Blockchain: Blueprint for a New Economy

whole of society, using the blockchain to

prove the existence and exact contents of

any document or other digital asset at a

certain time. Further, the blockchain

attestation functionality of hashing-plus-

timestamping supports the idea of the

blockchain as a new class of information

technology.

Blockchain attestation services more

generally comprise all manner of

services related to document filing,

storage, and registry; notary services

(validation); and IP protection. As

articulated, these functions take

advantage of the blockchain’s ability to

use cryptographic hashes as a permanent

and public way to record and store

information, and also to find it later with

a block explorer and the blockchain

address pointer from the blockchain as a

universal central repository. The core

functionality is the ability to verify a

digital asset via a public general ledger.

There are several blockchain-based

attestation services in different stages of

development or proof of concept, such

as Proof of Existence, Virtual Notary,

Bitnotar, Chronobit, and Pavilion.io. The

specifics of how they might be different

or similar are emerging, and there is

presumably a lot of functionality

fungibility in that any of the services can

simply hash a generic file of any type.

The first and longest-standing service,

Proof of Existence, is described in detail

next.

Proof of Existence

One of the first services to offer

blockchain attestation is Proof of

Existence. People can use the web-

based service to hash things such as art

or software to prove authorship of the

works.99 Founder Manuel Aráoz had the

idea of proving a document’s integrity by

using a cryptographic hash, but the

problem was not knowing when the

document was created, until the

blockchain could add a trusted

timestamping mechanism. 100 Proof of

Existence demonstrates document

ownership without revealing the

information it contains, and it provides

proof that a document was authored at a

particular time. Figure 3-1 shows a

screenshot from the scrolling list of

newly registered digital assets with the

Proof of Existence service.

Figure 3-1. “Last documents registered”

digest from Proof of Existence

With this tool, the blockchain can be

used to prove the existence and exact

contents of a document or other digital

asset at a certain time (a revolutionary

capability). Providing timestamped data

in an unalterable state while maintaining

confidentiality is perfect for a wide

range of legal and civic applications.

Attorneys, clients, and public

administrators could use the Proof of

Existence blockchain functionality to

prove the existence of many documents

including wills, deeds, powers of

attorney, health care directives,

promissory notes, the satisfaction of a

promissory note, and so on without

disclosing the contents of the document.

With the blockchain timestamp feature,

users can prove that a document (like a

will) they will be presenting to a court

in the future is the same unaltered

document that was presented to the

blockchain at a prior point in time.

These kinds of attestation services can

be used for any kind of documents and

digital assets. Developers, for example,

can use the service to create unique

hashes for each version of code that they

create and later verify versions of their

code, inventors can prove they had an

idea at a certain time, and authors can

protect their works.

The proof-of-existence function works in

this way: first, you present your

document (or any file) to the service

website; you’re then prompted to “click

or drag and drop your document

here." The site does not upload or copy

the content of the document but instead

(on the client side) converts the contents

to a cryptographic digest or hash.

Algorithms create a digest, or a

cryptographic string that is

representative of a piece of data; the

digest created by a hash function is

based on the characteristics of a

document. No two digests are the same,

unless the data used to compute the

digests is the same. Thus, the hash

represents the exact contents of the

document presented. The cryptographic

hash of the document is inserted into a

transaction, and when the transaction is

mined into a block, the block timestamp

becomes the document’s timestamp, and

via the hash the document’s content has

essentially been encoded into the

blockchain. When the same document is

presented again, the same marker will be

created and therefore provide

verification that the documents are the

same. If, however, the document has

changed in any way, the new marker will

not match the previous marker. This is

how the system verifies the document. 101

One benefit of attestation services is

how efficiently they make use of the

blockchain. Original documents are not

stored on the blockchain, just their hash

is stored, which is accessible by private

key. Whenever a proof of existence

needs to be confirmed, if the recomputed

hash is the same as the original hash

registered in the blockchain, the

document can be verified as unchanged.

The hash does not need to (and cannot)