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# Pleroma: A lightweight social networking server
# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.MFA.TOTP do
@moduledoc """
This module represents functions to create secrets for
TOTP Application as well as validate them with a time based token.
"""
alias Pleroma.Config
@config_ns [:instance, :multi_factor_authentication, :totp]
@doc """
https://github.com/google/google-authenticator/wiki/Key-Uri-Format
"""
def provisioning_uri(secret, label, opts \\ []) do
query =
%{
secret: secret,
issuer: Keyword.get(opts, :issuer, default_issuer()),
digits: Keyword.get(opts, :digits, default_digits()),
period: Keyword.get(opts, :period, default_period())
}
|> Enum.filter(fn {_, v} -> not is_nil(v) end)
|> Enum.into(%{})
|> URI.encode_query()
%URI{scheme: "otpauth", host: "totp", path: "/" <> label, query: query}
|> URI.to_string()
end
defp default_period, do: Config.get(@config_ns ++ [:period])
defp default_digits, do: Config.get(@config_ns ++ [:digits])
defp default_issuer,
do: Config.get(@config_ns ++ [:issuer], Config.get([:instance, :name]))
@doc "Creates a random Base 32 encoded string"
def generate_secret do
Base.encode32(:crypto.strong_rand_bytes(10))
end
@doc "Generates a valid token based on a secret"
def generate_token(secret) do
:pot.totp(secret)
end
@doc """
Validates a given token based on a secret.
optional parameters:
`token_length` default `6`
`interval_length` default `30`
`window` default 0
Returns {:ok, :pass} if the token is valid and
{:error, :invalid_token} if it is not.
"""
@spec validate_token(String.t(), String.t()) ::
{:ok, :pass} | {:error, :invalid_token | :invalid_secret_and_token}
def validate_token(secret, token)
when is_binary(secret) and is_binary(token) do
opts = [
token_length: default_digits(),
interval_length: default_period()
]
validate_token(secret, token, opts)
end
def validate_token(_, _), do: {:error, :invalid_secret_and_token}
@doc "See `validate_token/2`"
@spec validate_token(String.t(), String.t(), Keyword.t()) ::
{:ok, :pass} | {:error, :invalid_token | :invalid_secret_and_token}
def validate_token(secret, token, options)
when is_binary(secret) and is_binary(token) do
case :pot.valid_totp(token, secret, options) do
true -> {:ok, :pass}
false -> {:error, :invalid_token}
end
end
def validate_token(_, _, _), do: {:error, :invalid_secret_and_token}
end
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