Differences in delta number

Question

Differences in delta number

SirPhemmiey opened this issue 5 years ago · comments

Oluwafemi Akinde commented 5 years ago

Hi guys. You guys have done a great job.

I am just curious. I want to know the meaning behind the delta numbers.

Sometimes i see, -4, -1, 0. What do they all mean? Are there more delta numbers?

Jeremy Scalpello · Answer 1 · Tue Oct 01 2019 02:12:03 GMT+0800 (China Standard Time)

Hey! Thanks for using the library :)

The delta describes how many time slots away the entered code was from the current time-based code.

So for example, if the delta is 0, then the user's code matches the current code which would be generated with the current time. A delta value of -2 means the user's code would have been generated 2 slots (I.E 60 seconds) in the past. A positive value would indicate the user's code is from the future.

This was done to prevent a little time drift on the user's device or data entry delay (I.E while the user types the code after reading it from their device) from disrupting the authentication flow.

Does that make sense?

Oluwafemi Akinde · Answer 2 · Tue Oct 01 2019 02:31:48 GMT+0800 (China Standard Time)

Great! I now understand.

Thanks.

A positive value would indicate the user's code is from the future

BTW, that got me chuckled. :)