java - Concept for OTP with Time limit -

programme a:

hash(username, password , nowtime())

*nowtime() defined as:

calendar cal = calendar.getinstance(); cal.gettime()

programme b:

hash(username, password , nowtime())

*programme b loop (up 15 sec) , each nowtime() defined as:

calendar cal = calendar.getinstance(); cal.add(calendar.second, -1);

though time both programme matches, otp produced same hash function different. not need code, please me understand sync time between 2 programme.

calendar.gettime() returns time resolution of 1 milli second. therefore milli second values surely different on both computers (or same pure luck).

to go solution have set milli seconds 0 before processing

cal.set(calendar.millisecond, 0);

then should have @ least 1 match.

Live