const CONTENT_TOPIC = `/fileshare/1/room-${roomId}/proto`;
// Create Waku's encoder and decoder
const encoder = createEncoder({ contentTopic: CONTENT_TOPIC });
const decoder = createDecoder(CONTENT_TOPIC);
```
{% hint style="info" %}
Note that *content topics* are metadata strings embedded into outgoing messages that facilitate protocol-level features like selectively processing incoming messages. These strings can be thought of as 'channels', which determine, among other things, the path of messages through the network. Learn more about content topics [here](https://docs.waku.org/learn/concepts/content-topics/).
{% endhint %}
### 3. Send and receive Waku messages
```typescript
// Function that handles the received message
const messageHandler = (wakuMessage: DecodedMessage) => {
}
// Subscribe to content topic
const subscription = await lightNode.filter.subscribe(
[decoder],
messageHandler
);
// Send a message
const serializedMessage = FileMessage.encode(protoMessage).finish();
await node.lightPush.send(
encoder,
{ payload: serializedMessage }
)
```
### 4. Download and upload files from Codex
{% hint style="info" %}
Codex uses a REST API to interact with the nodes, so the complexity of handling HTTP requests is intentionally omitted in this section to keep the focus on the essential concepts. Only the relevant parts are show. The complete documentation for this API is in the [Codex API](https://api.codex.storage/) page.
{% endhint %}
Upload a file to Codex:
```typescript
const url = `/api/codex/v1/data`;
const xhr = new XMLHttpRequest();
// The file to be uploaded
const file = ... [File]
xhr.setRequestHeader('Content-Type', file.type);
xhr.setRequestHeader(
'Content-Disposition',
`attachment; filename='${file.name}'`
);
xhr.onload = function () {
if (xhr.status >= 200 && xhr.status < 300) {
// Extract the CID from the response
const cid =
typeof response === 'object'
? response.id ||
response.cid ||
(response.data && (response.data.id || response.data.cid))
: response;
}
}
xhr.send(file);
```
Download a file from Codex:
// CID is the Codex file ID.
const cid = ...
const downloadUrl = `/api/codex/v1/data/${cid}/network/stream`;
const response = await fetch(downloadUrl, {
method: 'GET',
headers: {
Accept: '*/*',
...(this.authHeaders || {}),
},
mode: 'cors',
credentials: 'include',
});
const data = await response.blob();
### 5. Encryption and decryption with TACo
Initialize TACo:
```typescript
await initialize()
```
Define access conditions:
const condition = new conditions.base.rpc.RpcCondition({
chain: chainId,
method: "eth_getBalance",
parameters: [":userAddress", "latest"],
returnValueTest: {
comparator: ">",
value: 0,
},
});
Encrypt files:
const ritualId = 27 // This is a testnet-specific ritual ID
// Read file as ArrayBuffer
const arrayBuffer = await file.arrayBuffer();
const data = new Uint8Array(arrayBuffer);
const messageKit = await encrypt(
provider,
domain,
data,
condition,
ritualId,
encryptorSigner // ethers.Signer
);
const bytesToUpload = messageKit.toBytes();
Decrypt files:
```typescript
const messageKit = ThresholdMessageKit.fromBytes(encryptedBytes);
const authProvider = new EIP4361AuthProvider(provider, signer);
const conditionContext =
conditions.context.ConditionContext.fromMessageKit(messageKit);
conditionContext.addAuthProvider(
USER_ADDRESS_PARAM_DEFAULT,
authProvider
);
const result = await decrypt(
provider,
domain,
messageKit,
conditionContext
);
```
***
## Using Waku + Codex + TACo in production
Waku is currently used to enable private communication in applications such as RAILGUN and Status. Research and development continue with their decentralized DoS protection protocol being trialed on testnet.
*Codex* is currently operating a public, non-incentivized testnet that is open to developers and contributors.
Regarding *TACo*, the parameters specified in this guide are for testing and hacking only. For real-world use cases, the production version of *TACo* is required – i.e. a funded Mainnet `ritualID` which connects the encrypt/decrypt API to a cohort of independently operated nodes, and corresponds to a DKG public key generated by independent parties.
Ready to use *TACo* in production? Check out the [Mainnet Access](/migration-to-mainnet/mainnet-taco-beta-program.md) section for everything you need.
---
# 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.taco.build/for-developers/access-control/integrations/waku-+-codex.md?ask=
```
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.