不确定 'if float(message) >= time.time():' 在代码中的作用

Question

import cryptocode
import time
import sys
#Function to verify that the key is valid:
def check_valid(key):
    message = cryptocode.decrypt(key, 'cryptocode is amazing')
    if message == False:
        #The key is incorrect!
        return False
    if float(message) >= time.time():
        return True
    else:
        #The key has expired!
        return False
userKeyInput = input("Please enter your product key.")
keyChecked = check_valid(userKeyInput)
if keyChecked == True:
    print("You are good to go!")
if keyChecked == False:
    print("You have either entered an invalid key or your time has expired. Sorry!")
    sys.exit()

in this code we're creating a simple "trial product key". we're letting the user use the product for 2 hours. The password we will be using is cryptocode is amazing.

but I'm not able to grasp the significance of this statement in this program: if float(message) >= time.time(): , and what it is actually doing here

Answer 1

It would be appear to be the case that if successfully decrypted (ie if 'cryptocode is amazing' was the correct password), then message (the content of key once decrypted) contains the time of expiration in float format. Hence, the line you're asking about converts it into float and compares it with the current time to check if it had already expired. (If the current time > expiration time, then the expiration time is in the past: the key had, indeed, already expired.)

In other words: there's an implicit assumption here that the key given to the user was the expiration time, encrypted.