PyOTP - The Python One-Time Password Library
********************************************

PyOTP is a Python library for generating and verifying one-time
passwords. It can be used to implement two-factor (2FA) or multi-
factor (MFA) authentication methods in web applications and in other
systems that require users to log in.

Open MFA standards are defined in RFC 4226 (HOTP: An HMAC-Based One-
Time Password Algorithm) and in RFC 6238 (TOTP: Time-Based One-Time
Password Algorithm). PyOTP implements server-side support for both of
these standards. Client-side support can be enabled by sending
authentication codes to users over SMS or email (HOTP) or, for TOTP,
by instructing users to use Google Authenticator, Authy, or another
compatible app. Users can set up auth tokens in their apps easily by
using their phone camera to scan otpauth:// QR codes provided by
PyOTP.

Implementers should read and follow the HOTP security requirements and
TOTP security considerations sections of the relevant RFCs. At
minimum, application implementers should follow this checklist:

* Ensure transport confidentiality by using HTTPS

* Ensure HOTP/TOTP secret confidentiality by storing secrets in a
  controlled access database

* Deny replay attacks by rejecting one-time passwords that have been
  used by the client (this requires storing the most recently
  authenticated timestamp, OTP, or hash of the OTP in your database,
  and rejecting the OTP when a match is seen)

* Throttle brute-force attacks against your application's login
  functionality

* When implementing a "greenfield" application, consider supporting
  FIDO U2F/WebAuthn in addition to HOTP/TOTP. U2F uses asymmetric
  cryptography to avoid using a shared secret design, which
  strengthens your MFA solution against server-side attacks. Hardware
  U2F also sequesters the client secret in a dedicated single-purpose
  device, which strengthens your clients against client-side attacks.
  And by automating scoping of credentials to relying party IDs
  (application origin/domain names), U2F adds protection against
  phishing attacks. One implementation of FIDO U2F/WebAuthn is PyOTP's
  sister project, PyWARP.

We also recommend that implementers read the OWASP Authentication
Cheat Sheet and NIST SP 800-63-3: Digital Authentication Guideline for
a high level overview of authentication best practices.


Quick overview of using One Time Passwords on your phone
========================================================

* OTPs involve a shared secret, stored both on the phone and the
  server

* OTPs can be generated on a phone without internet connectivity

* OTPs should always be used as a second factor of authentication (if
  your phone is lost, you account is still secured with a password)

* Google Authenticator and other OTP client apps allow you to store
  multiple OTP secrets and provision those using a QR Code


Installation
============

   pip install pyotp


Usage
=====


Time-based OTPs
---------------

   totp = pyotp.TOTP('base32secret3232')
   totp.now() # => '492039'

   # OTP verified for current time
   totp.verify('492039') # => True
   time.sleep(30)
   totp.verify('492039') # => False


Counter-based OTPs
------------------

   hotp = pyotp.HOTP('base32secret3232')
   hotp.at(0) # => '260182'
   hotp.at(1) # => '055283'
   hotp.at(1401) # => '316439'

   # OTP verified with a counter
   hotp.verify('316439', 1401) # => True
   hotp.verify('316439', 1402) # => False


Generating a Secret Key
-----------------------

A helper function is provided to generate a 16 character base32
secret, compatible with Google Authenticator and other OTP apps:

   pyotp.random_base32()

Some applications want the secret key to be formatted as a hex-encoded
string:

   pyotp.random_hex()  # returns a 32-character hex-encoded secret


Google Authenticator Compatible
-------------------------------

PyOTP works with the Google Authenticator iPhone and Android app, as
well as other OTP apps like Authy. PyOTP includes the ability to
generate provisioning URIs for use with the QR Code scanner built into
these MFA client apps:

   pyotp.totp.TOTP('JBSWY3DPEHPK3PXP').provisioning_uri(name='alice@google.com', issuer_name='Secure App')

   >>> 'otpauth://totp/Secure%20App:alice%40google.com?secret=JBSWY3DPEHPK3PXP&issuer=Secure%20App'

   pyotp.hotp.HOTP('JBSWY3DPEHPK3PXP').provisioning_uri(name="alice@google.com", issuer_name="Secure App", initial_count=0)

   >>> 'otpauth://hotp/Secure%20App:alice%40google.com?secret=JBSWY3DPEHPK3PXP&issuer=Secure%20App&counter=0'

This URL can then be rendered as a QR Code (for example, using
https://github.com/neocotic/qrious) which can then be scanned and
added to the users list of OTP credentials.

Parsing these URLs is also supported:

   pyotp.parse_uri('otpauth://totp/Secure%20App:alice%40google.com?secret=JBSWY3DPEHPK3PXP&issuer=Secure%20App')

   >>> <pyotp.totp.TOTP object at 0xFFFFFFFF>

   pyotp.parse_uri('otpauth://hotp/Secure%20App:alice%40google.com?secret=JBSWY3DPEHPK3PXP&issuer=Secure%20App&counter=0'

   >>> <pyotp.totp.HOTP object at 0xFFFFFFFF>


Working example
---------------

Scan the following barcode with your phone's OTP app (e.g. Google
Authenticator):

[image]

Now run the following and compare the output:

   import pyotp
   totp = pyotp.TOTP("JBSWY3DPEHPK3PXP")
   print("Current OTP:", totp.now())


Links
-----

* Project home page (GitHub)

* Documentation

* Package distribution (PyPI)

* Change log

* RFC 4226: HOTP: An HMAC-Based One-Time Password

* RFC 6238: TOTP: Time-Based One-Time Password Algorithm

* ROTP - Original Ruby OTP library by Mark Percival

* OTPHP - PHP port of ROTP by Le Lag

* OWASP Authentication Cheat Sheet

* NIST SP 800-63-3: Digital Authentication Guideline

For new applications:

* WebAuthn

* PyWARP

[image][image][image][image][image]


API documentation
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*****************

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