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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.MFA.BackupCodes do
   6   @moduledoc """
   7   This module contains functions for generating backup codes.
   8   """
   9   alias Pleroma.Config
  10
  11   @config_ns [:instance, :multi_factor_authentication, :backup_codes]
  12
  13   @doc """
  14   Generates backup codes.
  15   """
  16   @spec generate(Keyword.t()) :: list(String.t())
  17   def generate(opts \\ []) do
  18     number_of_codes = Keyword.get(opts, :number_of_codes, default_backup_codes_number())
  19     code_length = Keyword.get(opts, :length, default_backup_codes_code_length())
  20
  21     Enum.map(1..number_of_codes, fn _ ->
  22       :crypto.strong_rand_bytes(div(code_length, 2))
  23       |> Base.encode16(case: :lower)
  24     end)
  25   end
  26
  27   defp default_backup_codes_number, do: Config.get(@config_ns ++ [:number], 5)
  28
  29   defp default_backup_codes_code_length,
  30     do: Config.get(@config_ns ++ [:length], 16)
  31 end