- It is not owned by a single entity, hence it is decentralized
- The data is cryptographically stored inside the blockchain is immutable, so no one can tamper with the data that is inside the blockchain
- The blockchain is transparent so one can track the data if they want to
One of the most interesting and misunderstood concepts in blockchain technology is “transparency.” Some people say that blockchain gives you privacy while some say that it is transparent. Why do you think that happens?
Well… a person’s identity is hidden via complex cryptography and represented only by their public address. So, if you were to look up a person’s transaction history, you will not see “Bob sent 1 BTC” instead you will see;
“1MF1bhsFLkBzzz9vpFYEmvwT2TbyCt7NZJ sent 1 BTC”
So, while the person’s real identity is secure, you will still see all the transactions that were done by their public address. This level of transparency has never existed before within a financial system. It adds that extra, and much needed, level of accountability which is required by some of these biggest institutions.
Speaking purely from the point of view of cryptocurrency, if you know the public address of one of these big companies, you can simply pop it in an explorer and look at all the transactions that they have engaged in. This forces them to be honest, something that they have never had to deal with before.
However, that’s not the best use-case. We are pretty sure that most of these companies won’t transact using cryptocurrencies, and even if they do, they won’t do ALL their transactions using cryptocurrencies. However, what if the blockchain technology was integrated…say in their supply chain?
You can see why something like this can be very helpful for the finance industry right?
Immutability, in the context of the blockchain, means that once something has been entered into the blockchain, it cannot be tampered with.
Can you imagine how valuable this will be for financial institutes?
Imagine how many embezzlement cases can be nipped in the bud if people know that they can’t “work the books” and fiddle around with company accounts.
The reason why the blockchain gets this property is that of the cryptographic hash function.
In simple terms, hashing means taking an input string of any length and giving out an output of a fixed length. In the context of cryptocurrencies like bitcoin, the transactions are taken as input and run through a hashing algorithm (Bitcoin uses SHA-256) which gives an output of a fixed length.
Let’s see how the hashing process works. We are going to put in certain inputs. For this exercise, we are going to use the SHA-256 (Secure Hashing Algorithm 256).
In the case of SHA-256, no matter how big or small your input is, the output will always have a fixed 256-bits length. This becomes critical when you are dealing with a huge amount of data and transactions. So basically, instead of remembering the input data which could be huge, you can just remember the hash and keep track.
A cryptographic hash function is a special class of hash functions that has various properties making it ideal for cryptography. There are certain properties that a cryptographic hash function needs to have in order to be considered secure. You can read about those in detail in our guide on hashing.
There is just one property that we want you to focus on today. It is called the “Avalanche Effect.”
What does that mean?
Even if you make a small change in your input, the changes that will be reflected in the hash will be huge. Let’s test it out using SHA-256:
Do you see that? Even though you just changed the case of the first alphabet of the input, look at how much that has affected the output hash. Now, let’s go back to our previous point when we were looking at blockchain architecture. What we said was:
The blockchain is a linked list that contains data and a hash pointer that points to its previous block, hence creating the chain. What is a hash pointer? A hash pointer is similar to a pointer, but instead of just containing the address of the previous block it also contains the hash of the data inside the previous block.
This one small tweak is what makes blockchains so amazingly reliable and trailblazing.
Imagine this for a second, a hacker attacks block 3 and tries to change the data. Because of the properties of hash functions, a slight change in data will change the hash drastically. This means that any slight changes made in block 3, will change the hash which is stored in block 2, now that in turn will change the data and the hash of block 2 which will result in changes in block 1 and so on and so forth. This will completely change the chain, which is impossible. This is exactly how blockchains attain immutability.
Culled from the Internet.