User: generate private keys on user creation

This fixes a race condition bug where keys could be regenerated
post-federation, causing activities and HTTP signatures from an user to
be dropped due to key differences.

lib/pleroma/user.ex

@@ -711,6 +711,7 @@ defmodule Pleroma.User do
     |> put_ap_id()
     |> unique_constraint(:ap_id)
     |> put_following_and_follower_and_featured_address()
+    |> put_private_key()
   end
 
   def register_changeset(struct, params \\ %{}, opts \\ []) do
@@ -768,6 +769,7 @@ defmodule Pleroma.User do
     |> put_ap_id()
     |> unique_constraint(:ap_id)
     |> put_following_and_follower_and_featured_address()
+    |> put_private_key()
   end
 
   def validate_not_restricted_nickname(changeset, field) do
@@ -846,6 +848,11 @@ defmodule Pleroma.User do
     |> put_change(:featured_address, featured)
   end
 
+  defp put_private_key(changeset) do
+    {:ok, pem} = Keys.generate_rsa_pem()
+    put_change(changeset, :keys, pem)
+  end
+
   defp autofollow_users(user) do
     candidates = Config.get([:instance, :autofollowed_nicknames])
 
@@ -2086,6 +2093,7 @@ defmodule Pleroma.User do
       follower_address: uri <> "/followers"
     }
     |> change
+    |> put_private_key()
     |> unique_constraint(:nickname)
     |> Repo.insert()
     |> set_cache()
@@ -2351,17 +2359,6 @@ defmodule Pleroma.User do
     }
   end
 
-  def ensure_keys_present(%{keys: keys} = user) when not is_nil(keys), do: {:ok, user}
-
-  def ensure_keys_present(%User{} = user) do
-    with {:ok, pem} <- Keys.generate_rsa_pem() do
-      user
-      |> cast(%{keys: pem}, [:keys])
-      |> validate_required([:keys])
-      |> update_and_set_cache()
-    end
-  end
-
   def get_ap_ids_by_nicknames(nicknames) do
     from(u in User,
       where: u.nickname in ^nicknames,