Blockchain Committee Election with Fairness Against Majority Coalitions
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Solution Overview
Problem
Existing leader election protocols in blockchain settings fail to achieve meaningful game-theoretic fairness against majority coalitions with round complexity less than log log n, and existing constructions are complex and not conceptually simple.
Innovation Solution
Developed O(log*n)-round leader election protocols using enhanced trapdoor permutations and collision-resistant hash functions, incorporating a 'commit and open' mechanism with a 'virtual identity' approach, achieving (1−o(1))-approximate fairness against (1−o(1))n-sized coalitions, and extending this to fair committee election.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tournament tree protocol is used for leader election, then game-theoretic fairness is achieved, but the round complexity increases to O(log n)
Solution Approach 1:
The protocol segments the n parties into n/c groups of size c, and elects a representative from each group in parallel. This segmentation allows the protocol to reduce round complexity from O(log n) to O(log log n) by performing multiple elimination rounds simultaneously across different groups, while maintaining game-theoretic fairness through the structured elimination process.
Solution Approach 2:
The protocol introduces a new dimension by using groups of size c > 1 instead of pairwise comparisons. This dimensional change from 1D (pairwise) to cD (group-based) allows parallel processing of multiple eliminations, reducing the depth of the elimination tree and thus the round complexity while preserving fairness guarantees.
2Adaptability or versatility
If the number of parties n is large, then the protocol can handle more participants, but the round complexity increases
Solution Approach 1:
The protocol divides n parties into n/c groups of size c, allowing the system to scale to large n while maintaining O(log log n) round complexity. The segmentation enables parallel elimination across multiple groups, so that increasing n does not linearly increase the number of rounds required.
Solution Approach 2:
The protocol performs elimination in batches of size c rather than one by one. This partial action approach processes multiple candidates simultaneously, reducing the total number of rounds needed to eliminate all but one party, even when n is large.
3Device complexity
If a simple tournament tree protocol is used, then the construction is conceptually simple, but it does not achieve meaningful fairness against majority coalitions with round complexity less than log log n
Solution Approach 1:
The protocol segments parties into groups of size c and uses structured elimination within each group to achieve meaningful fairness against majority coalitions. This segmentation enables the protocol to reach O(log log n) rounds while maintaining fairness, overcoming the limitation of simple tournament tree protocols.
Solution Approach 2:
The protocol changes the parameter of group size from c=2 (simple tournament tree) to c>2 (group-based elimination). This parameter change enables the protocol to achieve meaningful fairness against majority coalitions with reduced round complexity, as the larger group size allows for more efficient parallel elimination.
Data Source
AI summary
The disclosure relates to storing blockchain blocks committed to a blockchain based on a committee selection protocol executed in the presence of majority-sized coalitions while achieving a meaningful fairness guarantee in a small number of rounds, and whose round complexity is less than log log n, and storing a new block to the blockchain based on a protocol executed by the nodes of the next committee.