LEP-5 - Cascade Availability Commitment (Merkle Proof Challenge)

• Status: Implemented
• Author: Lumera Protocol Team
• Created: 2025-02-08
• Requires: LEP1 (Minimizing Cascade Metadata Size)

This file is the canonical LEP-5 specification for the lumera implementation. It incorporates implementation-stage drift from the original proposal, including BLAKE3 hashing, client-provided challenge_indices, and per-level odd-node duplication in the Merkle tree.

1. Executive Summary

1.1 The Problem

The current Cascade protocol has a critical vulnerability: a malicious SuperNode can finalize actions and claim fees without ever receiving or storing the actual file data.

This attack is possible because:

• All information needed to compute valid rq_ids_ids is available on-chain (creator's signature + counter)
• The verification formula uses only on-chain metadata
• No proof of actual file possession is required at finalization

Impact:

• Users pay fees but data is never stored
• Network storage guarantees are undermined
• Malicious operators can extract value without providing service

1.2 The Solution

Introduce an Availability Commitment system that requires the finalizing SuperNode to prove possession of actual file data: