Feature request: More robust timestamps

[jimstir]

Reference Issue: vacp2p/rfc#430
Author: oskarth

Discussed in vacp2p/rfc#397

^{Originally posted by bgits June 11, 2021}
Having reliable timestamps would be valuable for a wide range of applications. Even accuracy within a range of minutes from time of origination covers a wide range of applications. What research or proof of concepts already exists into how this could be implemented?

---

Currently we have receiver timestamp, and there's a WIP to get sender timestamp. See this PR: #417 and discussion here #219

In the future, having block height as a timestamp might be desirable for some applications.

What are more precise requirements and expectations here @bgits? cc @staheri14

---

There is the open timestamps project which uses blockchain based timestamps. Some use cases are outlined here: https://petertodd.org/2016/opentimestamps-announcement

In use cases like voting for now it's possible to handle requirements using block height and vote specific nonces.

The canonical use case is when chat dialogue is used for discussion in things like dispute resolution, the question of when something was said maybe germane to resolution.

[petertodd]

In the future, having block height as a timestamp might be desirable for some applications.

I think what you want here is a block hash. A simple height is just an integer that doesn't prove anything. A block hash is known to have been created at a specific point in time, and impossible to guess before that time, so inclusion of a hash proves the message was created after that point in time.

To prove a message was created prior to some point in time, you need a cryptographic timestamp. As you notice, OpenTimestamps is a good way to achieve that.