Proof of Ownership

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Proof of Ownership is a method that uses Bitcoin's decentralized ledger (also called blockchain) or Bitcoin-related technologies to track the different owners of a certain information over the time.

This technique can be used by artists or businesses to certify the integrity, date of publication and ownership of their creations or contracts.


Using the Bitcoin blockchain

The Bitcoin Core protocol now accepts raw data transactions up to 40 bytes per output using the opcode OP_RETURN. Putting the hash of the signature of a file's hash in the blockchain makes the owner of the private key associated with the signature the owner of the file in the blockchain (as long as someone else doesn't show up with a proof certified before).

Using a new blockchain

It's also possible to create a new blockchain for this purpose. This blockchain wouldn't only store coins but also notarized proofs.

Content of a proof


Only the people with the private key associated with the signature can prove they are the owner.


A Proof of Ownership is always attached to a piece of data. Certifying the ownership of a certain information in the blockchain also proves that this information existed at a certain time.


A Proof of Ownership is always attached to a piece of data using cryptographic functions. This makes it impossible to alter the data after certification. If the content is modified, even by a single bit, then the whole certificate becomes invalid.


Because proofs are logged in the blockchain, it makes it easy to make transfers of ownership and find the original issuer of a certificate. Certificates can’t be “double-spent”.


  • - Decentralized Proof of Ownership using Bitcoin's blockchain
  • - Certify your files and ideas for free in the Bitcoin blockchain
  • - list of metadata recently embedded in the bitcoin blockchain using OP_RETURN outputs.
  • Creating OP_RETURN transactions in the blockchain