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.

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 allows you to store multiple OTP secrets and provision those using a QR Code(no more typing in the secret)

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) # => 55283
hotp.at(1401) # => 316439

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

Generating a base32 Secret Key

pyotp.random_base32() # returns a 16 character base32 secret. Compatible with Google Authenticator

Google Authenticator Compatible

The library works with the Google Authenticator iPhone and Android app, and also includes the ability to generate provisioning URI's for use with the QR Code scanner built into the app:

totp.provisioning_uri("alice@google.com") # => 'otpauth://totp/alice@google.com?secret=JBSWY3DPEHPK3PXP'
hotp.provisioning_uri("alice@google.com", 0) # => 'otpauth://hotp/alice@google.com?secret=JBSWY3DPEHPK3PXP&counter=0'

This can then be rendered as a QR Code which can then be scanned and added to the users list of OTP credentials.

Working example

Scan the following barcode with your phone, using Google Authenticator


Now run the following and compare the output:

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

Links

• Project home page (GitHub)
• Documentation (Read the Docs)
• 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