dag_signMessage

Creates a request to generate a safe signature of typed message data from the selected wallet. This method is intended to be used for general message signing use cases such as verifying the ownership of a wallet.

This method adds a standard "\u0019Constellation Signed Message:\n" + len(message) + "\n" prefix when calculating the signature hash. The addition of the prefix prevents users from being tricked into signing a valid token transaction with this method.

The final string looks like this: "\u0019Constellation Signed Message:\n" + len(message) + "\n" + message

Warning

Please be sure you use the correct prefix for the correct method when verifying signatures, dag_signMessage uses "Constellation Signed Message:" while dag_signData uses "Constellation Signed Data:"

Parameters​

Name	Type	Description
Account	Address	Account to sign from.
Request	Base64<JSONEncoded<SignatureRequest>>	Signature Request.

Return Type​

HexString - The constellation ecdsa signature.

Base64

/**
 * A base64 encoded string
 * */
type Base64 = string;

JSONEncoded

/**
 * A JSON encoded string
 * */
type JSONEncoded = string;

JSONScalarValue

type JSONScalarValue = null | string | number | boolean;

SignatureRequest

type SignatureRequest = {
  content: string;
  metadata: Record<string, JSONScalarValue>;
};

Example​

// Build the signature request
const signatureRequest: SignatureRequest = {
  content: "Sign this message to confirm your address",
  metadata: {
    user: "3feb69d6-d3f0-4812-9c93-384bee08afe8",
  },
};

// Encode the signature request - Base64 < JSON < Request
const signatureRequestEncoded = window.btoa(JSON.stringify(signatureRequest));

await provider.request({
  method: "dag_signMessage",
  params: ["DAG88C9WDSKH451sisyEP3hAkgCKn5DN72fuwjfX", signatureRequestEncoded],
});
// "3045022100b35798008516373fcc6eef75fe8e322ce8fe0dccc4802b052f3ddc7c6b5dc2900220154cac1e4f3e7d9a64f4ed9d2a518221b273fe782f037a5842725054f1c62280"

Verify​

In order to verify the signature you can use the verify() method from dag4.js:

// Build the same signature request
const signatureRequest: SignatureRequest = {
  content: "Sign this message to confirm your address",
  metadata: {
    user: "3feb69d6-d3f0-4812-9c93-384bee08afe8",
  },
};

// get the public key
const publicKey = await provider.request({
  method: "dag_getPublicKey",
  params: [
    "DAG88C9WDSKH451sisyEP3hAkgCKn5DN72fuwjfX", // Your DAG address
  ],
});

// same request used in dag_signMessage
const signatureRequestEncoded = window.btoa(JSON.stringify(signatureRequest));

// hash returned by dag_signMessage in the pevious example
const signature =
  "3045022100b35798008516373fcc6eef75fe8e322ce8fe0dccc4802b052f3ddc7c6b5dc2900220154cac1e4f3e7d9a64f4ed9d2a518221b273fe782f037a5842725054f1c62280";

const message = `\u0019Constellation Signed Message:\n${signatureRequestEncoded.length}\n${signatureRequestEncoded}`;

const result = await dag4.keyStore.verify(publicKey, message, signature);
// true -> verification succeeded
// false -> verification failed