Blockchain-based trusted timestamping can be a very useful tool for ensuring data integrity for many applications. Nevertheless, it is crucial to understand what it can prove and what it cannot prove. Timestamping can only prove that the timestamped data, such as a photo, a video, pdf, etc. already existed in or before the very moment it was timestamped.
What are potentially suitable use cases for trusted timestamping?
- Damage documentation - When you move into a new flat and want to document that a damage existed before you moved in. Similarly, it can be proven that a specific damage to a rental car existed before a certain point in time. This works very well in practice, especially with photos, as it is impossible to create all possible damage variants prophylactically, e.g. with Photoshop, and then timestamp them before the actual damage occurs.
- Dashcams - If you are using a dashcam that timestamps the video stream in real time, blockchain-based timestamping also makes sense. If an accident happens, it can be proven that the recording was made at the time of the accident and not days or weeks later. This way, accusations of tampering with the recording can be countered.
- Knowledge documentation - Trusted timestamping can also be used to provide evidence that some knowledge existed at or before a certain point in time. It is important that the knowledge is special so that not all possible cases can be timestamped in advance. E.g. it would not be possible to secure with trusted timestamping the knowledge who will win the soccer world cup, because there is only a very limited number of participating nations. On the other hand, it would be possible, for example, to secure a forecast of a temperature curve with many thousands of data points as a forecast. Due to the large number of data points, there are almost infinitely many different temperature curves, so that a timestamp for a certain temperature curve has a high significance.
Blockchain-based timestamping can also be used to create a so-called "Proof of Authorship". However, just having a timestamp of an idea doesn't automatically prove authorship. It is important that not only the idea, but also the identity of the author are jointly documented in the timestamped document.
But even then it is conceivable that not the author was documented together with his idea, but a third person: If person A tells person B about an idea, person B could still timestamp the idea and claim it was their idea. Therefore, we recommend not to share an idea without timestamping it first.
Nevertheless, a tamper-proof document that documents the connection between an author and his idea at a certain point in time can be a very valuable piece of evidence, as a court ruling of the Hangzhou Internet Court shows.
Furthermore, a document that has a valid timestamp does not necessarily have to be free of manipulation. For example, a photo may have been changed after it was taken and then anchored in a public Blockchain to create a valid timestamp. However, it is true that a photo that has a valid timestamp has not been changed since the time of the creation of the timestamp, as any change would render the timestamp invalid.
Finally, there is no definite answer to the question of whether a timestamp would be accepted in court. In the past, we have seen cases when blockchain-based timestamping was accepted as part of a proof. But this does not automatically imply that every court will accept blockchain-based timestamps as this is usually up to the judge.