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SignMessage

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. 1.
    Provide a hex or UTF-8 encoded string as a Uint8Array and then base58-encoded it.
  2. 2.
    Request that the encoded message is signed via the user's Phantom wallet.
The deeplinking demo app provides an example of signing a message.
For more information on how to verify the signature of a message, please refer to Encryption Resources.

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 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. 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. Phantom 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": "..."
}

Example