POT

Introduction

POT is an Erlang library for generating one time passwords. It supports both HMAC-based one time passwords (HOTP) and time based ones (TOTP). The generated passwords are compatible with Google Authenticator.

POT is an almost direct translation of the Python OneTimePass library.

POT should work with any recent version of Erlang/OTP, Elixir and other Erlang VM based languages.

In order to learn more about one time password generation, see the following Wikipedia articles:

• Google Authenticator
• HMAC-based One-time Password Algorithm
• Time-based One-time Password Algorithm

TODO

• Documentation.

News

• 2016/07/30
  • Released version 0.9.5 with bug fixes (Thanks to Peter McLain)
• 2015/01/20
  • Embedded base32_erlang library
• 2015/01/18
  • Initial version

Usage (Erlang)

We recommend using rebar3 for managing dependencies and building the library. POT is available on hex.pm, so you can just include the following in your rebar.config:

{deps, [pot]}.

POT works with binary tokens and secrets.

Create a time based token

Secret = <<"MFRGGZDFMZTWQ2LK">>,
Token = pot:totp(Secret),
% Do something with the token

Create an HMAC based token

Secret = <<"MFRGGZDFMZTWQ2LK">>,
CurrentTrial = 3,
Token = pot:hotp(Secret, CurrentTrial),
% Do something with the token

Check some time based token

Secret = <<"MFRGGZDFMZTWQ2LK">>,
Token = <<"123456">>,
IsValid = pot:valid_totp(Token, Secret),
% Do something

Check some HMAC based token

Secret = <<"MFRGGZDFMZTWQ2LK">>,
Token = <<"123456">>,
LastUsed = 5,  % last successful trial
IsValid = pot:valid_hotp(Token, Secret, [{last, LastUsed}]),
% Do something

Usage (Elixir)

Include POT in your mix.exs as a dependency:

defp deps do
    [{:pot, "~>0.9.5"}]
end

Create a time based token

secret = "MFRGGZDFMZTWQ2LK"
token = :pot.totp(secret)
# Do something with the token

Create an HMAC based token

secret = "MFRGGZDFMZTWQ2LK"
current_trial = 3
token = :pot.hotp(secret, current_trial)
# Do something with the token

Check some time based token

secret = "MFRGGZDFMZTWQ2LK"
token = "123456"
is_valid = :pot.valid_totp(token, secret)
# Do something

Check some HMAC based token

secret = "MFRGGZDFMZTWQ2LK"
token = "123456"
last_used = 5  # last successful trial
is_valid = :pot.valid_hotp(token, secret, [{:last, last_used}])
# Do something

Credits

• Yuce Tekol
• Tomasz Jaskowski: OneTimePass Python library
• Andrew Tunnell-Jones: base32_erlang library

License

Copyright (c) 2014-2016 Yüce Tekol

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.