Surely you would have to store something off-chain in order for it to be inaccessible until a given point in time. Unless you can predict the future, I'm not s

Surely you would have to store something off-chain in order for it to be inaccessible until a given point in time. Unless you can predict the future, I'm not sure how you would generate a key that would be unknowable now but generally available in the future.