One-Time Password Library
This library provides an implementation of HMAC-Based One-Time Password Algorithm (HOTP; RFC4226) and Time-Based One-Time Password Algorithm (HOTP; RFC6238).
Usage
To create new TOTP secret:
require "otp"
# Create a TOTP instance and new key
totp = OTP::TOTP.new
totp.new_secret # create random secret
p totp.password #=> "123456" (password for the current time)
# Inspect TOTP parameters
p totp.secret #=> "YVMR2G7N4OAXGKFC" (BASE32-formated HMAC key)
p totp.algorithm #=> "SHA1" (HMAC algorithm; default SHA1)
p totp.digits #=> 6 (number of password digits; default 6)
p totp.period #=> 30 (time step period in second; default 30)
p totp.time #=> nil (UNIX time by Time or Integer; nil for the current time)
# Format TOTP URI. Otpauth scheme URLs can be read by OTP::URI.parse.
totp.issuer = "My Company"
totp.accountname = "account@exaple.com"
p totp.to_uri #=> "otpauth://totp/My%20Company:account@exaple.com?secret=47JBA7ZWDDLNZJMX&issuer=My+Company"
To verify given TOTP password:
require "otp"
totp = OTP::TOTP.new
totp.secret = "YVMR2G7N4OAXGKFC"
p totp.verify("123456") #=> true/false (verify given passowrd)
You can use the last and post option parameters to verify several generations, including before and after the current password.
# verify passwords from last 2 generation to post 1 generation
p totp.verify("123456", last: 2, post: 1)
Related Information
TOTP and HOTP algorithm details can be referred at the following URLs.
- RFC4226 - HOTP: An HMAC-Based One-Time Password Algorithm
- RFC6238 - TOTP: Time-Based One-Time Password Algorithm
In the OTP URI format, the value of "secret" is encoded with BASE32 algorithm. The Format details are described in the document of Google Authenticator.