Several ways are available to achieve decentralized security and trust with blockchain technology. A new block is always added in a linear and chronological manner. Therefore, they are always added at the end of the blockchain. Unless the network has reached consensus, it is extremely difficult to alter the contents of a block that has been added to the blockchain. Since every block contains its own hash along with the hash of the block before it, and the timestamp with it, each block contains its own hash. Mathematical functions are used to create hash codes, which are a string of numbers and letters. This means that the hash code will change if the information is modified in any way.
Consider a scenario in which a hacker, who runs a node on the blockchain network, would like to alter the blockchain and steal cryptocurrency. It would not align with everyone’s copy if they altered their own single copy. The other copies of the chains would look alike, but this one would stand out, and the hacker’s version would be cast away as invalid.
In order to be successful, such a hacker would need to simultaneously control and modify at least 51% of the blockchain copies so that their new copy becomes the majority copy and, thus, the agreed-upon chain. A similar attack would also require enormous amounts of money and resources, as each block would have a different time stamped and hash code, making re-doing them extremely time consuming.
As cryptocurrency networks are so large and growing so rapidly, it probably would be impossible to accomplish such a feat. Aside from being extremely expensive, this would also likely yield no results. If such a thing were done, it wouldn’t go unnoticed, as all blockchain users would notice such drastic changes. A new version of the chain not affected by the hard fork would be created for the members of the network. By doing so, the attacker would have control of a worthless asset, which makes the attack pointless. A bad actor would experience the same problem if they attacked the new fork of Bitcoin. The network is constructed in such a way that being part of it is more economically profitable than attacking it.
Blockchain versus Bitcoin
Researchers Stuart Haber and W. Scott Stornetta outlined blockchain technology for the first time in 1991, seeking to devise a system in which document timestamps cannot be altered. Blockchain had its first real-world application almost two decades later, with the December 2008 launch of Bitcoin.
A blockchain is at the heart of Bitcoin. Satoshi Nakamoto, the elusive creator of Bitcoin, described the digital currency as “a peer-to-peer electronic cash system, without a trusted third party” in a 1995 research paper.
Bitcoin makes use of blockchain as a method of transparently recording a ledger of payments, but blockchain can be used to unambiguously record any number of data points. A transaction may involve a vote in an election, an inventory of products or a deed to a house as examples.
The blockchain is currently being used in tens of thousands of projects beyond records of transactions. For example, it is being used as a secure voting system in democratic elections. The immutability of blockchains makes fraudulent voting less likely. One possibility is to implement a voting system in which each citizen of a country receives a cryptocurrency or token. A specific Bitcoin wallet address is then assigned to each candidate, and voters send their tokens to the address of the candidate they would like to vote for. With blockchain’s transparency and tamper-proof capabilities, there would be no need to count votes by hand and no way for bad actors to manipulate physical ballots.
The above article was short information on blockchain security. Hope this has proved helpful for the basics of blockchain.