Subject: Re: [bitcoin-dev] Why OpenTimestamps does not "linearize" its transactions

From: Bryan Bishop <[email-masked]>
Date: Tue, 14 Jun 2022 08:55:55 -0500

On Tue, Jun 14, 2022 at 8:48 AM Undiscussed Horrific Abuse, One Victim of
Many via bitcoin-dev <[email-masked]> wrote:

> OTS needlessly adds the requirement that the user publicize their .ots
> files to everybody who will make use of the timestamp.

Publication is not a component of the OTS system.

This does not provide the service you describe. It would be trivial to
> include enough cryptographic information in the original OP_RETURN, so
> as to obviate the need for publicizing the .ots file.
>

(Why would it be needless to require everyone to publish OTS files but not
needless to require everyone to publish via OP_RETURN? In fact, now you
have blockchain users that don't ever use your OP_RETURN data.)

> If I send my .ots file to another party, a 4th party can replace it
> with their own, because there is no cryptographic pinning ensuring its
> contents. This changes the timestamp to one later, no longer proving
> the earliness of the data.
>

You can't replace a timestamp in the OTS system; you can only make a new
timestamp. To use the earlier timestamp, you would have to use the earlier
timestamp. At any time it is allowed to make a new timestamp based on the
current clock. The use case for OTS is proving document existence as of a
certain time and that if you had doctored a file then said doctoring was no
later than the earliest timestamp that can be provided.

I was just talking about this the other day actually...
https://news.ycombinator.com/item?id=31640752

- Bryan
https://twitter.com/kanzure