(2021-03-29) Behnke How Polkadots Parachain Model Reimagines Blockchain Security

Rob Behnke: How Polkadot's Parachain Model Reimagines Blockchain Security. Blockchains can be attacked in a variety of different ways. However, the most famous potential blockchain attack is the 51% attack against Proof of Work (PoW) blockchains.

To protect themselves against 51% attacks, PoW blockchain networks try to attract as much hashrate as they can. However, hashrate is a finite resource

As blockchain becomes more popular, these security limitations stand in the way of growth and scalability

Some blockchains are using sidechains to tap into the security of secure, stable blockchains, but the Polkadot Network is taking a different approach.

The Security of Sidechains

Cross-chain functionality has become common in an attempt to expand the functionality and scalability of a blockchain.

Sidechains also enable a blockchain to scale because - in most cases - the transactions performed on a sidechain are not recorded on the mainchain.

While sidechains have their benefits, security is a major limitation. Two sidechains that are pegged together are each responsible for their own security. If one of the networks is the victim of a 51% attack, the value of the associated cryptocurrency can fall

Polkadot’s Shared Security Model and Blockchain Security

The Polkadot network consists of up to one hundred parallel chains or “parachains”

The main requirement that Polkadot places on a parachain is that any state transitions performed on a parachain must be communicated to and verified by the Polkadot Relay Chain.

Balancing Scalability and Security

Polkadot has built a system where different blockchains are incentivized to pool their resources to secure the system as a whole.