> For the complete documentation index, see [llms.txt](https://void-protocol-2.gitbook.io/void-protocol-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://void-protocol-2.gitbook.io/void-protocol-docs/developers/proof-service.md).

# Proof Service

VOID uses a **hosted proof service** to generate zero-knowledge proofs using **Noir circuits** and **UltraHonk proofs**.

### Circuits

The current proof system supports:

* **Shield** — deposits into private balance
* **Transfer** — Private Send
* **Unshield** — withdrawals
* **Trade** — Private Buy, Private Sell and Private Swap

{% hint style="info" %}
The legacy **Swap** verifier is still deployed, but the pool's legacy fixed-rate swap entry point is **permanently disabled**. Private Buy, Sell and Swap all use the **Trade** circuit.
{% endhint %}

### Trust Model

The hosted proof service receives the prover inputs required for each request, including note data.

The proof service:

* does **not** control user keys
* cannot authorize a spend by itself
* cannot independently move user funds
* generates proofs that are verified on-chain before execution

Spending still requires the user's keys.

{% hint style="warning" %}
The hosted proof service can see the data supplied for proof generation.

This means users are currently trusting the operator with the privacy of those prover inputs.
{% endhint %}

### What the Proof Service Cannot Do

<table data-view="cards"><thead><tr><th></th><th></th></tr></thead><tbody><tr><td><strong>Spend Funds</strong></td><td>It cannot spend private notes without the user's keys.</td></tr><tr><td><strong>Change Proof Rules</strong></td><td>Proofs must satisfy the deployed circuit rules and pass on-chain verification.</td></tr><tr><td><strong>Bypass Verification</strong></td><td>An invalid proof is rejected by the verifier contract.</td></tr></tbody></table>

### Local Proving

**Local browser proving is planned.**

This will allow proofs to be generated on the user's device rather than sending prover inputs to the hosted proof service.

{% hint style="info" %}
Local proving is intended to remove the current privacy dependency on the hosted prover.

It is not live on Robinhood Chain Testnet today.
{% endhint %}

### Before Mainnet

Planned production improvements include:

* local browser proving
* rate limits
* abuse protection
* proof-request timeouts
* queue limits
* production monitoring and reliability controls

{% hint style="warning" %}
The current hosted prover is part of the testnet architecture and should not be treated as the final mainnet trust model.
{% endhint %}


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