# Security Model Overview

### Access Control

All protocol operations are gated by the [InventoryPoolDefaultAccessManager01.sol](https://github.com/nomial-io/nomial-contracts-v1/blob/main/src/owners/InventoryPoolDefaultAccessManager01.sol) contract, which implements OpenZeppelin’s AccessControl and adds custom roles (`VALIDATOR_ROLE`, `BORROWER_ROLE`) on top of `DEFAULT_ADMIN_ROLE`.

### Validator Sign-Off Mechanism

Off-chain validators run clients that monitor system state across all deployed chains. Every protected operation requires a **strict majority** of the active validator set to sign off—e.g., with four validators, at least three must approve. The access manager verifies replay-protected signatures against the `VALIDATOR_ROLE`, ensuring only a majority consensus executes critical functions.

### Collateral Lock & Withdrawal Process

Collateral in Nomial V1 is managed by the [`CollateralPool01`](https://github.com/nomial-io/nomial-contracts-v1/blob/67549ad721ace334fbd727dda49e91d283291008/src/CollateralPool01.sol) contract, which enforces a two-phase, time-locked withdrawal mechanism. Collateral can be liquidated to cover a borrower's debt if they fail to repay their loan. Validators enforce collateral requirements at their discretion. A majority of validator signatures is required to trigger collateral liquidation.

### Loan Process

Borrowers must obtain majority validator sign-off for all borrows. Additionally, borrowers must be granted the `BORROWER_ROLE` in order to borrow funds from an inventory pool. Collateral requirements, enforced by validators, ensure that borrowers have an incentive to repay their debt.

### Administrative Operations

Administrative changes (interest‐rate parameter changes, validator and borrower set updates, pool state overrides) can only be performed by the default admin address **with the validator majority.**

### Permissionless Actions

Two core user operations remain permissionless

* **LP Deposits & Withdrawals** in [`InventoryPool01.sol`](https://github.com/nomial-io/nomial-contracts-v1/blob/main/src/InventoryPool01.sol)
* **Loan Repayments** in [`InventoryPool01.sol`](https://github.com/nomial-io/nomial-contracts-v1/blob/main/src/InventoryPool01.sol)

### Threat Model

An attacker must compromise a strict majority of validator private keys **and** the default admin key to execute any privileged action or steal funds from inventory pools. If an attacker compromises a borrower key, the collateral provided by the borrower can be liquidated to recover the value of stolen funds.

By combining role-based access control with an off-chain validator set and a strict-majority threshold, Nomial V1 minimizes trust in any single party. An adversary would have to control both a majority of validators and a privileged access account key (admin or borrower) in order to exploit the system.


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