Question

Based on current date and time, can i generate 6 digit number? One person said me to use timestamp. Please guide me how to generate 6 digit number based on current time stamp. I need to generate this in such way later I can check the number was generate before 5 second or not. I need to know what logic should I use to reverse logic to find out when the number was generated. Please help with sample code.

Which crypto technique i can use to generate digit if i input current date like DateTime.Now.ToString("yyyyMMddHHmmssffff") ?.

Answer 1

You could do this:

public static int GetTimestamp()
{
    // 10m ticks in a second, so 50m in 5 seconds
    const int ticksIn5Seconds = 50000000;
    return (int)((DateTime.Now.Ticks / ticksIn5Seconds) % 1000000);
}

This gets a number with one to six digits, which changes every five seconds.

Edit:

If course, this is not cryptographically secure: if you observe one number then you know what later ones are going to be (because they just increase by 1 each time). If unpredictability is a requirement, you need a different approach.