add signature verification with gpg_ex

lib/nodelix/node_downloader.ex

@@ -7,7 +7,7 @@ defmodule Nodelix.NodeDownloader do
   @checksums_signature_base_url "https://nodejs.org/dist/v$version/SHASUMS256.txt.sig"
 
   @signing_keys_list_url "https://raw.githubusercontent.com/nodejs/release-keys/main/keys.list"
-  @signing_keys_dir_url "https://raw.githubusercontent.com/nodejs/release-keys/main/keys"
+  @signing_key_base_url "https://raw.githubusercontent.com/nodejs/release-keys/main/keys/$key_id.asc"
 
   require Logger
 
@@ -71,21 +71,46 @@ defmodule Nodelix.NodeDownloader do
   def install(archive_base_url \\ @default_archive_base_url) do
     fetch_archive(archive_base_url)
     fetch_checksums_and_signature()
-    _signing_keys = fetch_signing_keys()
+    %{checksums: checksums_path, signature: signature_path} = paths()
+
+    verify_signature!(checksums_path, signature_path)
+
+    Logger.debug("Signature ok!")
   end
 
-  defp fetch_signing_keys() do
-    Logger.debug("Downloading signing keys from #{@signing_keys_list_url}")
+  defp verify_signature!(file_path, signature_path) do
+    Logger.debug("Downloading signing keys list from #{@signing_keys_list_url}")
 
     signing_key_ids =
       @signing_keys_list_url
       |> HttpUtils.fetch_body!()
       |> String.trim()
       |> String.split("\n")
 
-    Enum.map(signing_key_ids, fn key_id ->
-      HttpUtils.fetch_body!("#{@signing_keys_dir_url}/#{key_id}.asc")
+    Logger.debug("Using GPG to retrieve signing keys")
+
+    %{path: keystore_path} = keystore = GPGex.Keystore.get_keystore_temp()
+
+    signing_key_ids
+    |> Enum.map(fn key_id ->
+      GPGex.cmd!(["--recv-keys", key_id], keystore: keystore)
     end)
+
+    case GPGex.cmd(
+           [
+             "--verify",
+             signature_path,
+             file_path
+           ],
+           keystore: keystore
+         ) do
+      {:ok, _, _} ->
+        File.rm_rf!(keystore_path)
+        :ok
+
+      {:error, _, _, _} ->
+        raise "invalid signature"
+    end
   end
 
   defp fetch_archive(archive_base_url) do

mix.exs

@@ -53,6 +53,7 @@ defmodule Nodelix.MixProject do
 
   defp deps do
     [
+      {:gpg_ex, "1.0.0-alpha.3"},
       {:castore, "~> 1.0"},
       {:ex_doc, ">= 0.0.0", only: :dev, runtime: false}
     ]

mix.lock

@@ -1,7 +1,9 @@
 %{
   "castore": {:hex, :castore, "1.0.4", "ff4d0fb2e6411c0479b1d965a814ea6d00e51eb2f58697446e9c41a97d940b28", [:mix], [], "hexpm", "9418c1b8144e11656f0be99943db4caf04612e3eaecefb5dae9a2a87565584f8"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.38", "b42252eddf63bda05554ba8be93a1262dc0920c721f1aaf989f5de0f73a2e367", [:mix], [], "hexpm", "2cd0907795aaef0c7e8442e376633c5b3bd6edc8dbbdc539b22f095501c1cdb6"},
+  "elixir_uuid": {:hex, :elixir_uuid, "1.2.1", "dce506597acb7e6b0daeaff52ff6a9043f5919a4c3315abb4143f0b00378c097", [:mix], [], "hexpm", "f7eba2ea6c3555cea09706492716b0d87397b88946e6380898c2889d68585752"},
   "ex_doc": {:hex, :ex_doc, "0.30.9", "d691453495c47434c0f2052b08dd91cc32bc4e1a218f86884563448ee2502dd2", [:mix], [{:earmark_parser, "~> 1.4.31", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1", [hex: :makeup_erlang, repo: "hexpm", optional: false]}], "hexpm", "d7aaaf21e95dc5cddabf89063327e96867d00013963eadf2c6ad135506a8bc10"},
+  "gpg_ex": {:hex, :gpg_ex, "1.0.0-alpha.3", "d5860bb91b8c833441770f38707ad0556074ab5772f8e1dfc71ddedf7cae9e78", [:mix], [{:elixir_uuid, "~> 1.2", [hex: :elixir_uuid, repo: "hexpm", optional: false]}], "hexpm", "748d4283f0a62836afa07d27944f54c29cd6f02bd238ab1f72534f5273745630"},
   "makeup": {:hex, :makeup, "1.1.1", "fa0bc768698053b2b3869fa8a62616501ff9d11a562f3ce39580d60860c3a55e", [:mix], [{:nimble_parsec, "~> 1.2.2 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "5dc62fbdd0de44de194898b6710692490be74baa02d9d108bc29f007783b0b48"},
   "makeup_elixir": {:hex, :makeup_elixir, "0.16.1", "cc9e3ca312f1cfeccc572b37a09980287e243648108384b97ff2b76e505c3555", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "e127a341ad1b209bd80f7bd1620a15693a9908ed780c3b763bccf7d200c767c6"},
   "makeup_erlang": {:hex, :makeup_erlang, "0.1.2", "ad87296a092a46e03b7e9b0be7631ddcf64c790fa68a9ef5323b6cbb36affc72", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "f3f5a1ca93ce6e092d92b6d9c049bcda58a3b617a8d888f8e7231c85630e8108"},