Blockchain is secured through various mechanisms that include advanced cryptography techniques, behavioral models and mathematical decision making. Blockchain technology is the structure behind most digital currency systems and is what prevents such digital currencies from being duplicated and destroyed.

The utility of blockchain technology is also being explored in other contexts where data immutability and security are valuable. Some examples include data recording and tracking charitable donations, medical databases, and supply chain management.

However, blockchain security is far from a simple matter. Therefore, it is very important to understand the basic concepts and mechanisms that provide strong protection to these innovative systems.

The concept of eternity and consensus

While there are many features that play a role in the security associated with blockchain, the two most important features are the concepts of consensus and immutability. Consensus refers to the ability of nodes in a distributed blockchain network to agree on the state of the network, and the validity of transactions. Generally, the process of reaching consensus relies on what is called a consensus algorithm.

On the other hand, Immutability, refers to the blockchain's ability to prevent changes to confirmed transactions. While these transactions often relate to the transfer of digital currency, they can also refer to other forms of digital data such as non-financial history.

Combined, consensus and immutability provide a framework for data security in blockchain networks. Although the consensus algorithm is what determines the rules of the system that must be followed, and all relevant participants must agree on the current state of the network - immutability ensures the integrity of the data and transaction history after each new block of data is confirmed for its validity.

The Role of Cryptography in Blockchain Security

Blockchains rely heavily on cryptography to ensure the security of their data. One of the cryptographic functions that is very important in this context is hashing. Hashing is a process where an algorithm known as a hash function receives an input data (any size) and produces a predetermined output that has a value with a definite length.

Regardless of the input size, the output will always have the same length. If the input changes, the output will change accordingly. However, if the input does not change, the hash result will always be the same - even if the hash function is performed several times.

In blockchain, the output value, known as a hash, is used as a unique identifier for a block of data. The hash of each resulting block is related to the hash of the previous block. Moreover, the hash block depends on the data contained in the block, meaning any changes that occur to that data will require changes to the hash block.

Therefore, the hash of each block is generated based on the data contained in that block and the hash of the previous block. These hash markers play an important role in ensuring the security and immutability of the blockchain.

Hashing also plays a role in the consensus algorithm used to validate transactions. For example, the Proof of Work (PoW) algorithm used in the Bitcoin blockchain to achieve consensus and mine new coins, uses a hash function called SHA-256. As the name suggests, SHA-256 takes input data and produces a hash that is 256 bits or 64 characters long.

Apart from providing protection for transaction history on the ledger, cryptography also plays a role in ensuring the security of wallets used to store digital currency. Public and private key pairs that allow users to receive and send payments are created through the use of public or 'asymmetric' key cryptography. The private key is used to create a digital signature for the transaction, and allows authentication of ownership of the coins sent.

Although there are many properties of asymmetric cryptography that are not covered in this article, however, this asymmetric cryptography prevents anyone outside the owner of the private key from accessing funds stored in a digital currency wallet, and secures the funds until the owner decides to use them (as long as the private key is not disclosed and compromised).

Cryptoeconomic

Moreover, apart from cryptography, a new concept known as cryptoeconomics also plays a role in maintaining the security of blockchain networks. It relates to a field of learning known as game theory. Which is a mathematical model of making rational decisions in situations where the rules and rewards have been determined. While traditional game theory can be applied to many uses, cryptoeconomics specifically models and describes the behavior of nodes in blockchain distributed systems.

Briefly, cryptoeconomics is an economic study within the scope of blockchain protocols and the possible outcomes of participant behavior. The security derived from cryptoeconomics is based on the idea that blockchain systems provide greater incentives for nodes to act honestly than to engage in malicious or wrongful behavior. Again, the Proof of Work consensus algorithm used in Bitcoin mining is a good example of this kind of incentive structure.

When Satoshi Nakamoto created the framework for Bitcoin mining, he intentionally designed it to be an expensive and resource-intensive process. Due to its complexity and computational demands, mining on the PoW algorithm involves a huge investment of money and time - regardless of where and who the mining node is. Therefore, such a structure provides a disadvantage for malicious activities and an advantage for honest mining activities. Dishonest or inefficient nodes will be quickly removed from the blockchain network, where honest and efficient miners have the potential to earn large block rewards.

Likewise, this balance of risk and reward also provides protection against potential attacks that could disrupt the consensus. This can be done by assigning the majority of the blockchain network's hash ratio to a group or entity. An attack like this, known as a 51% attack, can be extremely damaging if it is successfully carried out. Due to the high competitiveness of Proof of Work mining and the sheer size of the Bitcoin network, it is highly unlikely that someone with malicious intent will succeed in gaining control of a majority of the nodes.

Moreover, the cost of computing power required to gain 51% control of a giant blockchain network is astronomical, which is a direct disadvantage when comparing this enormous amount of investment with the relatively small potential reward. This contributes to a blockchain characteristic known as Byzantine Fault Tolerance (BFT), which is essentially the ability for a distributed system to continue working normally if some nodes are compromised or act incorrectly.

As long as the costs required to make the majority of nodes act maliciously are not profitable, and on the other hand provide greater incentives for nodes to act honestly, the system will be able to continue to develop without major disruption. It is important to know, however, that small blockchain networks are very vulnerable to mass attacks because the total hash ratio dedicated to the system is much lower than that of Bitcoin.

Conclusion

Through the combined use of game theory and cryptography, blockchain can have a higher level of security as a distributed system. However, to achieve this, almost all systems require these two areas of knowledge to be applied correctly. The right balance between decentralization and security is essential for the development of a reliable and effective digital currency network.

As blockchain uses evolve, their security systems will also change to meet the needs of different applications. Now, private blockchains are starting to be developed for companies, and they rely more on security through access control than on game theory (or cryptoeconomic) mechanisms that are not critical to the security of public blockchains.