How does Cosmos achieve scalability without compromising on security or decentralization?

Cosmos achieves scalability while maintaining security and decentralization through its unique architecture and consensus mechanisms:

Zoned architecture: Cosmos comprises independent blockchain zones, each with a validator set, token, and application-specific functionality. This prevents bottlenecks.

Tendermint consensus: Zones use a BFT-style agreement quickly, like Tendermint, to agree on state. It is faster than proof-of-work with high throughput and low latency.

Inter-Blockchain Communication Protocol (IBC): Zones communicate in a decentralized manner through IBC, not across every full node. This reduces resource usage compared to all nodes processing all data.

Hub-spoke model: High-traffic zones can focus on specific applications with less congestion than a monolithic blockchain. The Cosmos Hub acts as a registry and inter-zone transaction layer.

Module system: Reusable components allow specialization, so zones only validate data relevant to their purpose, not the entire state. This enhances scalability.

SDK tools: Developers can easily build zones tailored to their use cases utilizing optimized module templates without sacrificing flexibility.

Together, this unique architecture achieves horizontal scalability by allowing new specialized zones to be added as needed without compromising the security model of individual zones or centralized bottlenecks. Scalability comes from specialization, not compromises to the core blockchain infrastructure.

How does the Tendermint consensus work, and why is it faster than proof-of-work?

Tendermint consensus uses a Byzantine Fault Tolerant (BFT) algorithm to add blocks to the blockchain in a decentralized manner. Here are some key aspects:

Validator nodes: A fixed set of validator nodes propose and vote on blocks in each round. This allows predictable performance without wasteful mining.

Voting: When a validator proposes a new block, other validators vote on its validity in a process like Practical Byzantine Fault Tolerance (PBFT).

Validation: Blocks are validated through lightweight signature verification rather than energy-intensive mining puzzles. This makes it much faster.

Threshold: A supermajority (e.g., 2/3) of the validators must approve each block for it to be committed to the chain. This secures it against attacker control.

Liveness: The algorithm is “live” meaning a block is produced promptly as long as ≥1/3 of validators are honest. Block times are shorter than PoW.

Finality: Once a supermajority is reached, the block is finalized and cannot be rewritten, even if validators go offline. PoW needs such probabilistic finality.

Performance: With a small validator set (<100 nodes), Tendermint can reach throughput in thousands of transactions per second while remaining decentralized. PoW scales less well.

Tendermint replaces mining with straightforward voting, allowing predictable high performance without wasteful resource usage common in PoW networks.

How the supermajority threshold is determined in the Tendermint consensus?

In Tendermint consensus, the threshold for a block to be committed or reach finality is determined based on the system’s total number of validator nodes. Specifically:

The threshold is always set at 2/3 of the total validator nodes (or 2/3 of voting power if validators have different voting weights).

For example, in a system with 100 validators, the threshold would be 67 validator votes (2/3 of 100).

This threshold ensures the blockchain can reach an agreement even if up to 1/3 of validators are behaving badly or have crashed.

The 1/3 fraction is based on Byzantine Fault Tolerance theory — it represents the maximum number of nodes that can be faulty or unreachable before consensus is impossible.

Tendermint dynamically recalculates the threshold whenever the total validator set changes to always keep it at 2/3 of the current size.

This provides resilience against validator dropouts or attacks as long as more than 1/3 of nodes remain honest.

So, in summary, setting the threshold at the optimal 2/3 fraction of voting power according to BFT allows Tendermint to guarantee consensus stability and blockchain survivability even when attacked or disrupted. It’s a key ingredient in Tendermint’s security properties.