FreeOTP: TOTP - enhancement proposal

[Juergen Kammer]

Hi,

for TOTP tokens, would it be possible to add a timeoffset 
in seconds?

If you have a hardware token and know the seed of it, you
could then use FreeOTP and the hardware token in parallel.

Hardware token clocks tend to be faster or slower than
the current time, and servers checking the values usually
keep track of the offset a token has (usually the offset slowly
increases or decreases), and they accept a value only in a small
time window (i.e. 2 minutes plus or minus).

If the hardware token in that situation has accumulated an offset
of 4 minutes, FreeOTP values are these 4 minutes off from the value
which the server checking the value expects -
in one direction, you'd have to wait for 4 minutes until you could
use the FreeOTP value -- in the other direction you are out of luck
(the value checked for is 4 minutes "in the future").

A configurable offset would be the easiest way to help there.
Adjusting the time of the device FreeOTP runs on to the time the
hardware token internally uses is no real alternative ;-).

Best regards,
    Juergen.