Is Blockchain secure?
Technically, a blockchain is a record list growing eventually and are linked using certain methodology. The idea of using blockchain is to allow people specifically those with trust issues to share valuable and important data in a way where it is secured and cannot be tampered. The data is kept authentic and safe as the storage has an elite math and software innovation with extreme rules which cannot be manipulated by any attackers. The system security is the most appropriate design which has very rare chances of failure and can only be hindered by some skilful rules or smart math only taken up by skillful thieves.
Understanding the theory:
To actually know how the security system in blockchains works we can use Bitcoin as an example. The blockchain for bitcoin keeps a track of all the transactions that take place in the bitcoin present and history as a ledger of accounts which is stored and structured in the software within multiple copies on a specific network of a set of computers generally termed as nodes. Whenever someone submits the transaction details into a ledger, these are checked by the nodes to get the validity assurance based on its details and pre-study data. They are further packed as valid and its subset is turned in blocks to add to the already ongoing chain. The block owners are termed as minors who can add new block into a chain in order to get rewarded.
The protocol of consensus which is the method with which nodes in a specific network consensually settle on a shared history and the fingerprint (cryptographic) which is the unique system assets which make it ideally tamperproof. Hash as the fingerprint is called requires a lot of time in computation and initial generating energy serving as a proof that the block added by the miner do the work for a reward in the form of bitcoin. Once it is verified and the hash replicates its respective block, and once the nodes have done their jobs, the copies are updated in the new block.
The final prime yet elemental part is the link of hashes in the blockchain with the previous one. As a result, any change in ledger needs to be reflected subsequently in every block faster with respect to the other nodes to avoid any new addition to the new block making it tamperproof.
Cheaters escape routes:
The implementation is way harder than the theory! Even if it is considered a safe tool, one can skillfully cheat with basic technical knowledge being a miner whose greedy and selfish gain an upper hand on the nodes for wasting time on pre solved puzzles. One can also experience an eclipse attack which means the blockchain nodes are consistent with respect to the other comparable date and once an attacker takes control of a node and its communication, he or she can fool in false data acceptance wasting large amounts of resources and giving affirmations on fake and unreasonable transactions. Hackers can sometimes break through the wallets, tamper the details and burst the safe vacuum zone.
The real anticipation:
Everyone thought that the decentralization of blockchain will guarantee security! Once attacked or the network is hacked, it is really hard to revive a large amount of computation power for network subversion. Some experts say that the protocols should be altered and new ones shall be evolved whereas others encourage the blockchains which need joining permission which creates authority crises. One can only vouch for the fact the system operations are efficient and should be closely monitored with consistency to avoid thefts.
Popular Hashing Algorithms used in Blockchain:
- MD 5 Algorithm: This algorithm produces 128-bit hash. But the resistance was broken after ~2^21 hashes.
- SHA 1: This algorithm produces 160-bit hash. But the collision resistance broke after ~2^61 hashes.
- SHA 256: This algorithm produces a 256-bit hash. Bitcoin is currently using SHA 256 algorithm for hashing.
- Keccak-256: This algorithm also produces a 256-bit hash. Ethereum blockchain network is currently using this algorithm for hashing.