Blockchain – A ledger

Blockchain is the technology behind bitcoin, however there’s growing awareness around the fact that it has an immense unexplored potential. It is essentially a public, non (easily) counterfeitable ledger, and just as it works for digital currencies, it could work to record any other transactions.

Have a cow you want to sell? Make a digital ID for the cow (name, colour, weight… whatever information is relevant). Make an md5, then butcher it in fourth and make an ID for each quarter that links to the original cow’s ID, then split it into smaller pieces down to your own steak at the supermarket. Each steak with it’s own ID that is the last leaf of a blockchain rooted to the original cow’s ID.
You will know exactly where it comes from, what farmer, how old it was, etc.

Want to buy a pair of jeans but don’t know if they are ethically sustainable? get a blockchain for the jeans linking to other blockchains for where the fabric was made, which country, what are the workers’ conditions, etc.

If you are interested in the technicalities, let’s consider the following chain of digital data blocks:

<abcde ; 0 ; 15> 
<aaabb ; 15 ; 22>
<ddd ; 22 ; 34>
<a ; 34 ; 35>
<ccccd ; 35 ; 51>

(we assume a=1, b=2, c=3, etc…     so:  a+b+c+d+e = 15)

This can be seen as a very elementary blockchain where each block contains:

  • the actual data,
  • metadata (data that describes the actual data) containing a “checksum” of the previous block, and
  • metadata containing the new checksum.

In this case the checksum is simply the sum of the values of each letter in the message, plus the previous block’s checksum. What’s important is that I could never add and validate a block that conflicts with the data on previously published blocks.
In short, the validation of each new block added to the chain makes the whole pre-existing chain immutable.
For example if I were to add a new block such as one of the following two:

<kkkkk ; 51 ; 57> (11 + 11 + 11 + 11 + 11 +51 ≠ 59)
or
<abcde ; 44 ; 59> (no previous block had checksum 44)

we would immediately know that something is wrong with it, and we would not validate it as being part of the chain.

Back to our cow example, if you wanted to sell a steak pretending that the cow was a young brown female, while it was in fact a young brown male, the checksum of the newly added block would reveal that immediately.

The system is not impossible to counterfeit, but it is a huge step ahead compared with the trackability systems we have in place today… where does your steak come from? what is your jeans’ fabric weight per square meter? who picked your coffee beans and how much were they paid for it?

Having public ledgers for transactions would also be a huge step towards an open society that makes commensurate efforts to protect both privacy and security. The current Big Brother model works but is inefficient, while blockchain is one among many technologies that could help direct our effort towards larger and most relevant events, transactions, and people, in order to attain a more transparency, socially secure and just society. 

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