Common myths of blockchain

I came know about these myths and their realities through an EY report titled "Blockchain Benchmarking study" published in coordination with Cambridge Centre for Alternative Finance and Visa. Please look into this report; it's worth a read!

Myth: Blockchain is trustless

In reality,  blockchain may reduce the need of trust but they can't completely eliminate the trust factor completely. For example, you are placing trust in the cryptography which is the underlying stack. For a permissioned network, you need to put trust on the operator or the validator. For some usage of the same such as governance, there might be need of a trusted third party

Myth: Blockchain is tamper-proof

If nodes decide to collude, then transactions can be reversed and can be removed from database. For blockchain to be tamper proof, mining of blockchain should be as decentralized as possible. Permissionless blockchain are the best examples of decentralization of this while permissioned networks are the most suspectible to tampering.

Myth: Blockchain is 100 percent secure

Blockchain uses cryptography for authentication of transaction, permission enforcement, validation of transaction and integrity verification of data. These are controlled by some private keys and once these private keys are "hacked" and if they constitute more than 51%, it is known as "51% attack" and they get full access to shared network and can change transaction history as they desire.

Myth: Blockchain is a truth machine

A blockchain can only verify for what it has been built i.e. whether its true or false. For any other inputs from "outside world", it treats them as garbage. So, for that blockchain its "garbage in and garbage out". For e.g. Ethereum can not be inserted in a bitcoin blockchain until and unless a third party is employed to verify and guarantee the accuracy of the input while being inserted into the blockchain.