1 # Pleroma: A lightweight social networking server
2 # Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
3 # SPDX-License-Identifier: AGPL-3.0-only
5 # https://tools.ietf.org/html/draft-cavage-http-signatures-08
6 defmodule Pleroma.Web.HTTPSignatures do
8 alias Pleroma.Web.ActivityPub.Utils
9 alias Pleroma.Web.ActivityPub.ActivityPub
12 def split_signature(sig) do
13 default = %{"headers" => "date"}
19 |> Enum.reduce(default, fn part, acc ->
20 [key | rest] = String.split(part, "=")
21 value = Enum.join(rest, "=")
22 Map.put(acc, key, String.trim(value, "\""))
25 Map.put(sig, "headers", String.split(sig["headers"], ~r/\s/))
28 def validate(headers, signature, public_key) do
29 sigstring = build_signing_string(headers, signature["headers"])
30 Logger.debug("Signature: #{signature["signature"]}")
31 Logger.debug("Sigstring: #{sigstring}")
32 {:ok, sig} = Base.decode64(signature["signature"])
33 :public_key.verify(sigstring, :sha256, sig, public_key)
36 def validate_conn(conn) do
37 # TODO: How to get the right key and see if it is actually valid for that request.
38 # For now, fetch the key for the actor.
39 with actor_id <- Utils.get_ap_id(conn.params["actor"]),
40 {:ok, public_key} <- User.get_public_key_for_ap_id(actor_id) do
41 if validate_conn(conn, public_key) do
44 Logger.debug("Could not validate, re-fetching user and trying one more time")
45 # Fetch user anew and try one more time
46 with actor_id <- Utils.get_ap_id(conn.params["actor"]),
47 {:ok, _user} <- ActivityPub.make_user_from_ap_id(actor_id),
48 {:ok, public_key} <- User.get_public_key_for_ap_id(actor_id) do
49 validate_conn(conn, public_key)
54 Logger.debug("Could not public key!")
59 def validate_conn(conn, public_key) do
60 headers = Enum.into(conn.req_headers, %{})
61 signature = split_signature(headers["signature"])
62 validate(headers, signature, public_key)
65 def build_signing_string(headers, used_headers) do
67 |> Enum.map(fn header -> "#{header}: #{headers[header]}" end)
71 def sign(user, headers) do
72 with {:ok, %{info: %{keys: keys}}} <- Pleroma.Web.WebFinger.ensure_keys_present(user),
73 {:ok, private_key, _} = Pleroma.Web.Salmon.keys_from_pem(keys) do
74 sigstring = build_signing_string(headers, Map.keys(headers))
77 :public_key.sign(sigstring, :sha256, private_key)
81 keyId: user.ap_id <> "#main-key",
82 algorithm: "rsa-sha256",
83 headers: Map.keys(headers) |> Enum.join(" "),
86 |> Enum.map(fn {k, v} -> "#{k}=\"#{v}\"" end)