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slide 16 · consensus
Consensus algorithms
PoW
PoS
DPoS
PBFT
Run a round of , , and side by side and compare trade-offs.
- 1Run a round of each algorithm
- 2Compare speed, cost and trust
- 3Pick the right one for a use case
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Sybil resistance
Spend electricity
Energy
Very high
Finality
Probabilistic (6 blocks)
Throughput
7 – 30
One round of Proof of Work
- 01all miners assemble candidate blocks from the mempool
- 02each brute-forces nonces: SHA-256(header) < target
- 03miner #418 finds a valid nonce after 2.1×10^22 attempts
- 04block gossiped; every node re-verifies in milliseconds
- 05chain grows · reversal now costs re-mining the block
01 algorithm: Proof of Work
02 used by: Bitcoin, Litecoin, Dogecoin
03 attack threshold: 51% of hash power
Strengths
- +Simplest, most battle-tested
- +Permissionless: no stake needed
- +Attack cost is physical and external
Trade-offs
- −Enormous energy use
- −Mining pools re-centralise hash power
- −Never truly final, only improbable to revert
Comparison
| Metric | PoW | PoS | DPoS | PBFT |
|---|---|---|---|---|
| Energy | Very high | Very low (~99.9% less) | Very low | Negligible |
| Finality | Probabilistic (6 blocks) | Deterministic after 2 epochs | Seconds | Immediate, single block |
| Throughput | 7 – 30 | 15 – 100 | 1,000 – 4,000 | 1,000 – 10,000 (small sets) |
| Fault threshold | 51% of hash power | 1/3 stake to stall, 2/3 to finalise a lie | Majority of the small delegate set | Tolerates f faults with 3f+1 nodes |
| Used by | Bitcoin, Litecoin, Dogecoin | Ethereum, Cardano | EOS, Tron, BNB Chain | Hyperledger Fabric, Tendermint-style chains |
There is no winner — only different answers to "who is allowed to write next, and what stops them lying?" answers with electricity, with capital at risk, with elected representatives, with known identities and a lot of messaging.