Deterministic Verification with On-Chain Incremental Merkle Trees in Decentralized Lotteries

• Romulo de Moraes FURG
• Vinícius G. Pinto FURG
• Eder Gonçalves FURG
• Roger Immich UFRN
• Bruno L. Dalmazo FURG

DOI: https://doi.org/10.5753/cblockchain.2026.23185

Abstract

In large-scale lotteries, operational costs can make traditional approaches impractical. This paper proposes an architecture that addresses this limitation by introducing an on-chain Incremental Merkle Tree (IMT), which records a cryptographic commitment for each ticket purchase. During finalization, the contract requires that the submitted root matches the root derived from the IMT, preventing omission, address substitution, and fabricated sales in the commit phase, without requiring dispute windows or security deposits. We evaluate four implementations and show that the IMT-based variant preserves the favorable scalability of Merkle-based approaches while adding a constant overhead of ≈71k gas per purchase, regardless of the number of participants.

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