Dark Pool DEX Architecture on Sui

System design and architecture specification for a MEV-resistant, private decentralized exchange on Sui.

Overview

Public AMMs face two main issues:

1. MEV & Front-running: Public mempools allow sandwich attacks.
2. State Contention: Global pool updates block parallel execution.

This design solves both using:

• Move Object Model: Owned objects for user positions (parallel path), Shared objects for liquidity pools.
• Programmable Transaction Blocks (PTB): Bundles price verification, swaps, and slippage checks into an atomic unit.
• ZK Dark Pool Layer: Validates order parameters off-chain using ZK proofs.

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Architecture

flowchart TD
    subgraph L1 ["1. Client & SDK Layer"]
        direction TB
        A["Frontend App"] --> B["Sui SDK (PTB Builder)"]
        B --> C1["1. Verify Oracle Price"]
        B --> C2["2. Execute Swap"]
    end

    subgraph L2 ["2. Execution Layer"]
        direction TB
        D["Atomic PTB Validation"] --> E["Parallel Execution Scheduler"]
    end

    subgraph L3 ["3. Move Smart Contracts"]
        direction TB
        F["LiquidityPool (Shared)"]
        G["UserPosition (Owned)"]
        H["ZK Verifier Contract"]
    end

    L1 --> L2 --> L3
    E --> F & G & H

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Components

1. Client & SDK Layer

Builds Programmable Transaction Blocks (PTBs):

• Enforces price and slippage checks before swap execution.
• If any check fails, the entire transaction block reverts.

2. Sui Network Execution Layer

Object Type	Role	Consensus
Shared Objects	Pools & Orderbook	Full Consensus
Owned Objects	User Positions & Tokens	Parallel Fast Path

3. ZK Proof Engine Specifications

Off-chain prover verifies 6 constraints:

1. AMM Invariant: (x · fee_den + Δx · fee_num)(y − Δy) ≥ xy · fee_den
2. Slippage Guard: Δy ≥ min_output
3. Pool Solvency: y > Δy
4. Commitment: Poseidon(secret, salt) == input_commitment
5. Nullifier: Poseidon(secret) == nullifier_hash
6. Merkle Inclusion: MerkleRoot(Poseidon(x, y)) == pool_state_root (depth 20)

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Execution Flow

1. Trader computes proof off-chain.
2. Client packages proof and PTB commands.
3. Network verifies proof, updates pool state, and outputs tokens to user position.