1 files changed, 31 insertions, 0 deletions
diff --git a/lib/pleroma/mfa/backup_codes.ex b/lib/pleroma/mfa/backup_codes.ex
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+++ b/lib/pleroma/mfa/backup_codes.ex
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+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.MFA.BackupCodes do
+  @moduledoc """
+  This module contains functions for generating backup codes.
+  """
+  alias Pleroma.Config
+
+  @config_ns [:instance, :multi_factor_authentication, :backup_codes]
+
+  @doc """
+  Generates backup codes.
+  """
+  @spec generate(Keyword.t()) :: list(String.t())
+  def generate(opts \\ []) do
+    number_of_codes = Keyword.get(opts, :number_of_codes, default_backup_codes_number())
+    code_length = Keyword.get(opts, :length, default_backup_codes_code_length())
+
+    Enum.map(1..number_of_codes, fn _ ->
+      :crypto.strong_rand_bytes(div(code_length, 2))
+      |> Base.encode16(case: :lower)
+    end)
+  end
+
+  defp default_backup_codes_number, do: Config.get(@config_ns ++ [:number], 5)
+
+  defp default_backup_codes_code_length,
+    do: Config.get(@config_ns ++ [:length], 16)
+end