Guaranteed decryption time schedule Suppose you want to store information in, say, safe container for  a certain time, after which you want information to be accessible.

Let's assume simple idea and fill details by yourself. Take some space of strings (for example 10 characters in size, containing capital and ordinary letters) and encrypt a container with randomly generated password that is never stored - for example by asking other person to type the password without revealing it, or by closing your eyes and enter random characters).

Then start breaking by brute force. It doesn't guarantee perfect timing, but in the average You may estimate how long it would take to break the password and open stored content. By clever manipulation of string's space [ed: of the password] you may probably scale it from seconds to epochs.

You may assume some cascade/ hierarchy system: simple random input ( say: 3 chars of low dimensional space) is used as a seed for cascade of the systems you have to break. As breaking password from 3 char space is deterministic in fraction of seconds, such cascade may give you a loosely speaking, a way of measuring a time range of second with not so big error. So cascade of such cryptography systems may work as a clock, implemented on non safe scheduling system.

Questions:


Are there known any protocols or algorithms with precisely narrowed time estimate above?
Is it possible to design such brute force breaking scheme it guarantee that it will be successful after t_min but before t_max?


For given system working on isolated ( this one) problem it provides a method of measuring time without use of values from internal clock ( which is controlled by user, hackers etc). Using such multiple systems of cascades method we may in probabilistic way guarantee that box is open not earlier than certain amount of processor cycles is used. That's the goal of such idea.

Processor cycle count measurement by brute force breaking scheme :)
Are there known any protocols or algorithms with precisely narrowed time estimate above?


Of course not, because it would depend on the details of the system performing the brute forcing / dictionary attacks. Your comment: "Processor cycle count measurement by brute force breaking scheme" basically contains the answer.


  Is it possible to design such brute force breaking scheme it guarantee that it will be successful after t_min but before t_max?


Same answer of course, but you can certainly create a protocol which requires a certain proof-of-work. And that's precisely what the current block chain technology is all about. But proof-of-work relates to the amount of work performed, not the amount of time that it took.



You could of course also use a trusted third party to release information - such as a key - at a certain time. Not all protocols allow for such a third party to exist though.