Blockchain, an emerging digital proof system

A Blockchain is a continuously growing list of records, called blocks, which are linked and secured using cryptography (definition from Wikipedia). Blockchain is a set of technology and mechanisms to ensure that transactions are logged and reliable.

But if we move away from the technical details of the Blockchain technologies, we can consider Blockchain at a more conceptual level. A Blockchain is a distributed, peer-to-peer data store (called the ledger) where all transactions between participants are captured. Information logged in a Blockchain is verified by consensus, and can never be modified or erased.

The Blockchain is immutable and blocks can only be added to the end of the chain (append-only). This means that different stakeholders can access a list of ordered events anytime. It is guaranteed by the underlying mechanisms of the Blockchain.

The other interesting aspect of a Blockchain is that it is secured by identification, authentication and authorization mechanisms. So a Blockchain is not only a consistent source of historical information, but it is also a source you can trust. Because of these properties, a Blockchain can be used as a proof system.

Proof of existence (or non-existence)

As the information in a Blockchain is never altered nor erased, you can access all blocks and find the one that proves that a transaction (or a digital event) happened in the past. In a similar way, you can check the Blockchain and if a transaction is not present, it means it never happened. A Blockchain is a single source of truth for participating parties.

Proof of time

Most of the time, proving that something happened may not be sufficient. Typical verification scenarios need to check when the event happened. As all transactions are logged with a timestamp, each block can be used to prove when a specific transaction occurred.

Proof of authoring

As mentioned before, a Blockchain relies on an advanced security mechanism (cryptography, digital ids, authorization). All blocks added to the ledger must be digitally signed. So at any point in time, the author of a block can be easily verified. In a business transaction scenario, it is then possible to identify the two parties involved (using authors of block n-1 and block n).

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With the immutability and security properties of a Blockchain, it is possible to identified WHAT happened, WHEN it happened, and WHO was involved in a digital event. You can then imagine a lot of scenarios to cover typical business needs (proof of transaction, proof of ownership, proof of digital payment, etc…).

Many different industries are considering Blockchain to provide digital proofs for audits or dispute resolutions. It is also mechanism to give evidence of something one claims without using an independent third party (organic products, fair trade, carbon footprint, etc…). If your customers don’t trust you, maybe they will trust the Blockchain.