21Oca
Simple certified time format
I have an application where a device needs a signed message "UTC date&time at time of signature", signed by an authority that it trusts. This is simpler than an RFC 3161 timestamp, which is made on request and includes a request ID has provision for a nonce, allowing a challenge/response protocol.
Note: I realize that therefore, a signed message with an old UTC date&time can be replayed. That's not an issue for e.g. a safe programmed to open only past a certain date
Is there a standard/common format for that?
Is there a standard/common attribute to the certificate of a Certification Authority indicating that this CA is trusted to emit signatures for that purpose? And what is such attribute for a standard timestamping authority ?
