How can a collective awareness platform for missing children be related to a revolutionary crypto currency technology? Or is it that blockchain can have other potential uses besides creating and controlling digital coins? Let us start with an explanation of what blockchain actually is, besides being a buzzword. How do blockchains work, what problems do they solve and how can they be used?

In simple terms a blockchain, like the name indicates, is a chain of blocks that contains information. The technique was first described in 1991 by a group of researchers and was originally intended to substitute the work of a notary, i.e. to timestamp digital documents so that it’s not possible to backdate them or to tamper with them. This idea never flourished, until it was adapted by Satoshi Nakamoto in 2009 to create the digital cryptocurrency Bitcoin.

Today, a blockchain is considered to be a distributed, decentralized and public digital ledger that sits on top of the internet and is completely open to anyone. Like a spreadsheet that is duplicated thousands of times across a network of public computers. It also carries an interesting property: once some data has been recorded inside a blockchain, it becomes very difficult, practically impossible, to change it.

So, how does that work? Well, let’s take a closer look at a block. Each block contains three main elements: some data, the cryptographic identifier of the block (called hash) as well as the hash of the previous block.

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The data that is stored inside a block depends on the type of blockchain. The Bitcoin blockchain for example stores the details about a transaction, such as the buyer, the seller and the amount of coins. The hash value, on the other hand, uniquely identifies a block AND all of its contents. You can think of a hash as a fingerprint. But it is actually, produced by a hash function, that “describes”, or better, maps the block’s data (which is of arbitrary size) into a single value of fixed size. The third element inside each block is the hash of the previous block. This effectively creates the chain of blocks and it is this technique that makes a blockchain so secure.

Once a block is created, its hash is calculated. Changing something inside the block will cause the hash to change too. In other words, hashes are very useful when you want to detect changes to blocks. If the fingerprint of a block changes, it no longer is the same block.  So, changing a single block will make all following blocks invalid.

But using hashes is not enough to prevent tampering. Computers these days are very fast and can calculate hundreds of thousands of hashes per second. You could effectively tamper with a block and recalculate all the hashes of other blocks to make your blockchain valid again. To mitigate this, blockchains have something called proof-of-work. It’s a mechanism that slows down the creation of new blocks. But there is one more way that blockchains secure themselves and that’s by being distributed.

Image Courtesy of Blockgeeks

Instead of using a central entity to manage the chain, blockchains use a peer-to-peer network and anyone is allowed to join and get a full copy of the blockchain. Furthermore, every network node has the right to verify any new block and make sure it is intact. If everything checks out, each node adds this block to their own blockchain. All the nodes in this network create a consensus. They agree about what blocks are valid and which aren’t using the majority vote (>50% of the nodes).

So to successfully tamper with a blockchain you’ll need to tamper with all blocks on the chain, redo the proof-of-work for each block and take control of more than 50% of the peer-to-peer network. Only then will your tampered block become accepted by everyone else. This is almost impossible to do.

Fore more detailed information, you may watch the following explanatory video:

The invention of blockchain technology peaked the tech community’s interest, and soon, blockchain evolved to something greater; To quote Don & Alex Tapscott, authors of the Blockchain Revolution, “the blockchain is an incorruptible digital ledger that can be programmed to record not just financial transactions but virtually everything of value”.  Storing medical records, digital contracts or even collected taxes, are only some examples. In short, according to the Harvard Business Review, blockchain is not another disruptive technology, but a foundational one that could eventually reshape global economy, and, as a consequence, it could transform modern social structures.

But how can blockchain help ChildRescue?
A core objective of ChildRescue is to enhance the investigation process for a missing child by “activating” its Social Sensors. Social Sensors are citizens who are located in specific geographic areas, proximate to the point that the missing child was last seen, and can use the ChildRescue mobile app to send information related to the case. This information could be a testimonial, a photo, or any other clue that could assist in the investigation.

Since such potential evidence could prove crucial in the identification and finding of a child (but also to prevent malevolent use), the ChildRescue platform plans to record all incoming evidence submissions in a secure and incorruptible digital ledger, implemented with the blockchain technology. In this way, trust and verifiability is added to the platform, while the consistency of reported information is preserved.

It should be made clear, however, that the raw pieces of evidence or any personal data should not be recorded in the blockchain, due to data privacy issues. ChildRescue will tread cautiously and safely on the data protection path, having already conducted a thorough study on related national and European laws and regulations and having established an Ethics Advisory Board (EAB)  to ensure that the ChildRescue solution will respect data privacy and protect personal data.  Due to the same reason, whether blockchain will be used in other parts of the project, or not, is currently a matter to be further discussed.

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Credits to WorldSpectrum