Understanding Double Spending

One of the different reasons blockchain and crypto didn't work until Bitcoin was introduced by Satoshi Nakomoto was because a user could alter the information on a distributed ledger to give themselves back any tokens they had spent. This is what is known as double-spending. Just imagine the possibility of making copies of a digital currency to undermine the integrity and security of the network of any crypto for illegal or unethical purposes.

So what exactly is Double-spending, well as hinted earlier, it is simply spending the same crypto or blockchain token more than once and since cryptocurrencies are tokens that show the value of a blockchain or distributed ledger, therefore without putting proper mechanisms in place, it would be easy to change a ledger entry and give yourself back the amount you had spent.

This weakness is unique to digital money systems and doesn't affect physical money or currencies, because you can't spend the same currency note or coin twice, once you buy something with it, the seller would give you what you bought and there is no way you are getting that note back except you decide not to continue with the transaction, but you must return the goods in exchange for your physical note or coin.

To solve this fundamental flaw in digital money, third-party auditors are usually involved in verifying transactions and sums between parties and organisations, but unfortunately, we humans have trust issues. Sometimes, auditors can not be trusted to do this especially if bad players are bent on scamming and cheating, even auditors can be bribed, so this therefore begs the need for decentralisation and this is exactly the problem the blockchain solves because the blockchain is a distributed ledger of transactions and it is immutable, but how did Nakomoto solve the double spending problem so much so that we hardly experience it nowadays?

Preventing Double Spending:

The solution presented by Satoshi Nakamoto, involved timestamping transactions and chaining them together using cryptography. Wondering what cryptography is right? well, it is simply encrypting transactions, maybe you should stay tuned for my next article here on spur protocol because we are going to discuss that next, but now, let's continue.

This chaining process and encryption of transaction would work if it is a large and fast distributed network like those of Bitcoin and Ethereum, besides, you should still be very careful not to fall prey to this attack though.

Now, let's look deeper into how this problem is solved. Nodes are key players in preventing double spending attacks, if you are wondering what nodes are,then you will need to check my previous article on what nodes are, but in the meantime, see nodes as computer systems that are connected to a blockchain for certain purposes 

How Nodes Prevent Double-Spending:

Transaction Validation:

When a node receives a new transaction, it checks the transaction history of the sender to ensure that the sender has sufficient funds and that those funds have not been spent already.

The process involves examining the blockchain ledger to verify that the sender's previous transactions are valid and that the funds being spent have not been spent at all.

Consensus Mechanism:

The consensus mechanism is the process by which the network agrees on the order of transactions.This is important for preventing double-spending attacks because it establishes a single, definitive history of transactions.Nodes that participate in the consensus mechanism would always agree on which transactions are valid and which are not.

Blockchain Immutability:

The immutability of the blockchain, meaning that once a transaction is recorded, it cannot be altered, is another key factor in preventing double-spending. Once a transaction is contained within a block, and that block is added to the chain or chained, it is very difficult to alter. This becomes a problem for anyone who intends to alter the transaction.

Node's Role:

Basically,each node that validates transactions, checks the history of each coin that is being sent. If a coin has a record that it has been spent already, then the node will reject the new transaction.

Let's draw the curtains here, we are going to look at the different double spending attacks in crypto and cryptography next, thanks for reading. I will be in the comments incase you have any questions.