One-Time Passwords (OTP) - Example
In this section, we shall provide an example of how to generate and validate One-Time Passwords (OTP) in Python. The Python library of our choice is PyOTP, which implement the RFC 4226 and RFC 6238 standards. If you want to use this library you should follow the requirements in those standards. Installation:
pip install pyotp
We need to create a base32 secret which has to be shared between the authentication server and the client. We will use Google Authenticator OpenSource OTP model which produce a URI for an exchange, the secret and additional client-server details. It includes the shared secret, the client's username, and the issuer's name.
import pyotp
base32secret = pyotp.random_base32()
print('Secret:', base32secret)
totp_uri = pyotp.totp.TOTP(base32secret).provisioning_uri(
issuer_name="Secure App")
print(totp_uri)
Sample output:
Secret: S3K3TPI5MYA2M67V
otpauth://totp/Secure%20App:alice%40google.com?secret=S3K3TPI5MYA2M67V&issuer=Secure%20App
Once the client stores the secret in a secure way, in a time-interval of a 30 seconds (by default) a new code will be generated.
import pyotp
import time
base32secret = 'S3K3TPI5MYA2M67V'
print('Secret:', base32secret)
totp = pyotp.TOTP(base32secret)
print('OTP code:', totp.now())
time.sleep(30)
print('OTP code:', totp.now())
Sample output:
Secret: S3K3TPI5MYA2M67V
OTP code: 339838
OTP code: 284911
OTP Auth
Example validation check:
import pyotp
base32secret = 'S3K3TPI5MYA2M67V'
print('Secret:', base32secret)
totp = pyotp.TOTP(base32secret)
your_code = '123456'
print(totp.verify('Code Valid:', your_code))
Output:
Secret: S3K3TPI5MYA2M67V
Code Valid: True
Last modified 1yr ago