Package: pyotp
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 inRFC 4226(HOTP: An HMAC-Based One-Time
Password Algorithm) and inRFC 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 useGoogle
Authenticator,Authy, or another
compatible app. Users can set up auth tokens in their apps easily by using their phone camera to scanotpauth://QR codes provided by PyOTP.Implementers should read and follow theHOTP security requirementsandTOTP security considerationssections of the relevant RFCs. At
minimum, application implementers should follow this checklist:Ensure transport confidentiality by using HTTPSEnsure HOTP/TOTP secret confidentiality by storing secrets in a controlled access databaseDeny 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 (rate limit) brute-force attacks against your application’s login functionality (see RFC 4226, section 7.3)When implementing a “greenfield” application, consider supportingFIDO U2F/WebAuthnin
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 theOWASP Authentication Cheat SheetandNIST SP 800-63-3: Digital Authentication Guidelinefor a high level overview of
authentication best practices.Quick overview of using One Time Passwords on your phoneOTPs involve a shared secret, stored both on the phone and the serverOTPs can be generated on a phone without internet connectivityOTPs 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
CodeInstallationpip install pyotpUsageTime-based OTPsimport pyotp
import time

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

# OTP verified for current time
totp.verify('492039') # => True
time.sleep(30)
totp.verify('492039') # => FalseCounter-based OTPsimport pyotp

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) # => FalseGenerating a Secret KeyA helper function is provided to generate a 32-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 40-character hex-encoded secretGoogle Authenticator CompatiblePyOTP 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, usinghttps://github.com/soldair/node-qrcode) 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 exampleScan the following barcode with your phone’s OTP app (e.g. Google Authenticator):Now run the following and compare the output:import pyotp
totp = pyotp.TOTP("JBSWY3DPEHPK3PXP")
print("Current OTP:", totp.now())Third-party contributionsThe following third-party contributions are not described by a standard, not officially supported, and provided for
reference only:pyotp.contrib.Steam(): An implementation of Steam TOTP. Uses the same API aspyotp.TOTP().LinksProject home page (GitHub)DocumentationPackage distribution (PyPI)Change logRFC 4226: HOTP: An HMAC-Based One-Time PasswordRFC 6238: TOTP: Time-Based One-Time Password AlgorithmROTP- Original Ruby OTP library byMark PercivalOTPHP- PHP port of ROTP byLe LagOWASP Authentication Cheat SheetNIST SP 800-63-3: Digital Authentication GuidelineFor new applications:WebAuthnPyWARPVersioningThis package follows theSemantic Versioning 2.0.0standard. To control changes, it is
recommended that application developers pin the package version and manage it usingpip-toolsor similar. For library developers, pinning the major version is
recommended.