Blockchain Simplified: Understanding the Basics in Under 15 Minutes

Welcome back to my blog, where today we will be exploring the seemingly complex concept of blockchain. I want to show you that at its core, blockchain is actually a very simple data structure. While cryptocurrencies themselves may be complicated, it is important to recognize that blockchain is not the reason for their complexity. The true complexity lies in the consensus algorithm, mining, transactions, and everything else that surrounds blockchain. So, let’s begin by understanding the foundation of blockchain: hashes.

A hash is essentially a digital signature of any given data. It can be generated for a movie, an email, a word, or any other piece of data. Before we dive into actually building a blockchain, let’s take a moment to understand how hashes work. To do this, let’s consider two lists: List 1 which contains “ABC” and List 2 which also contains “ABC”. When we generate the digital signature or hash for each list, we find that the digital signatures are identical.

Now, let’s say I make a small amendment to List 2. When we generate the digital signature once again, we find that it is completely different from the previous one. This is crucial to understanding the foundation of a blockchain. A blockchain is essentially a chain of blocks, with each block containing the digital signature or hash of the previous block. The digital signature of the next block is based on the digital signature of the current block. Therefore, if any changes are made to a previous block, it will break the chain, resulting in completely different digital signatures for all subsequent blocks.

Let’s move on to actually coding our blockchain, using Java as our language of choice. Don’t worry, even if you’re not familiar with programming, I’ll make sure to explain the process in a way that is easy to understand. Our first step is to understand what constitutes a block. In our implementation, a block will consist of three key components: a list of transactions, the previous hash, and the current hash.

The list of transactions will represent the transactions that have taken place within that specific block. The previous hash will represent the digital signature or hash of the previous block, and the current hash will be based on both the transactions within the block and the previous hash. This relationship ensures the integrity of the blockchain, as any changes to previous blocks will result in different digital signatures for all subsequent blocks.

Let’s begin by creating a new class called “Block”. In this class, we will define the fields of our block, namely the previous hash, the list of transactions, and the current hash. Since we’re keeping things simple, we’ll represent the transactions as an array of strings. In a real-world blockchain, transactions would typically be represented as their own objects with additional properties, but for the purpose of this demonstration, we’ll keep it simple.

Now that we have defined our “Block” class, next we need to actually create the blockchain itself. We’ll accomplish this by using an ArrayList of blocks, as it provides flexibility and ease of use. So, let’s create our blockchain using the following code:

“`
ArrayList blockchain = new ArrayList();
Block genesisBlock = new Block(“”, new String[]{“Send 10 Bitcoins to Ivan”});
blockchain.add(genesisBlock);
“`

In the code above, we first create an ArrayList called “blockchain” that will hold our blocks. We then create the Genesis block, which is the first block in any blockchain. This block is special because it has no previous block to reference, so we leave the previous hash field empty. Additionally, we define the transactions within the block as a single string, indicating that 10 Bitcoins are being sent to Ivan.

Now that we have our Genesis block, we can begin building the rest of the blockchain. Each additional block will reference the previous block’s hash, ensuring the chain-like structure of the blockchain. While we won’t go into the details of adding more blocks here, the process involves calculating the hash of the transactions within each block and the previous hash.

In conclusion, blockchain may initially seem like a complex concept, but at its core, it is simply a chain of blocks where each block holds the digital signature or hash of the previous block. By understanding how hashes work and the relationship between blocks, we can begin to grasp the fundamentals of blockchain technology. While the implementation we discussed here is simplified for demonstration purposes, real-world blockchain systems involve much more complexity.

I hope this article has helped demystify blockchain and shed some light on its underlying simplicity. As always, feel free to leave your comments and questions below. Until next time!