L03: Consensus Mechanisms II Flashcards
How do PBFT consensus mechanism solve the Byzantine Generals’ Problem?
* Example: Hyperledger Fabric
* PBFT relies on a …
◦ View Changes: The network operates in ”views” with a …If the leader fails, the network elects a new leader.
◦ Three-Phase Commit:
1. Pre-prepare:The leader proposes a block.
2. Prepare…
3. Commit: Validators agree on the block and …
◦ Fault Tolerance: PBFT can tolerate up to f faulty nodes in a network of 3f + 1 nodes.
small number of nodes (validators) and is designed to work efficiently with up to a third of nodes acting maliciously.
designated primary node (leader) proposing blocks.
:Validators broadcast the proposal to others.
add it to the blockchain.
- PBFT achieves Byzantine Fault Tolerance as follows:
◦ Efficiency: …
◦ Strong Consistency: The multi-phase commit protocol ensures that …
◦ Leader Rotation: Regular leader rotation prevents a … or …
PBFT achieves consensus quickly with low latency in networks with known participants
all honest nodes agree on the same block
single point of failure; prolonged influence by a malicious node
Other prominent BFT-based consensus mechanisms
* Federated Byzantine Fault Tolerance (fBFT)
◦ fBFT operates by …, or quorum slices, which can overlap to ensure…
◦ This flexibility can improve … and ensure system reliability even with malicious nodes
* DiemBFT (dBFT)
◦ DiemBFT focuses on … through a leader-driven mechanism
◦ Improves …, making it suitable for high-volume transaction environments
allowing nodes to form their own trust circles; broader consensus without requiring the entire network’s agreement; scalability
achieving consensus rapidly among known validators
transaction throughput and reduces latency
- PoET:
◦ Each participating node in the network waits for a randomly chosen period, and
◦ Minimizes energy consumption as nodes are not required to perform complex calculations continuously and can …
◦ Concern of centralization as Intel, the creator of this consensus mechanism, solves the computing problem with its ready-made tool
the first node to complete this wait gets to add a block
even go to sleep during waiting time
Public blockchains:
Private blockchains:
PoW, PoS, DPoS
pBFT, PoET, dBFT, fBFT
Consensus mechanisms for central banking
Consumer Protection:
Market Integrity:
Financial Integrity:
Financial Stability:
Some consensus mechanisms can lead to poor outcomes for consumers if the mechanisms’ method of generating consensus leads to slow transactions times or high transaction costs. In cases where consumers are vulnerable or lack technical literacy, such costs can be unexpected and unacceptable.
Consensus mechanisms that are less secure could result in fraudulent transactions where malicious nodes are able to get access to the network through, for example, a 51 percent attack, or where a leader node has malicious intent. In financial markets, the result of such actions could lead to market manipulation and market abuse.
The pseudonymous nature of most DLT transactions can pose risks related to fraud, theft, money laun- dering, and terrorist financing. Although blockchains provide transparency, auditability, and immutabil- ity, end users and many market participants (such as nodes) are often not known, which can make sanctions or enforcement actions difficult to implement.
A small network of entities (or a single entity) could gain market dominance through private blockchains with consensus mechanisms that rely on permissioned access. This situation could create a network that has high barriers to entry, is nonsubstitutable, and that could become ”too big to fail.” Separately, where a crypto asset (such as a stablecoin or a CBDC) gains popular and widespread adoption, failure of the underlying consensus mechanisms could generate risks to financial stability.
- Delayed Proof of Work (dPoW): This mechanism secures a blockchain by…, more secure blockchain, providing …
- Leased Proof of Stake (LPoS): LPoS allows users to lease out their coins to a full node, which…, enabling them to earn rewards without …
- Proof of Stake Velocity (PoSV): PoSV is a consensus method that combines staking with transaction frequency to …, aiming to increase network velocity and participation.
- Simplified Byzantine Fault Tolerance (SBFT): A single validator can…
- Delegated Byzantine Fault Tolerance (DBFT): A consensus mechanism that utilizes a group of …, aiming to ensure blockchain integrity while …
delaying the notarization of transactions to a second; additional protection against attacks
participates in the consensus process on their behalf; needing to run a node themselves.
encourage both coin holding and spending
bundle proposed transactions and create a new block.
designated nodes to reach agreement; defending
against malicious actions.
- Directed Acyclic Graphs (DAG): DAGs do not have a blockchain data structure and …
- Proof of Activity (PoA): Uses both PoS and PoW to ensure the …. The miners pre-mine a block template rather than a complete one. Later, …
- Proof of Authority (PoA): Nodes participating in consensus will stake their reputation. The … are selected based on their true identities and have to …
- Proof of Reputation (PoR): Similar to Proof of Authority. A system where nodes in a network are weighted by reputation, which is built over time by their actions, to ensure that …
- Proof of History (PoH): A consensus mechanism that uses a … to create a historical record that proves that …
can handle transactions asynchronously.
reward points are on time; a validator validates the remaining block.
validating nodes; invest money and their reputation to earn their place on the platform.
only the most reliable participants are involved in the consensus process.
high-frequency verifiable delay function; an event has occurred at a specific moment in time.
- Proof of Importance (PoI): Users that … will be rewarded for that.
- Proof of Capacity (PoC): Users would use their available hard drive capacity to …. So, the larger your hard drive would be, the more you can validate blocks.
- Proof of Burn (PoB): A consensus method where miners send coins to an ”eater” address to burn them, which …
- Proof of Weight (PoWeight): A variation of Proof of Stake that factors in different types of resources, not just coin stake, to determine…
frequently send and receive transactions
select mining rights instead of using computational power
grants them the right to write blocks in proportion to the coins burnt.
a node’s power in the consensus process.
