Verifiable PDFs (or vPDFs) is the open-source technology that Block.co leverages. VPDFs allow anyone to ensure that a PDF’s integrity is secured by anchoring a hash of that PDF on a public blockchain. Since public blockchains are decentralized and immutable the hash will be tamperproof. Thus, it can be trusted that it was never modified, which allows anyone with the PDF to validate the document by consulting directly with the blockchain (and not necessarily the entity that created the PDF). In addition, we make sure that the identity of the person that created and anchored the PDF document can be validated in a decentralized way by consulting several public online resources that the entity controls.