What is Proof of Existence?

A service to anonymously and securely store an online distributed proof of existence for any document/file. Your documents are not stored in our database or in the blockchains, so you don't have to worry about your data being accessed by others.

What is stored is a cryptographic digest of the file, linked to the time in which you submitted the document. In this way, you can later certify that the data existed at that time. This is the first online service allowing you to publicly prove that you have certain information without revealing the data or yourself, with a decentralized certification based on the blockchains network.

The key advantages are anonymity, privacy, and getting a decentralized proof which can't be erased or modified by anyone (third parties or governments). Your document's existence is permanently validated by the blockchain even if this site is compromised or down, so you don't depend or need to trust any central authority. All previous data timestamping solutions lack this freedom.

Technical foundations

The document is certified via embedding its SHA256 digest in the blockchains. Once the transaction is confirmed, the document is permanently certified and proven to exist at least as early as the time the transaction was confirmed. If the document hadn't existed at the time the transaction entered the blockchain, it would have been impossible to embed its digest in the transaction (This is because of the hash function's property of being second pre-image resistant). Embedding some hash and then adapting a future document to match the hash is also impossible (due to the pre-image resistance of hash functions). This is why once the blockchain confirms the transaction generated for the document, its existence is proven, permanently, with no trust required.