totp.rb

#!/usr/bin/env ruby

require 'rotp'
require 'uri'
require 'cgi'

otpuri = STDIN.readline
otpuri = URI(otpuri)

if otpuri.scheme != "otpauth"
	raise "invalid uri scheme"
end

if otpuri.host != "totp"
	raise "invalid uri host '#{otpuri.host}' (only TOTP supported)"
end

opts = CGI::parse(otpuri.query)

def getopt(opts, name, default)
	opt = opts[name]
	return default if !opt || opt.length != 1
	return opt[0]
end

totp = ROTP::TOTP.new(opts['secret'][0], interval: getopt(opts, 'period', '30').to_i, digits: getopt(opts, 'digits', '6').to_i)

puts totp.now