Sign Message

Calling signMessage

You can ask the user to sign a string message by using thesignMessage function in MetaKeep SDK. The function expects a non-empty reason which is shown to the user at the time of message signing.

The operation result is returned in the callback object passed to the signMessage function or the Promise object returned by the signMessage function.

This function is compliant with the official Ethereum sign API https://ethereum.org/en/developers/docs/apis/json-rpc/#eth_sign on EVM chains and is also supported on Solana and EOS.

sdk.signMessage(
    // message
    "Hello World",
    // signing reason
    "reason",
    // Callback
    Callback(
        onSuccess = { response: JsonResponse ->
            Log.d("onSuccess", response.toString())
        },
        onFailure = { error: JsonResponse ->
            Log.d("onFailure", error.toString())
        },
    ),
)

sdk.signMessage(
  // message
  message: "Hello World",
  // signing reason
  reason: "reason",
  // Callback
  callback: Callback(
    onSuccess: { (result: JsonResponse) in
      print("onSuccess")
      print(result.description)
    },
    onFailure: { (error: JsonResponse) in
      print("onFailure")
      print(error.description)
    }
  )
)

await sdk.signMessage(
    // message
    "Hello World",
    // signing reason
    "reason",
);

await sdk.signMessage(
    // message
    "Hello World",
    // signing reason
    "reason",
);

📘

Signing opaque binary data is not supported.

For security reasons, this API only supports signing human-readable UTF-8 strings. It is not intended for signing opaque binary data since then it can be used to sign an arbitrary hash, which means it can be used to sign transactions, or any other data, making it a dangerous phishing risk.

Use transaction signing for signing transaction data or typed data signing for signing generic data objects.

Response

On success, the callback onSuccess or the Promise resolve function is called with the signed message data as a JsonResponse object. This is what the data looks like:

{
  status: "SUCCESS",
  // Signature of the signed message.The signature encodes the r, s and v parameters 
  // from appendix F of the yellow paper in big-endian format. 
  // Bytes 0…32 contain the r parameter, bytes 32…64 the s parameter and the last byte the v parameter.
  signature: "0x1a84678f385553358386051464a252fa25d019335deb20262eb231d4ec1467300e6f1944e872430b7e04af6dd68ece90e2a9995a7abd827b50588602523b525600",
  r: "0x1a84678f385553358386051464a252fa25d019335deb20262eb231d4ec146730",
  s: "0x0e6f1944e872430b7e04af6dd68ece90e2a9995a7abd827b50588602523b5256",
  v: "0x0"
}

{
  "status": "SUCCESS",
  "signature": "0x2cf7781e2c29cbac6a9eaeb8b717f0ddd1f436362d27d97f1d2ca524cd0ec477a753a107dd945e249323f902cd7471141d31f62ea87d9b7432c3151af96c8801"
}

{
  "status": "SUCCESS",
  "signature": "SIG_K1_K1YY3maW1vHjQmmtciiQkkzPaUcpPdCQ631oMqayz4Z3TG9xhjNQwzqL3VCQPV1ZfYTQ14hkoRBkFaUwwrAngLedAxhog6"
}

Error status

Callback onFailure or the Promise reject function is called when the user cancels the operation or if there's an error. The error object contains a status field which is a string indicating the status of the operation. Here's what the error object looks like:

{
  status: "USER_CONSENT_DENIED"
}

Here's a table of all possible error status returned by the SDK

StatusDescription
USER_REQUEST_DENIEDThe user has denied the sign operation.
In this case, you should ask the user if they want to try again.
INVALID_REQUESTInvalid data passed to sign operation.
Please get in touch with us if you are unable to fix this.
APP_ID_REQUIREDNo app id was provided when initializing the SDK.
You can find the app ID in the MetaKeep Developer Console.
APP_NOT_FOUNDThe provided app id is invalid.
You can find the correct app id in the MetaKeep Developer Console.
SOMETHING_WENT_WRONGAn unknown error happened.
Please get in touch with us if you continue seeing this error.

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