasporaFederation
       #   The diaspora* ID of the author
       #   @see Person#author
       #   @return [String] diaspora* ID
-      property :author
+      property :author, :string
 
       # @!attribute [r] local
       #   +true+ if the owner of the entity is local on the pod
       #   @return [Boolean] is it a like or a dislike
-      property :local
+      property :local, :boolean
 
       # @!attribute [r] public
       #   Shows whether the entity is visible to everyone or only to some aspects
       #   @return [Boolean] is it public
-      property :public, default: false
+      property :public, :boolean, default: false
 
       # @!attribute [r] parent
       #   Parent if the entity also has a parent (Comment or Like) or +nil+ if it has no parent
diff --git a/lib/diaspora_federation/entities/relayable.rb b/lib/diaspora_federation/entities/relayable.rb
index 1cc3d77..cf0a2ad 100644
--- a/lib/diaspora_federation/entities/relayable.rb
+++ b/lib/diaspora_federation/entities/relayable.rb
@@ -54,11 +54,11 @@ module DiasporaFederation
       # @param [Entity] klass the entity in which it is included
       def self.included(klass)
         klass.class_eval do
-          property :author, xml_name: :diaspora_handle
-          property :guid
-          property :parent_guid
-          property :author_signature, default: nil
-          property :parent_author_signature, default: nil
+          property :author, :string, xml_name: :diaspora_handle
+          property :guid, :string
+          property :parent_guid, :string
+          property :author_signature, :string, default: nil
+          property :parent_author_signature, :string, default: nil
           entity :parent, Entities::RelatedEntity
         end
 
diff --git a/lib/diaspora_federation/entities/relayable_retraction.rb b/lib/diaspora_federation/entities/relayable_retraction.rb
index 8d742ad..00f0768 100644
--- a/lib/diaspora_federation/entities/relayable_retraction.rb
+++ b/lib/diaspora_federation/entities/relayable_retraction.rb
@@ -24,25 +24,25 @@ module DiasporaFederation
       #   This signature is mandatory only when federating from an upstream author to the subscribers.
       #   @see Relayable#parent_author_signature
       #   @return [String] parent author signature
-      property :parent_author_signature, default: nil
+      property :parent_author_signature, :string, default: nil
 
       # @!attribute [r] target_guid
       #   Guid of a relayable to be deleted
       #   @see Comment#guid
       #   @return [String] target guid
-      property :target_guid
+      property :target_guid, :string
 
       # @!attribute [r] target_type
       #   A string describing a type of the target
       #   @see Retraction#target_type
       #   @return [String] target type
-      property :target_type
+      property :target_type, :string
 
       # @!attribute [r] author
       #   The diaspora* ID of the person who deletes a relayable
       #   @see Person#author
       #   @return [String] diaspora* ID
-      property :author, xml_name: :sender_handle
+      property :author, :string, xml_name: :sender_handle
 
       # @!attribute [r] target_author_signature
       #   Contains a signature of the entity using the private key of the
@@ -51,7 +51,7 @@ module DiasporaFederation
       #   author is done.
       #   @see Relayable#author_signature
       #   @return [String] target author signature
-      property :target_author_signature, default: nil
+      property :target_author_signature, :string, default: nil
 
       # @!attribute [r] target
       #   Target entity
diff --git a/lib/diaspora_federation/entities/request.rb b/lib/diaspora_federation/entities/request.rb
index 096cc70..7290974 100644
--- a/lib/diaspora_federation/entities/request.rb
+++ b/lib/diaspora_federation/entities/request.rb
@@ -10,13 +10,13 @@ module DiasporaFederation
       #   The diaspora* ID of the person who share their profile
       #   @see Person#author
       #   @return [String] sender ID
-      property :author, xml_name: :sender_handle
+      property :author, :string, xml_name: :sender_handle
 
       # @!attribute [r] recipient
       #   The diaspora* ID of the person who will be shared with
       #   @see Validation::Rule::DiasporaId
       #   @return [String] recipient ID
-      property :recipient, xml_name: :recipient_handle
+      property :recipient, :string, xml_name: :recipient_handle
 
       # Use only {Contact} for receive
       # @return [Contact] instance as contact
diff --git a/lib/diaspora_federation/entities/reshare.rb b/lib/diaspora_federation/entities/reshare.rb
index 95f27d7..cd831d7 100644
--- a/lib/diaspora_federation/entities/reshare.rb
+++ b/lib/diaspora_federation/entities/reshare.rb
@@ -10,18 +10,18 @@ module DiasporaFederation
       #   The diaspora* ID of the person who posted the original post
       #   @see Person#author
       #   @return [String] diaspora* ID
-      property :root_author, xml_name: :root_diaspora_id
+      property :root_author, :string, xml_name: :root_diaspora_id
 
       # @!attribute [r] root_guid
       #   Guid of the original post
       #   @see StatusMessage#guid
       #   @return [String] root guid
-      property :root_guid
+      property :root_guid, :string
 
       # @!attribute [r] public
       #   Has no meaning at the moment
       #   @return [Boolean] public
-      property :public, default: true # always true? (we only reshare public posts)
+      property :public, :boolean, default: true # always true? (we only reshare public posts)
 
       # @return [String] string representation of this object
       def to_s
diff --git a/lib/diaspora_federation/entities/retraction.rb b/lib/diaspora_federation/entities/retraction.rb
index c3db746..cf1df09 100644
--- a/lib/diaspora_federation/entities/retraction.rb
+++ b/lib/diaspora_federation/entities/retraction.rb
@@ -8,17 +8,17 @@ module DiasporaFederation
       #   The diaspora* ID of the person who deletes the entity
       #   @see Person#author
       #   @return [String] diaspora* ID
-      property :author, xml_name: :diaspora_handle
+      property :author, :string, xml_name: :diaspora_handle
 
       # @!attribute [r] target_guid
       #   Guid of the entity to be deleted
       #   @return [String] target guid
-      property :target_guid, xml_name: :post_guid
+      property :target_guid, :string, xml_name: :post_guid
 
       # @!attribute [r] target_type
       #   A string describing the type of the target
       #   @return [String] target type
-      property :target_type, xml_name: :type
+      property :target_type, :string, xml_name: :type
 
       # @!attribute [r] target
       #   Target entity
diff --git a/lib/diaspora_federation/entities/signed_retraction.rb b/lib/diaspora_federation/entities/signed_retraction.rb
index 9df148a..ed88dbd 100644
--- a/lib/diaspora_federation/entities/signed_retraction.rb
+++ b/lib/diaspora_federation/entities/signed_retraction.rb
@@ -10,25 +10,25 @@ module DiasporaFederation
       #   Guid of a post to be deleted
       #   @see Retraction#target_guid
       #   @return [String] target guid
-      property :target_guid
+      property :target_guid, :string
 
       # @!attribute [r] target_type
       #   A string describing the type of the target
       #   @see Retraction#target_type
       #   @return [String] target type
-      property :target_type
+      property :target_type, :string
 
       # @!attribute [r] author
       #   The diaspora* ID of the person who deletes a post
       #   @see Person#author
       #   @return [String] diaspora* ID
-      property :author, xml_name: :sender_handle
+      property :author, :string, xml_name: :sender_handle
 
       # @!attribute [r] author_signature
       #   Contains a signature of the entity using the private key of the author of a post
       #   This signature is mandatory.
       #   @return [String] author signature
-      property :target_author_signature, default: nil
+      property :target_author_signature, :string, default: nil
 
       # @!attribute [r] target
       #   Target entity
diff --git a/lib/diaspora_federation/entities/status_message.rb b/lib/diaspora_federation/entities/status_message.rb
index 14fbc79..555b8b5 100644
--- a/lib/diaspora_federation/entities/status_message.rb
+++ b/lib/diaspora_federation/entities/status_message.rb
@@ -9,7 +9,7 @@ module DiasporaFederation
       # @!attribute [r] text
       #   Text of the status message composed by the user
       #   @return [String] text of the status message
-      property :text, xml_name: :raw_message
+      property :text, :string, xml_name: :raw_message
 
       # @!attribute [r] photos
       #   Optional photos attached to the status message
@@ -29,7 +29,7 @@ module DiasporaFederation
       # @!attribute [r] public
       #   Shows whether the status message is visible to everyone or only to some aspects
       #   @return [Boolean] is it public
-      property :public, default: false
+      property :public, :boolean, default: false
 
       private
 
diff --git a/lib/diaspora_federation/entity.rb b/lib/diaspora_federation/entity.rb
index 5bbb64d..ccaa860 100644
--- a/lib/diaspora_federation/entity.rb
+++ b/lib/diaspora_federation/entity.rb
@@ -76,7 +76,7 @@ module DiasporaFederation
       properties.map {|key, value|
         type = self.class.class_props[key]
 
-        if type == String || value.nil?
+        if type.instance_of?(Symbol) || value.nil?
           [key, value]
         elsif type.instance_of?(Class)
           [key, value.to_h]
@@ -160,11 +160,15 @@ module DiasporaFederation
       type = self.class.class_props[name]
       return false if type.nil? # property undefined
 
-      setable_string?(type, val) || setable_nested?(type, val) || setable_multi?(type, val)
+      setable_property?(type, val) || setable_nested?(type, val) || setable_multi?(type, val)
+    end
+
+    def setable_property?(type, val)
+      setable_string?(type, val) || type == :timestamp && val.is_a?(Time)
     end
 
     def setable_string?(type, val)
-      type == String && val.respond_to?(:to_s)
+      %i(string integer boolean).include?(type) && val.respond_to?(:to_s)
     end
 
     def setable_nested?(type, val)
@@ -216,7 +220,18 @@ module DiasporaFederation
     end
 
     def normalized_properties
-      properties.map {|name, value| [name, self.class.class_props[name] == String ? value.to_s : value] }.to_h
+      properties.map {|name, value| [name, normalize_property(name, value)] }.to_h
+    end
+
+    def normalize_property(name, value)
+      case self.class.class_props[name]
+      when :string, :integer, :boolean
+        value.to_s
+      when :timestamp
+        value.nil? ? "" : value.utc.iso8601
+      else
+        value
+      end
     end
 
     # default: nothing to enrich
@@ -265,12 +280,12 @@ module DiasporaFederation
     end
 
     # @param [String] name property name to parse
-    # @param [Class] type target type to parse
+    # @param [Class, Symbol] type target type to parse
     # @param [Nokogiri::XML::Element] root_node XML node to parse
     # @return [Object] parsed data
     private_class_method def self.parse_element_from_node(name, type, root_node)
-      if type == String
-        parse_string_from_node(name, root_node)
+      if type.instance_of?(Symbol)
+        parse_string_from_node(name, type, root_node)
       elsif type.instance_of?(Array)
         parse_array_from_node(type.first, root_node)
       elsif type.ancestors.include?(Entity)
@@ -281,12 +296,34 @@ module DiasporaFederation
     # Create simple entry in data hash
     #
     # @param [String] name xml tag to parse
+    # @param [Class, Symbol] type target type to parse
     # @param [Nokogiri::XML::Element] root_node XML root_node to parse
     # @return [String] data
-    private_class_method def self.parse_string_from_node(name, root_node)
+    private_class_method def self.parse_string_from_node(name, type, root_node)
       node = root_node.xpath(name.to_s)
       node = root_node.xpath(xml_names[name].to_s) if node.empty?
-      node.first.text if node.any?
+      parse_property(type, node.first.text) if node.any?
+    end
+
+    # @param [Symbol] type target type to parse
+    # @param [String] text data as string
+    # @return [String, Boolean, Integer, Time] data
+    private_class_method def self.parse_property(type, text)
+      case type
+      when :timestamp
+        begin
+          Time.parse(text).utc
+        rescue
+          nil
+        end
+      when :integer
+        text.to_i if text =~ /^\d+$/
+      when :boolean
+        return true if text =~ /(true|t|yes|y|1)$/i
+        false if text =~ /(false|f|no|n|0)$/i
+      else
+        text
+      end
     end
 
     # Create an entry in the data hash for the nested entity
diff --git a/lib/diaspora_federation/properties_dsl.rb b/lib/diaspora_federation/properties_dsl.rb
index 24d28b5..9fa3302 100644
--- a/lib/diaspora_federation/properties_dsl.rb
+++ b/lib/diaspora_federation/properties_dsl.rb
@@ -18,12 +18,15 @@ module DiasporaFederation
 
     # Define a generic (string-type) property
     # @param [Symbol] name property name
+    # @param [Symbol] type property type
     # @param [Hash] opts further options
     # @option opts [Object, #call] :default a default value, making the
     #   property optional
     # @option opts [Symbol] :xml_name another name used for xml generation
-    def property(name, opts={})
-      define_property name, String, opts
+    def property(name, type, opts={})
+      raise InvalidType unless property_type_valid?(type)
+
+      define_property name, type, opts
     end
 
     # Define a property that should contain another Entity or an array of
@@ -35,7 +38,7 @@ module DiasporaFederation
     # @option opts [Object, #call] :default a default value, making the
     #   property optional
     def entity(name, type, opts={})
-      raise InvalidType unless type_valid?(type)
+      raise InvalidType unless entity_type_valid?(type)
 
       define_property name, type, opts
     end
@@ -86,9 +89,11 @@ module DiasporaFederation
 
     # @deprecated
     def determine_xml_name(name, type, opts={})
-      raise ArgumentError, "xml_name is not supported for nested entities" if type != String && opts.has_key?(:xml_name)
+      if !type.instance_of?(Symbol) && opts.has_key?(:xml_name)
+        raise ArgumentError, "xml_name is not supported for nested entities"
+      end
 
-      if type == String
+      if type.instance_of?(Symbol)
         if opts.has_key? :xml_name
           raise InvalidName, "invalid xml_name" unless name_valid?(opts[:xml_name])
           opts[:xml_name]
@@ -121,10 +126,14 @@ module DiasporaFederation
       name.instance_of?(Symbol)
     end
 
+    def property_type_valid?(type)
+      %i(string integer boolean timestamp).include?(type)
+    end
+
     # Checks if the type extends {Entity}
     # @param [Class] type the type to check
     # @return [Boolean]
-    def type_valid?(type)
+    def entity_type_valid?(type)
       [type].flatten.all? {|type|
         type.respond_to?(:ancestors) && type.ancestors.include?(Entity)
       }
diff --git a/spec/entities.rb b/spec/entities.rb
index 5747df1..18f743e 100644
--- a/spec/entities.rb
+++ b/spec/entities.rb
@@ -1,38 +1,38 @@
 module DiasporaFederation
   module Entities
     class TestEntity < DiasporaFederation::Entity
-      property :test
+      property :test, :string
     end
 
     class TestDefaultEntity < DiasporaFederation::Entity
-      property :test1
-      property :test2
-      property :test3, default: true
-      property :test4, default: -> { true }
+      property :test1, :string
+      property :test2, :string
+      property :test3, :boolean, default: true
+      property :test4, :boolean, default: -> { true }
     end
 
     class OtherEntity < DiasporaFederation::Entity
-      property :asdf
+      property :asdf, :string
     end
 
     class TestNestedEntity < DiasporaFederation::Entity
-      property :asdf
+      property :asdf, :string
       entity :test, TestEntity, default: nil
       entity :multi, [OtherEntity]
     end
 
     class TestEntityWithXmlName < DiasporaFederation::Entity
-      property :test
-      property :qwer, xml_name: :asdf
+      property :test, :string
+      property :qwer, :string, xml_name: :asdf
     end
 
     class TestEntityWithRelatedEntity < DiasporaFederation::Entity
-      property :test
+      property :test, :string
       entity :parent, RelatedEntity
     end
 
     class Entity < DiasporaFederation::Entity
-      property :test
+      property :test, :string
     end
   end
 
diff --git a/spec/lib/diaspora_federation/entities/comment_spec.rb b/spec/lib/diaspora_federation/entities/comment_spec.rb
index 1e630c0..25ef0d9 100644
--- a/spec/lib/diaspora_federation/entities/comment_spec.rb
+++ b/spec/lib/diaspora_federation/entities/comment_spec.rb
@@ -3,8 +3,9 @@ module DiasporaFederation
     let(:parent) { FactoryGirl.create(:post, author: bob) }
     let(:parent_entity) { FactoryGirl.build(:related_entity, author: bob.diaspora_id) }
     let(:data) {
-      FactoryGirl.build(:comment_entity, author: alice.diaspora_id, parent_guid: parent.guid, parent: parent_entity)
-                 .send(:enriched_properties).merge(created_at: Time.now.utc, parent: parent_entity)
+      add_signatures(
+        FactoryGirl.build(:comment_entity, author: alice.diaspora_id, parent_guid: parent.guid, parent: parent_entity)
+      )
     }
 
     let(:xml) { <<-XML }
@@ -33,14 +34,14 @@ XML
       end
 
       it "parses the created_at from the xml if it is included and correctly signed" do
-        created_at = Time.now.utc - 1.minute
+        created_at = Time.now.utc.change(usec: 0) - 1.minute
         comment_data = FactoryGirl.build(:comment_entity, author: alice.diaspora_id, parent_guid: parent.guid).to_h
         comment_data[:created_at] = created_at
         comment_data[:parent] = parent_entity
         comment = described_class.new(comment_data, %i(author guid parent_guid text created_at))
 
         parsed_comment = described_class.from_xml(comment.to_xml)
-        expect(parsed_comment.created_at).to eq(created_at.to_s)
+        expect(parsed_comment.created_at).to eq(created_at)
       end
     end
   end
diff --git a/spec/lib/diaspora_federation/entities/conversation_spec.rb b/spec/lib/diaspora_federation/entities/conversation_spec.rb
index 903053e..c618fca 100644
--- a/spec/lib/diaspora_federation/entities/conversation_spec.rb
+++ b/spec/lib/diaspora_federation/entities/conversation_spec.rb
@@ -3,12 +3,14 @@ module DiasporaFederation
     let(:parent) { FactoryGirl.create(:conversation, author: bob) }
     let(:parent_entity) { FactoryGirl.build(:related_entity, author: bob.diaspora_id) }
     let(:signed_msg1) {
-      FactoryGirl.build(:message_entity, author: bob.diaspora_id, parent_guid: parent.guid, parent: parent_entity)
-                 .send(:enriched_properties).merge(parent: parent_entity)
+      add_signatures(
+        FactoryGirl.build(:message_entity, author: bob.diaspora_id, parent_guid: parent.guid, parent: parent_entity)
+      )
     }
     let(:signed_msg2) {
-      FactoryGirl.build(:message_entity, author: bob.diaspora_id, parent_guid: parent.guid, parent: parent_entity)
-                 .send(:enriched_properties).merge(parent: parent_entity)
+      add_signatures(
+        FactoryGirl.build(:message_entity, author: bob.diaspora_id, parent_guid: parent.guid, parent: parent_entity)
+      )
     }
     let(:data) {
       FactoryGirl.attributes_for(:conversation_entity).merge!(
@@ -24,7 +26,7 @@ module DiasporaFederation
   <diaspora_handle>#{data[:author]}</diaspora_handle>
   <guid>#{parent.guid}</guid>
   <subject>#{data[:subject]}</subject>
-  <created_at>#{data[:created_at]}</created_at>
+  <created_at>#{data[:created_at].utc.iso8601}</created_at>
   <participant_handles>#{data[:participants]}</participant_handles>
 #{data[:messages].map {|a| a.to_xml.to_s.indent(2) }.join("\n")}
 </conversation>
diff --git a/spec/lib/diaspora_federation/entities/like_spec.rb b/spec/lib/diaspora_federation/entities/like_spec.rb
index c298112..64bab59 100644
--- a/spec/lib/diaspora_federation/entities/like_spec.rb
+++ b/spec/lib/diaspora_federation/entities/like_spec.rb
@@ -3,13 +3,15 @@ module DiasporaFederation
     let(:parent) { FactoryGirl.create(:post, author: bob) }
     let(:parent_entity) { FactoryGirl.build(:related_entity, author: bob.diaspora_id) }
     let(:data) {
-      FactoryGirl.build(
-        :like_entity,
-        author:      alice.diaspora_id,
-        parent_guid: parent.guid,
-        parent_type: parent.entity_type,
-        parent:      parent_entity
-      ).send(:enriched_properties).merge(parent: parent_entity)
+      add_signatures(
+        FactoryGirl.build(
+          :like_entity,
+          author:      alice.diaspora_id,
+          parent_guid: parent.guid,
+          parent_type: parent.entity_type,
+          parent:      parent_entity
+        )
+      )
     }
 
     let(:xml) { <<-XML }
diff --git a/spec/lib/diaspora_federation/entities/message_spec.rb b/spec/lib/diaspora_federation/entities/message_spec.rb
index 1fa9b1b..b2a54ef 100644
--- a/spec/lib/diaspora_federation/entities/message_spec.rb
+++ b/spec/lib/diaspora_federation/entities/message_spec.rb
@@ -3,8 +3,9 @@ module DiasporaFederation
     let(:parent) { FactoryGirl.create(:conversation, author: bob) }
     let(:parent_entity) { FactoryGirl.build(:related_entity, author: bob.diaspora_id) }
     let(:data) {
-      FactoryGirl.build(:message_entity, author: alice.diaspora_id, parent_guid: parent.guid, parent: parent_entity)
-                 .send(:enriched_properties).merge(parent: parent_entity)
+      add_signatures(
+        FactoryGirl.build(:message_entity, author: alice.diaspora_id, parent_guid: parent.guid, parent: parent_entity)
+      )
     }
 
     let(:xml) { <<-XML }
@@ -36,19 +37,19 @@ XML
       end
 
       it "allows parent author if the signature is valid" do
-        expect_callback(:fetch_related_entity, "Conversation", entity.conversation_guid).and_return(data[:parent])
+        expect_callback(:fetch_related_entity, "Conversation", entity.conversation_guid).and_return(parent_entity)
         expect_callback(:fetch_public_key, alice.diaspora_id).and_return(alice.private_key)
         expect(entity.sender_valid?(bob.diaspora_id)).to be_truthy
       end
 
       it "does not allow any other person" do
-        expect_callback(:fetch_related_entity, "Conversation", entity.conversation_guid).and_return(data[:parent])
+        expect_callback(:fetch_related_entity, "Conversation", entity.conversation_guid).and_return(parent_entity)
         invalid_sender = FactoryGirl.generate(:diaspora_id)
         expect(entity.sender_valid?(invalid_sender)).to be_falsey
       end
 
       it "does not allow the parent author if the signature is invalid" do
-        expect_callback(:fetch_related_entity, "Conversation", entity.conversation_guid).and_return(data[:parent])
+        expect_callback(:fetch_related_entity, "Conversation", entity.conversation_guid).and_return(parent_entity)
         expect_callback(:fetch_public_key, alice.diaspora_id).and_return(alice.private_key)
         invalid_msg = Entities::Message.new(data.merge(author_signature: "aa"))
         expect {
diff --git a/spec/lib/diaspora_federation/entities/participation_spec.rb b/spec/lib/diaspora_federation/entities/participation_spec.rb
index 19e51b3..ebd32af 100644
--- a/spec/lib/diaspora_federation/entities/participation_spec.rb
+++ b/spec/lib/diaspora_federation/entities/participation_spec.rb
@@ -3,13 +3,15 @@ module DiasporaFederation
     let(:parent) { FactoryGirl.create(:post, author: bob) }
     let(:parent_entity) { FactoryGirl.build(:related_entity, author: bob.diaspora_id) }
     let(:data) {
-      FactoryGirl.build(
-        :participation_entity,
-        author:      alice.diaspora_id,
-        parent_guid: parent.guid,
-        parent_type: parent.entity_type,
-        parent:      parent_entity
-      ).send(:enriched_properties).merge(parent: parent_entity)
+      add_signatures(
+        FactoryGirl.build(
+          :participation_entity,
+          author:      alice.diaspora_id,
+          parent_guid: parent.guid,
+          parent_type: parent.entity_type,
+          parent:      parent_entity
+        )
+      )
     }
 
     let(:xml) { <<-XML }
diff --git a/spec/lib/diaspora_federation/entities/photo_spec.rb b/spec/lib/diaspora_federation/entities/photo_spec.rb
index 92ba840..a9db12e 100644
--- a/spec/lib/diaspora_federation/entities/photo_spec.rb
+++ b/spec/lib/diaspora_federation/entities/photo_spec.rb
@@ -7,7 +7,7 @@ module DiasporaFederation
   <guid>#{data[:guid]}</guid>
   <diaspora_handle>#{data[:author]}</diaspora_handle>
   <public>#{data[:public]}</public>
-  <created_at>#{data[:created_at]}</created_at>
+  <created_at>#{data[:created_at].utc.iso8601}</created_at>
   <remote_photo_path>#{data[:remote_photo_path]}</remote_photo_path>
   <remote_photo_name>#{data[:remote_photo_name]}</remote_photo_name>
   <text>#{data[:text]}</text>
diff --git a/spec/lib/diaspora_federation/entities/poll_participation_spec.rb b/spec/lib/diaspora_federation/entities/poll_participation_spec.rb
index dd2361f..9a0b8b5 100644
--- a/spec/lib/diaspora_federation/entities/poll_participation_spec.rb
+++ b/spec/lib/diaspora_federation/entities/poll_participation_spec.rb
@@ -3,12 +3,14 @@ module DiasporaFederation
     let(:parent) { FactoryGirl.create(:poll, author: bob) }
     let(:parent_entity) { FactoryGirl.build(:related_entity, author: bob.diaspora_id) }
     let(:data) {
-      FactoryGirl.build(
-        :poll_participation_entity,
-        author:      alice.diaspora_id,
-        parent_guid: parent.guid,
-        parent:      parent_entity
-      ).send(:enriched_properties).merge(parent: parent_entity)
+      add_signatures(
+        FactoryGirl.build(
+          :poll_participation_entity,
+          author:      alice.diaspora_id,
+          parent_guid: parent.guid,
+          parent:      parent_entity
+        )
+      )
     }
 
     let(:xml) { <<-XML }
diff --git a/spec/lib/diaspora_federation/entities/relayable_spec.rb b/spec/lib/diaspora_federation/entities/relayable_spec.rb
index 1420926..5512f1b 100644
--- a/spec/lib/diaspora_federation/entities/relayable_spec.rb
+++ b/spec/lib/diaspora_federation/entities/relayable_spec.rb
@@ -21,7 +21,7 @@ module DiasporaFederation
 
       include Entities::Relayable
 
-      property :property
+      property :property, :string
 
       def parent_type
         PARENT_TYPE
diff --git a/spec/lib/diaspora_federation/entities/reshare_spec.rb b/spec/lib/diaspora_federation/entities/reshare_spec.rb
index 8b32927..d1efba8 100644
--- a/spec/lib/diaspora_federation/entities/reshare_spec.rb
+++ b/spec/lib/diaspora_federation/entities/reshare_spec.rb
@@ -7,7 +7,7 @@ module DiasporaFederation
 <reshare>
   <diaspora_handle>#{data[:author]}</diaspora_handle>
   <guid>#{data[:guid]}</guid>
-  <created_at>#{data[:created_at]}</created_at>
+  <created_at>#{data[:created_at].utc.iso8601}</created_at>
   <provider_display_name>#{data[:provider_display_name]}</provider_display_name>
   <root_diaspora_id>#{data[:root_author]}</root_diaspora_id>
   <root_guid>#{data[:root_guid]}</root_guid>
diff --git a/spec/lib/diaspora_federation/entities/status_message_spec.rb b/spec/lib/diaspora_federation/entities/status_message_spec.rb
index 1215e24..25b7473 100644
--- a/spec/lib/diaspora_federation/entities/status_message_spec.rb
+++ b/spec/lib/diaspora_federation/entities/status_message_spec.rb
@@ -17,14 +17,14 @@ module DiasporaFederation
 <status_message>
   <diaspora_handle>#{data[:author]}</diaspora_handle>
   <guid>#{data[:guid]}</guid>
-  <created_at>#{data[:created_at]}</created_at>
+  <created_at>#{data[:created_at].utc.iso8601}</created_at>
   <provider_display_name>#{data[:provider_display_name]}</provider_display_name>
   <raw_message>#{data[:text]}</raw_message>
   <photo>
     <guid>#{photo1.guid}</guid>
     <diaspora_handle>#{photo1.author}</diaspora_handle>
     <public>#{photo1.public}</public>
-    <created_at>#{photo1.created_at}</created_at>
+    <created_at>#{photo1.created_at.utc.iso8601}</created_at>
     <remote_photo_path>#{photo1.remote_photo_path}</remote_photo_path>
     <remote_photo_name>#{photo1.remote_photo_name}</remote_photo_name>
     <text>#{photo1.text}</text>
@@ -36,7 +36,7 @@ module DiasporaFederation
     <guid>#{photo2.guid}</guid>
     <diaspora_handle>#{photo2.author}</diaspora_handle>
     <public>#{photo2.public}</public>
-    <created_at>#{photo2.created_at}</created_at>
+    <created_at>#{photo2.created_at.utc.iso8601}</created_at>
     <remote_photo_path>#{photo2.remote_photo_path}</remote_photo_path>
     <remote_photo_name>#{photo2.remote_photo_name}</remote_photo_name>
     <text>#{photo2.text}</text>
diff --git a/spec/lib/diaspora_federation/entity_spec.rb b/spec/lib/diaspora_federation/entity_spec.rb
index 8d0c6ba..0411bab 100644
--- a/spec/lib/diaspora_federation/entity_spec.rb
+++ b/spec/lib/diaspora_federation/entity_spec.rb
@@ -175,6 +175,23 @@ XML
           expect(entity.test).to eq("asdf")
           expect(entity.qwer).to eq("qwer")
         end
+
+        it "parses the string to the correct type" do
+          xml = <<-XML.strip
+<test_default_entity>
+  <test1>asdf</test1>
+  <test2>qwer</qwer2>
+  <test3>true</qwer3>
+</test_default_entity>
+XML
+
+          entity = Entities::TestDefaultEntity.from_xml(Nokogiri::XML::Document.parse(xml).root)
+
+          expect(entity).to be_an_instance_of Entities::TestDefaultEntity
+          expect(entity.test1).to eq("asdf")
+          expect(entity.test2).to eq("qwer")
+          expect(entity.test3).to eq(true)
+        end
       end
 
       context "nested entities" do
diff --git a/spec/lib/diaspora_federation/federation/fetcher_spec.rb b/spec/lib/diaspora_federation/federation/fetcher_spec.rb
index d1c5898..b04b170 100644
--- a/spec/lib/diaspora_federation/federation/fetcher_spec.rb
+++ b/spec/lib/diaspora_federation/federation/fetcher_spec.rb
@@ -19,7 +19,7 @@ module DiasporaFederation
           expect(magic_env.payload.guid).to eq(post.guid)
           expect(magic_env.payload.author).to eq(post.author)
           expect(magic_env.payload.text).to eq(post.text)
-          expect(magic_env.payload.public).to eq("true")
+          expect(magic_env.payload.public).to eq(post.public)
           receiver
         end
         expect(receiver).to receive(:receive)
@@ -42,7 +42,7 @@ module DiasporaFederation
           expect(magic_env.payload.guid).to eq(post.guid)
           expect(magic_env.payload.author).to eq(post.author)
           expect(magic_env.payload.text).to eq(post.text)
-          expect(magic_env.payload.public).to eq("true")
+          expect(magic_env.payload.public).to eq(post.public)
           receiver
         end
         expect(receiver).to receive(:receive)
diff --git a/spec/lib/diaspora_federation/properties_dsl_spec.rb b/spec/lib/diaspora_federation/properties_dsl_spec.rb
index 5edf088..e4442c7 100644
--- a/spec/lib/diaspora_federation/properties_dsl_spec.rb
+++ b/spec/lib/diaspora_federation/properties_dsl_spec.rb
@@ -4,43 +4,59 @@ module DiasporaFederation
 
     context "simple properties" do
       it "can name simple properties by symbol" do
-        dsl.property :test
+        dsl.property :test, :string
         properties = dsl.class_props
         expect(properties).to have(1).item
-        expect(properties[:test]).to eq(String)
+        expect(properties[:test]).to eq(:string)
         expect(dsl.xml_names[:test]).to eq(:test)
       end
 
       it "will not accept other types for names" do
         ["test", 1234, true, {}].each do |val|
           expect {
-            dsl.property val
+            dsl.property val, :string
           }.to raise_error PropertiesDSL::InvalidName
         end
       end
 
+      it "will not accept other types for type" do
+        ["test", 1234, true, {}].each do |val|
+          expect {
+            dsl.property :fail, val
+          }.to raise_error PropertiesDSL::InvalidType
+        end
+      end
+
+      it "accepts only supported types" do
+        %i(text number foobar).each do |val|
+          expect {
+            dsl.property :fail, val
+          }.to raise_error PropertiesDSL::InvalidType
+        end
+      end
+
       it "can define multiple properties" do
-        dsl.property :test
-        dsl.property :asdf
-        dsl.property :zzzz
+        dsl.property :test, :string
+        dsl.property :asdf, :string
+        dsl.property :zzzz, :string
         properties = dsl.class_props
         expect(properties).to have(3).items
         expect(properties.keys).to include(:test, :asdf, :zzzz)
-        properties.values.each {|type| expect(type).to eq(String) }
+        properties.values.each {|type| expect(type).to eq(:string) }
       end
 
       it "can add an xml name to simple properties with a symbol" do
-        dsl.property :test, xml_name: :xml_test
+        dsl.property :test, :string, xml_name: :xml_test
         properties = dsl.class_props
         expect(properties).to have(1).item
-        expect(properties[:test]).to eq(String)
+        expect(properties[:test]).to eq(:string)
         expect(dsl.xml_names[:test]).to eq(:xml_test)
       end
 
       it "will not accept other types for xml names" do
         ["test", 1234, true, {}].each do |val|
           expect {
-            dsl.property :test, xml_name: val
+            dsl.property :test, :string, xml_name: val
           }.to raise_error PropertiesDSL::InvalidName, "invalid xml_name"
         end
       end
@@ -91,13 +107,13 @@ module DiasporaFederation
 
     describe ".default_values" do
       it "can accept default values" do
-        dsl.property :test, default: :foobar
+        dsl.property :test, :string, default: :foobar
         defaults = dsl.default_values
         expect(defaults[:test]).to eq(:foobar)
       end
 
       it "can accept default blocks" do
-        dsl.property :test, default: -> { "default" }
+        dsl.property :test, :string, default: -> { "default" }
         defaults = dsl.default_values
         expect(defaults[:test]).to eq("default")
       end
@@ -105,27 +121,27 @@ module DiasporaFederation
 
     describe ".resolv_aliases" do
       it "resolves the defined alias" do
-        dsl.property :test, alias: :test_alias
+        dsl.property :test, :string, alias: :test_alias
         data = dsl.resolv_aliases(test_alias: "foo")
         expect(data[:test]).to eq("foo")
         expect(data).not_to have_key(:test_alias)
       end
 
       it "raises when alias and original property are present" do
-        dsl.property :test, alias: :test_alias
+        dsl.property :test, :string, alias: :test_alias
         expect {
           dsl.resolv_aliases(test_alias: "foo", test: "bar")
         }.to raise_error PropertiesDSL::InvalidData, "only use 'test_alias' OR 'test'"
       end
 
       it "returns original data if no alias is defined" do
-        dsl.property :test, alias: :test_alias
+        dsl.property :test, :string, alias: :test_alias
         data = dsl.resolv_aliases(test: "foo")
         expect(data[:test]).to eq("foo")
       end
 
       it "returns original data if alias is defined, but not present" do
-        dsl.property :test
+        dsl.property :test, :string
         data = dsl.resolv_aliases(test: "foo")
         expect(data[:test]).to eq("foo")
         expect(data).not_to have_key(:test_alias)
@@ -134,17 +150,17 @@ module DiasporaFederation
 
     describe ".find_property_for_xml_name" do
       it "finds property by xml_name" do
-        dsl.property :test, xml_name: :xml_test
+        dsl.property :test, :string, xml_name: :xml_test
         expect(dsl.find_property_for_xml_name("xml_test")).to eq(:test)
       end
 
       it "finds property by name" do
-        dsl.property :test, xml_name: :xml_test
+        dsl.property :test, :string, xml_name: :xml_test
         expect(dsl.find_property_for_xml_name("test")).to eq(:test)
       end
 
       it "returns nil if property is not defined" do
-        dsl.property :test, xml_name: :xml_test
+        dsl.property :test, :string, xml_name: :xml_test
         expect(dsl.find_property_for_xml_name("unknown")).to be_nil
       end
     end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 32a75b2..32bcec1 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -38,6 +38,14 @@ def expect_callback(*opts)
   expect(DiasporaFederation.callbacks).to receive(:trigger).with(*opts)
 end
 
+def add_signatures(entity)
+  properties = entity.send(:enriched_properties)
+  entity.to_h.tap do |hash|
+    hash[:author_signature] = properties[:author_signature]
+    hash[:parent_author_signature] = properties[:parent_author_signature]
+  end
+end
+
 # Requires supporting files with custom matchers and macros, etc,
 # in ./support/ and its subdirectories.
 fixture_builder_file = "#{File.dirname(__FILE__)}/support/fixture_builder.rb"
diff --git a/spec/support/shared_entity_specs.rb b/spec/support/shared_entity_specs.rb
index 6a29bd1..ad750cf 100644
--- a/spec/support/shared_entity_specs.rb
+++ b/spec/support/shared_entity_specs.rb
@@ -75,14 +75,22 @@ shared_examples "an XML Entity" do |ignored_props=[]|
   def validate_values(value, parsed_value, type, ignored_props)
     if value.nil?
       expect(parsed_value).to be_nil
-    elsif type == String
-      expect(parsed_value.to_s).to eq(value.to_s)
+    elsif type.instance_of?(Symbol)
+      validate_property(value, parsed_value)
     elsif type.instance_of?(Array)
       value.each_with_index {|entity, index| check_entity(entity, parsed_value[index], ignored_props) }
     elsif type.ancestors.include?(DiasporaFederation::Entity)
       check_entity(value, parsed_value, ignored_props)
     end
   end
+
+  def validate_property(value, parsed_value)
+    if value.is_a?(Time)
+      expect(parsed_value).to eq(value.change(usec: 0))
+    else
+      expect(parsed_value).to eq(value)
+    end
+  end
 end
 
 shared_examples "a relayable Entity" do