> ## Documentation Index
> Fetch the complete documentation index at: https://docs.phantom.com/llms.txt
> Use this file to discover all available pages before exploring further.

# SignMessage

> Request a message signature via Phantom deeplink to verify address ownership without network fees.

Once it's connected to Phantom, an app can request that the user signs a given message. Applications are free to write their own messages which will be displayed to users from within Phantom's signature prompt. Message signatures do not involve network fees and are a convenient way for apps to verify ownership of an address.

In order to send a message for the user to sign, an application must:

1. Provide a **hex** or **UTF-8** encoded string as a Uint8Array and then **base58-encode it**.
2. Request that the encoded message is signed via the user's Phantom wallet.

The [deeplinking demo app](/resources/sandbox) provides an example of signing a message.

<Info>
  The message to be signed must be passed as a base58-encoded string. For more information on how to verify the signature of a message, please refer to [Encryption resources](/phantom-deeplinks/encryption).
</Info>

## Base URL

```
https://phantom.app/ul/v1/signMessage
```

## Query string parameters

* `dapp_encryption_public_key` (required): The original encryption public key used from the app side for an existing [Connect](/phantom-deeplinks/provider-methods/connect) session.
* `nonce` (required): A nonce used for encrypting the request, encoded in base58.
* `redirect_link` (required): The URI where Phantom should redirect the user upon completion. For more details, see [Specify redirects](/phantom-deeplinks/specifying-redirects). URL-encoded.
* `payload` (required): An encrypted JSON string with the following fields:

  ```json theme={null}
  {
    "message": "...", // the message, base58 encoded
    "session": "...", // token received from connect-method
    "display": "utf8" | "hex", // the encoding to use when displaying the message 
  }
  ```

  * `message` (required): The message that should be signed by the user, encoded in base58. Phantom will display this message to the user when they are prompted to sign.
  * `session` (required): The session token received from the [Connect](/phantom-deeplinks/provider-methods/connect) method. For more details, see [Handle sessions](../handling-sessions).
  * `display` (optional): How you want us to display the string to the user. Defaults to `utf8`.

## Returns

### Approve

* `nonce`: A nonce used for encrypting the response, encoded in base58.
* `data`: An encrypted JSON string. Refer to [Encryption](/phantom-deeplinks/encryption) to learn how apps can decrypt `data` using a shared secret. Encrypted bytes are encoded in base58.

  ```json theme={null}
  // content of decrypted `data`-parameter
  {
      signature: "...", // message-signature
  }
  ```

  * `signature`: The message signature, encoded in base58. For more information on how to verify the signature of a message, see [Encryption resources](/phantom-deeplinks/encryption).

### Reject

An `errorCode` and `errorMessage` as query parameters. For a full list of possible error codes, see [Errors](/solana/errors).

```
{
  "errorCode": "...",
  "errorMessage": "..."
}
```

## Example

Refer to the [signMessage](https://github.com/phantom-labs/deep-link-demo-app/blob/20f19f2154e98699f0d5a6b28bc4bb3d5acbcefd/App.tsx#L290) method implemented in our React Native demo application.