SignMessage

After connecting to Backpack, an app can request that the user sign a message. Applications can create their own messages, which will be displayed to users from Backpack's signature prompt. Message signatures do not incur network fees and are a convenient way for apps to verify address ownership.

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-encoded it.

2. Request that the encoded message is signed via the user's Backpack wallet.

For more information on how to verify the signature of a message, please refer to Encryption Resources.

Base URL

https://backpack.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 session.

• nonce (required): A nonce used for encrypting the request, encoded in base58.

• redirect_link (required): The URI where Backpack should redirect the user upon completion. Please review Specifying Redirects for more details. URL-encoded.

• payload (required): An encrypted JSON string with the following fields:

  {
    "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. Backpack will display this message to the user when they are prompted to sign.

  • session (required): The session token received from the Connect method. Please see Handling Sessions for more details.

  • 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 to learn how apps can decrypt data using a shared secret. Encrypted bytes are encoded in base58.

  // 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, please refer to Encryption Resources.

Reject

An errorCode and errorMessage as query parameters.

Please refer to Errors for a full list of possible error codes.

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