I am writing a contract where I am storing the date/time using 'now' and performing date/time checks on those stored values.
My questions is how do you prevent date/time manipulation from miners?
If it cannot be prevented how do contracts even use date/time for critical checks?
nowis an alias forblock.timestamp. As such, this question should cover it: https://ethereum.stackexchange.com/questions/6795/is-block-timestamp-save-for-longer-time-periods – Richard Horrocks Jul 30 '16 at 19:39