Proof of Publication defines a protocol for timestamping and proving ownership of digital information in a distributed network.
There are many problems with the methods implemented by existing notary services. You can find them here.
The Proof of Publication approach abandons the unscalable, expensive 1:1 relationship between documents and transactions.
Proof of Publication defines a protocol based on a merkle tree. The client process hashes documents and adds each hash as a leaf in a merkle tree. The program publishes the merkle tree root to the block chain, saving the original data of the merkle tree in a local file.
The cost of notarizing one document is the same as the cost of notarizing N documents. These savings are transferred to the user, or paid towards miners for a higher priority transaction.
Providers offer a Proof of Publication web service. Each Proof of Publication web service is known as a Provider. Providers should store original merkle tree data for users and handle the heavy-lifting, and ideally display a simple and easy to use interface. Providers fill a need in the market for "quick and easy" notary services, eliminating learning and setup times by acting as trusted service providers.
Authentication of documents via digital signature is possible within this protocol. Publishers store the merkle root of all hashed documents and a signature (proving authenticity) on the block chain. Publishers lump all unauthenticated data together in a single merkle tree to save time, space, and money.
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