diff --git a/includes/client/posts.php b/includes/client/posts.php
new file mode 100644
index 0000000..abcbbe8
--- /dev/null
+++ b/includes/client/posts.php
@@ -0,0 +1,63 @@
+<?php
+namespace posts;
+
+require_once plugin_dir_path( __FILE__ ) . '../server/activities/create.php';
+
+function handle_post_status_change( $new_status, $old_status, $post ) {
+    // TODO find a way to get the id of an existing object for the post, if it exists
+    $actor_slug = PTEROTYPE_BLOG_ACTOR_SLUG;
+    $actor_outbox = get_rest_url(
+        null, sprintf( 'pterotype/v1/actor/%s/outbox', $actor_slug )
+    );
+    $post_object = post_to_object( $post );
+    $activity = null;
+    if ( $new_status == 'publish' && $old_status != 'publish' ) {
+        // Create
+        $activity = \activities\create\make_create( $actor_slug, $post_object );
+    } else if ( $new_status == 'publish' && $old_status == 'publish' ) {
+        // Update
+        $activity = \activities\update\make_update( $actor_slug, $post_object );
+    } else if ( $new_status != 'publish' && $old_status == 'publish' ) {
+        // Delete
+        // TODO delete isn't working
+        $activity = \activities\delete\make_delete( $actor_slug, $post_object );
+    }
+    if ( $activity && ! is_wp_error( $activity ) ) {
+        $server = rest_get_server();
+        $request = \WP_REST_Request::from_url( $actor_outbox );
+        $request->set_method('POST');
+        $request->set_body( wp_json_encode( $activity ) );
+        $request->add_header( 'Content-Type', 'application/ld+json' );
+        $server->dispatch( $request );
+    }
+}
+
+/**
+Return an object of type Article
+*/
+function post_to_object( $post ) {
+    $object = array(
+        '@context' => array( 'https://www.w3.org/ns/activitystreams' ),
+        'type' => 'Article',
+        'name' => $post->post_title,
+        'content' => $post->post_content,
+        'attributedTo' => get_rest_url(
+            null, sprintf( '/pterotype/v1/actor/%s', PTEROTYPE_BLOG_ACTOR_SLUG )
+        ),
+        'url' => get_permalink( $post ),
+        'summary' => $post->post_excerpt,
+    );
+    $existing = get_existing_object( $post );
+    if ( $existing ) {
+        $object['id'] = $existing->activitypub_id;
+    }
+    return $object;
+}
+
+function get_existing_object( $post ) {
+    global $wpdb;
+    return $wpdb->get_row( $wpdb->prepare(
+        'SELECT * FROM pterotype_objects WHERE object->"$.url" = %s', get_permalink( $post )
+    ) );
+}
+?>
diff --git a/includes/init.php b/includes/init.php
index f07b1ed..8858c0d 100644
--- a/includes/init.php
+++ b/includes/init.php
@@ -5,6 +5,7 @@ require_once plugin_dir_path( __FILE__ ) . 'server/api.php';
 require_once plugin_dir_path( __FILE__ ) . 'server/actors.php';
 require_once plugin_dir_path( __FILE__ ) . 'migrations.php';
 require_once plugin_dir_path( __FILE__ ) . 'server/webfinger.php';
+require_once plugin_dir_path( __FILE__ ) . 'client/posts.php';
 
 add_action( 'rest_api_init', function() {
     \api\register_routes();
@@ -27,4 +28,5 @@ add_action( 'generate_rewrite_rules', '\webfinger\generate_rewrite_rules', 111 )
 add_action( 'parse_request', '\webfinger\parse_request', 111 );
 add_filter( 'query_vars', '\webfinger\query_vars' );
 add_action( 'well_known_webfinger', '\webfinger\handle' );
+add_action( 'transition_post_status', '\posts\handle_post_status_change', 10, 3 );
 ?>
diff --git a/includes/pgp.php b/includes/pgp.php
index 59dfb6a..f18f8ee 100644
--- a/includes/pgp.php
+++ b/includes/pgp.php
@@ -20,7 +20,6 @@ function persist_key( $actor_id, $public_key, $private_key ) {
 }
 
 function sign_data( $data, $actor_id ) {
-    xdebug_break();
     $secret_key = get_private_key( $actor_id );
     $sig = null;
     openssl_sign( $data, $sig, $secret_key );
@@ -30,7 +29,7 @@ function sign_data( $data, $actor_id ) {
             __( 'Unable to sign data', 'pterotype' )
         );
     }
-    return $sig;
+    return base64_encode( $sig );
 }
 
 function get_public_key( $actor_id ) {
diff --git a/includes/server/activities/create.php b/includes/server/activities/create.php
index 05bbf8b..27e19ac 100644
--- a/includes/server/activities/create.php
+++ b/includes/server/activities/create.php
@@ -2,6 +2,7 @@
 namespace activities\create;
 
 require_once plugin_dir_path( __FILE__ ) . '../objects.php';
+require_once plugin_dir_path( __FILE__ ) . '../actors.php';
 
 /*
 Create a new post or comment (depending on $activity["object"]["type"]),
@@ -88,4 +89,18 @@ function scrub_object( $object ) {
     unset( $object['bto'] );
     return $object;
 }
+
+function make_create( $actor_slug, $object ) {
+    $actor = \actors\get_actor_by_slug( $actor_slug );
+    if ( is_wp_error( $actor ) ) {
+        return $actor;
+    }
+    $activity = array(
+        '@context' => 'https://www.w3.org/ns/activitystreams',
+        'type' => 'Create',
+        'actor' => $actor,
+        'object' => $object
+    );
+    return $activity;
+}
 ?>
diff --git a/includes/server/activities/delete.php b/includes/server/activities/delete.php
index 56ac0cd..c70b12b 100644
--- a/includes/server/activities/delete.php
+++ b/includes/server/activities/delete.php
@@ -2,6 +2,7 @@
 namespace activities\delete;
 
 require_once plugin_dir_path( __FILE__ ) . '../objects.php';
+require_once plugin_dir_path( __FILE__ ) . '../actors.php';
 
 function handle_outbox( $actor, $activity ) {
     if ( !array_key_exists( 'object', $activity ) ) {
@@ -66,4 +67,17 @@ function check_authorization( $activity ) {
     }
     return true;
 }
+
+function make_delete( $actor_slug, $object ) {
+    $actor = \actors\get_actor_by_slug( $actor_slug );
+    if ( is_wp_error( $actor ) ) {
+        return $actor;
+    }
+    return array(
+        '@context' => 'https://www.w3.org/ns/activitystreams',
+        'type' => 'Delete',
+        'actor' => $actor,
+        'object' => $object
+    );
+}
 ?>
diff --git a/includes/server/activities/update.php b/includes/server/activities/update.php
index 256e156..4b406ed 100644
--- a/includes/server/activities/update.php
+++ b/includes/server/activities/update.php
@@ -26,7 +26,7 @@ function handle_outbox( $actor_slug, $activity ) {
             array( 'status' => 400 )
         );
     }
-    $existing_object = \objects\get_object_by_actvitypub_id( $update_object['id'] );
+    $existing_object = \objects\get_object_by_activitypub_id( $update_object['id'] );
     if ( is_wp_error( $existing_object ) ) {
         return $existing_object;
     }
@@ -92,4 +92,17 @@ function check_authorization( $activity ) {
     }
     return true;
 }
+
+function make_update( $actor_slug, $object ) {
+    $actor = \actors\get_actor_by_slug( $actor_slug );
+    if ( is_wp_error( $actor ) ) {
+        return $actor;
+    }
+    return array(
+        '@context' => 'https://www.w3.org/ns/activitystreams',
+        'type' => 'Update',
+        'actor' => $actor,
+        'object' => $object
+    );
+}
 ?>
diff --git a/includes/server/inbox.php b/includes/server/inbox.php
index e52008d..1008578 100644
--- a/includes/server/inbox.php
+++ b/includes/server/inbox.php
@@ -24,6 +24,7 @@ require_once plugin_dir_path( __FILE__ ) . 'activities/undo.php';
 require_once plugin_dir_path( __FILE__ ) . '../util.php';
 
 function handle_activity( $actor_slug, $activity ) {
+    // TODO verify the authenticity of the activity
     $activity = \util\dereference_object( $activity );
     if ( !array_key_exists( 'type', $activity ) ) {
         return new \WP_Error(
diff --git a/includes/server/objects.php b/includes/server/objects.php
index abc4358..e0b33b2 100644
--- a/includes/server/objects.php
+++ b/includes/server/objects.php
@@ -145,25 +145,23 @@ function update_object( $object ) {
     $res = $wpdb->update(
         'pterotype_objects',
         array( 'object' => $object_json ),
-        array( 'id' => $id ),
+        array( 'activitypub_id' => $object['id'] ),
         '%s', '%d' );
     if ( !$res ) {
         return new \WP_Error(
             'db_error', __( 'Failed to update object row', 'pterotype' )
         );
     }
-    $activites_res = $wpdb->query( $wpdb->prepare(
-        '
-        UPDATE pterotype_activities
-        SET activity = JSON_SET(activity, "$.object", %s)
-        WHERE activity->"$.object.id" = %s;
-        ',
-        $object_json, $object['id']
+    $referencing_activities = $wpdb->get_results( $wpdb->prepare(
+        'SELECT * FROM pterotype_activities WHERE activity->"$.object.id" = %s',
+        $object['id']
     ) );
-    if ( $activities_res === false ) {
-         return new \WP_Error(
-            'db_error', __( 'Failed to update associated activities', 'pterotype' )
-        );
+    if ( $referencing_activities ) {
+        foreach ( $referencing_activities as $activity_row ) {
+            $activity = json_decode( $activity_row->activity, true );
+            $activity['object'] = $object;
+            \activities\persist_activity( $activity );
+        }
     }
     return $object;
 }
diff --git a/includes/server/outbox.php b/includes/server/outbox.php
index e3cfdee..3966330 100644
--- a/includes/server/outbox.php
+++ b/includes/server/outbox.php
@@ -182,16 +182,6 @@ function persist_activity( $actor_slug, $activity ) {
 }
 
 function wrap_object_in_create( $actor_slug, $object ) {
-    $actor = \actors\get_actor_by_slug( $actor_slug );
-    if ( is_wp_error( $actor ) ) {
-        return $actor;
-    }
-    $activity = array(
-        '@context' => 'https://www.w3.org/ns/activitystreams',
-        'type' => 'Create',
-        'actor' => $actor,
-        'object' => $object
-    );
-    return $activity;
+    return \activities\create\make_create( $actor_slug, $object );
 }
 ?>