TOTP (Time-based One-Time Password) as I understand is an algorithm that uses the current time as a variable along with a shared key to generate a secured token. Wiki page for reference: http://en.wikipedia.org/wiki/Time-based_One-time_Password_Algorithm
What I wanted to know is whether it is possible to determine the timestamp data (time + timezone) from a particular TOTP value? I can generate the shared key which was used to generate the TOTP value.
The problem I'm facing is that we make use of TOTP to perform validations between our offline Android/iOS clients and our server. However, once in a while we encounter a user whose TOTP tokens fail to authenticate. We ask them the same sundry questions about current time synchronisation and to check their timezone. Often times, users have a hard time determining even this.
So, I was wondering whether I could simply work out the timestamp + tz information myself from the faltering TOTP token, provided I have access to the shared key used to generate the said TOTP token.
Thanks for reading and any help would be greatly appreciated.