# Sign Message SDK

To sign a message a user  / an account would need to have to have been register and authenticated  by going through  [Register using SDK](/authentication/passkeys/registration/register-using-sdk.md) flow. 

Once you have registered the user, you can choose one of the below 2 flows

## **Session-Based Authentication**

In order to use this flow, you must  [Authenticating with SDK](/authentication/passkeys/authentication/authenticating-with-sdk.md) first to obtain a JWT.  Here is a sample of how to use it

```javascript
import { Passport } from "@0xpass/passport";
import { WebauthnSigner } from "@0xpass/webauthn-signer";
import { stringToHex } from "viem";
import { Passport } from "@0xpass/passport";
import { WebauthnSigner } from "@0xpass/webauthn-signer";

const signer = new WebauthnSigner({
      rpId: window.location.hostname,
      rpName: "rpName",
});

const passport = new Passport({
    scopeId: "insert_your_scope_id",
    signer: signer
});

const userInput {
   username: "insert_registered_username_here"
   userDisplayName: "insert_registered_user_display_name_here"
}

await passport.setupEncryption();
await passport.authenticate(userInput);

// Generate a signature
const signature = await passport.signMessage(stringToHex("hello world!"));
console.log(signature);
```

### signMessage Parameters

| Parameter | Description                    | Example Values                                                |
| --------- | ------------------------------ | ------------------------------------------------------------- |
| `message` | The message you'd like to sign | `68656c6c6f20776f726c64` (hex represenation of "hello world") |

#### signMessage Response

A successful response will return the following, a signature of the signed message by the authenticated account.

```json
{
    "jsonrpc": "2.0",
    "result": "signature_here",
    "id": 1
}
```

## **Direct Passkey Authentication**

Since you will be directly authenticating with Passkeys here, you don't need to go through authentication step. Here is a code sample:

```javascript
import { Passport } from "@0xpass/passport";
import { WebauthnSigner } from "@0xpass/webauthn-signer";
import { stringToHex } from "viem";
import { Passport } from "@0xpass/passport";
import { WebauthnSigner } from "@0xpass/webauthn-signer";

const signer = new WebauthnSigner({
      rpId: window.location.hostname,
      rpName: "rpName",
});

const passport = new Passport({
    scope_id: "insert_your_scope_id",
    signer: signer
    allow_sessions: false
});

const userInput {
   username: "insert_registered_username_here"
   userDisplayName: "insert_registered_user_display_name_here"
}

await passport.setupEncryption();
//This step is different for direct authentication
passport.setUserData(userInput)

// Generate a signature
const signature = await passport.signMessage(stringToHex("hello world!"));
console.log(signature);
```

### signMessage Parameters

| Parameter | Description                    | Example Values                                                |
| --------- | ------------------------------ | ------------------------------------------------------------- |
| `message` | The message you'd like to sign | `68656c6c6f20776f726c64` (hex represenation of "hello world") |

#### signMessage Response

A successful response will return the following, a signature of the signed message by the authenticated account.

```json
{
    "jsonrpc": "2.0",
    "result": "signature_here",
    "id": 1
}
```


---

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