[Feature request] Time period based signed message delivery on keybase

• System:
  A message is sent for the recipient to view after a certain time frame, the recipient must be able to view the message only after the time frame has elapsed.

• Setup:
  Authentication of users is already done and each message is signed already.

The message is sent via a session key that's generated using both sender and receiver's public keys along with a relative time difference as inputs
Upon receiving the message, the recipient must not be able to view the message until sender rekeys or until definite time is obtained.

• Question:
  How can we establish a concept of time in a cryptographic system ?
  Given identities are independently defined, the concept of relative time is defined by the time on their systems, unless there's a workaround.

Happy to hear more thoughts on this.
Cheers!

References:

• One time password

The issue names no files, tests, or entry points. Start by reviewing the signed-message and session-key design described here, along with the linked one-time-password reference, and clarify how time should be established between independently defined identities. Done would require an agreed protocol and implementation scope, not just a code change.