# Modes of Operation

HollowDB has two modus operandi: **proofs** and **whitelisting**; both can be enabled together, or separately.

<table><thead><tr><th width="146">Mode</th><th width="129">Put</th><th width="214">Update</th><th width="197">Remove</th><th>Get</th></tr></thead><tbody><tr><td><strong>Proofs</strong></td><td>-</td><td>Zero-Knowledge<br>Proof</td><td>Zero-Knowledge<br>Proof</td><td>-</td></tr><tr><td><strong>Whitelisting</strong></td><td>PUT<br>whitelist</td><td>UPDATE<br>whitelist</td><td>UPDATE<br>whitelist</td><td>-</td></tr></tbody></table>

## Using Proofs

Using zero-knowledge proofs gives full control to the users on updating the value at their key. When proofs are enabled:

* Anyone can **read** and **put**.
* To **update** or **remove** a value at some key, user must provide a zero-knowledge proof (ZKP) of preimage knowledge of that key.

HollowDB makes use of a circuit that we call "HollowDB Authentication" circuit, to which you can find more information at:

{% content-ref url="/pages/K1ubBVfaRO6f3H9LTHdx" %}
[HollowDB Authentication](/zero-knowledge-proofs/hollowdb-authentication.md)
{% endcontent-ref %}

You can enable or disable proof checking with the following Admin command:

```typescript
const isProofRequired = true; // or false
await admin.updateProofRequirement("auth", isProofRequired);
```

If you are deploying your own contract, you must also provide the verification key that the proof verifier will use. You can find HollowDB's keys [here](https://github.com/firstbatchxyz/hollowdb/tree/master/config/circuits). You can either provide the key in the initial state, or use the Admin to update the verification key at a later time:

```typescript
await admin.updateVerificationKey("auth", newVerificationKey);
```

## Using Whitelisting

Whitelisting is an alternative authorization mechanism that can be used within HollowDB. It can provide a fine-grained control over who can put, update, or remove a value to the database. When whitelisting is enabled:

* Anyone can **read**.
* To **put**, the user must have been put-whitelisted by the contract owner.
* To **update** or **remove**, the user must have been update-whitelisted by the contract owner.

There is a separate whitelist for put and update/remove. You can enable/disable them with the Admin:

```typescript
const isPutWhitelistRequired = true; // or false
const isUpdateWhitelistRequired = true; // or false
await admin.updateWhitelistRequirement('put', isPutWhitelistRequired);
await admin.updateWhitelistRequirement('update', isUpdateWhitelistRequired);
```

You can add & remove users from the whitelist using the Admin:

```typescript
const whitelistType = "put"; // or "update"

// add some users
const addressesToAdd = [address1, address2 /*, ... */];
await admin.updateWhitelist(addressesToAdd, whitelistType, 'add');

// remove some users
const addressesToRemove = [address3, address4 /*, ... */];
await admin.updateWhitelist(addressesToRemove, whitelistType, 'remove');
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.hollowdb.xyz/hollowdb/modes-of-operation.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.