Wanchain Galaxy Consensus Proof of Stake Technical Deep Dive: Pt. 4
Delegation Mechanism
Deep Dive Series:
Part 1: General Overview
Part 2: Random Number Generation
Part 3: Leader Selection Algorithms
Part 4: Delegation Mechanism
Part 5: Economic Incentives
In the previous two articles, we introduced two core algorithms of Galaxy Consensus, the random number generation algorithm and the leader selection algorithm. These two algorithms ensure that the consensus process can proceed safely and steadily after. The question still remains, how can we promote the participation of all token holders? This article will detail how Wanchain’s delegation mechanism answers that question.
1. Galaxy Consensus Delegation Mechanism Design Background
There are already many PoS consensus mechanisms in the blockchain industry. They have been proposed by rigorous and meticulous academics and industry experts with rich experience, but they are generally lacking in practicality.
The following points are of particular concern:
High participation threshold
While PoS consensus protocols do not require the high computing power and investment in expensive mining hardware associated with PoW protocols, there are sill requirements for certain level of computing power and network bandwidth in order to for participants to successfully take part in consensus. This means that PoS participants still need to invest a certain amount in getting their nodes set up in running. Cost will vary depending on whether the node operators use AWS or get set up on bare metal, but the fact remains that there are some costs of getting set up and running. This, combined with the PoS principal that participants are rewarded in proportion to the amount of stake they hold, establishes a certain threshold for participation. Participants will only be able to profitably join in consensus when the protocol rewards are higher than their operation costs. This establishes a certain minimum threshold which will shut out a certain number of participants. This is a not a part of the protocol’s theoretical design, but it is still a practical concern.
Centralization risk
Due to the high participation threshold, only larger stake holders can profitably participate in the PoS consensus process to obtain rewards. The consensus gains obtained will increase the gap between consensus participants and non-participants, and thus will lead to a vicious circle of “the rich get richer and the poor get poorer”, which may eventually lead to increased centralization.
Risk of violating basic security assumptions
The security foundation of almost all PoS consensus mechanisms is the honest majority assumption, that is, honest nodes make up the majority of participants in the protocol. While the honest majority assumption may be true for all stakeholders in the network taken as a group, it may not be true for all stakeholders who can pass the participation threshold. If there is a very high participation threshold which prohibits many stakeholders from joining, then participants will be chosen from a much smaller pool of stakeholders which might not represent the entire network. This is essentially a sampling problem. The higher the threshold, the smaller the sample, and the less likely the set of participants reflects the nature of all stakeholders in the network. The issue is therefore how to design a mechanism which can reduce the participation threshold in order to absorb as much stake from as many participants as possible.
2. The significance of Galaxy Consensus’s delegation mechanism
We have from the start considered practicality when it comes to the design of Galaxy Consensus. By practicality we refer not only to reducing the computational and storage requirements needed to participate in the consensus process, but more importantly, to ensuring that stake holders can smoothly participate throughout the process. Galaxy Consensus has a robust delegation mechanism in which nodes with larger amounts of stake can participate directly in the consensus process, while smaller WAN holders can join through the delegation mechanism. In theory, any WAN holder can join the consensus process, which is in the spirit of our open and inclusive PoS design. Under this scheme, more WAN will join the protocol, making the entire network more secure and robust. Therefore, the delegation mechanism reduces the threshold for PoS consensus participation, improving the practicality of Galaxy Consensus, and has several advantages compared with other PoS consensus protocols.
3. The theoretical basis of Galaxy Consensus’s delegation mechanism — proxy signatures
A proxy signature is a special signature algorithm in cryptography that enables an individual, the Original Signer, to delegate his or her right to sign a message to another individual, the Proxy Signer. The Proxy Signer can calculate a delegate signature, and any individual with the Original Signer’s public key can verify the validity of the signature. Strictly speaking, the proxy signature algorithm is a collection of multiple algorithms,
PS = (G, K, S, V, (D,P), PS, PV)
where G, K, S, V make up a standard digital signature algorithm (such as ECDSA), D, P are algorithms for delegating and accepting delegations, PS is the proxy signature generation algorithm, and PV is the proxy signature verification algorithm.
4. Galaxy Consensus’s Delegation Mechanism Process
The delegation mechanism of Galaxy Consensus was designed by the Wanchain research team as a universal, secure, and efficient delegation mechanism. The mechanism is based on the Triple ECDSA Proxy Signature algorithm, which, combined with smart contracts, implements a complete delegation mechanism. The mechanism enables any WAN holder to join the Galaxy Consensus, contribute to network security, and gain protocol rewards.
Suppose Alice is a normal WAN holder with public-private key pair (pkᵢ, skᵢ),and Bob is a galaxy consensus proxy node with public-private key pair (pkⱼ, skⱼ). Proxy_SC is a special smart contract used to verify and store data in the delegation process. Alice wants to delegate her rights to Bob to participate in Galaxy Consensus on her behalf. The detailed process is as follows:
Step 1: Alice locally enters her private key skᵢ and Bob’s public key pkⱼ into the triple ECDSA algorithm to generate a delegation certificate:
cert =（pkᵢ,pkⱼ,ω,(R,s)）
Step 2: Alice constructs a transaction, sends the delegation certificate to Proxy_SC, and sends her WAN to be locked in Proxy_SC.
Step 3: Proxy_SC verifies the validity of the proxy certificate issued by Alice, and generates the proxy public key pkp and the delegation certificate to be stored in the contract.
Step 4: Bob parses the certificate stored in Proxy_SC and calculates the proxy private key skp by using its own private key skⱼ.
Step 5: The proxy public key pkp participates in the galaxy consensus as an independent identity, and Bob completes the consensus process by using the proxy private key skp and receives the consensus reward.
Step 6: Consensus rewards are distributed between Alice and Bob according to the specified rate in the smart contract.
Step 7: After the delegation period ends, Proxy_SC will return the entrusted funds to Alice’s account.
5. Advantages of the galaxy consensus delegation mechanism
Universality
The mechanism uses the ECDSA signature algorithm in standard signatures, stake delegation, and proxy signatures. This algorithm is also widely used in the blockchain field. It is fully compatible with existing blockchain architectures. The verification logic for participants is completely consistent for both directly registering to join the consensus mechanism and for joining through the delegation mechanism.
Non-interactive
The process of delegation is non-interactive, so there is no need to establish a secure communication channel between the Original Signer and the Proxy Signer. The delegation is completed completely through the on chain transactions leading to a more efficient consensus process.
Secure
Some existing delegation mechanisms require the delegating party to transfer funds into the proxy node’s account, and the proxy node then directly participates in consensus and manually distributes consensus rewards. This method is centralized and trust based. It relies entirely on the honesty of the proxy node. Our delegation mechanism is implemented based entirely on cryptographic algorithms. The stake of the WAN holder is locked in a smart contract, not held by the proxy node. The proxy node only obtains the right of the WAN holder to participate in consensus, and does not have any control over the staked funds, so users are fully protected.
Open and Transparent
Through our mechanism, the delegation process and the data of the nodes participating in the consensus process are all stored in the chain, and all the data is transparent. This both promotes proxy nodes to behave non-maliciously, while it also makes it possible for WAN holders to analyze the activities of proxy nodes and select an appropriate node based on their history.
About Wanchain
Wanchain is the infrastructure connecting the decentralized financial world. Wanchain’s live cross-blockchain solution is EVM-based, includes optional private transactions, and provides a decentralized, permissionless, and secure approach for interoperability. Wanchain has employees globally with teams in Beijing (China), Austin (USA), London (UK), Kuala Lumpur (Malaysia), Paris (France), and Madrid (Spain).
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