[lmilcin]

It's not difficult to find examples:

https://twitter.com/gruber/status/991122089557004288?lang=en

There is even whole industry around the concept, it is called trusted timestamping: https://en.wikipedia.org/wiki/Trusted_timestamping

It basically works like this, you compute a hash of the document and send to some kind of service that will either publish your hash with the timestamp or will also sign the hash and the timestamp cryptographically without ever touching the document.

Later, you can refer somebody to the external service or let them examine the signature and the hash to prove that you were in possession of the information before certain date and time.

[JWett]

"Hash and Sign" timestamping is flawed in that it relies on the trust of a central authority. An insider with access to the private key could easily backdate a timestamp and sign any document/timestamp combination. Surety's widely-witnessed approach was meant to fix this issue.

Chaining the hash values made it fundamentally impossible for any malicious actor to generate a notary certificate for a future document that would roll up and produce the correct super hash value that is woven into the chain.