dag_signData

Creates a request to generate a safe signature of arbitrary data from the selected wallet. This method is intended to be used for interaction with custom data requests to metagraphs and other similar use cases.

This method adds a standard "\u0019Constellation Signed Data:\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 Data:\n" + len(message) + "\n" + message

Warning

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

Parameters​

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

Return Type​

HexString - The prefixed ECDSA signature.

Base64

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

JSONEncoded

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

StringEncoded

/**
 * A String encoded
 * */
type StringEncoded = string;

Example​

// Build the signature request
const signatureRequest: any = {
  field1: "content_field_1",
  field2: {
    field2_1: true,
    field2_2: 12332435,
    field2_3: {
      field2_3_1: "content_field2_3_1",
    },
  },
  field3: [1, 2, 3, 4],
  field4: null,
};

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

// Encode the string directly if "signatureRequest" is a string:
// const signatureRequest = "This is a custom string.";
//
//                                      Base64 < String
// const signatureRequestEncoded = window.btoa(signatureRequest);

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

Verify​

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

// Build the same signature request
const signatureRequest: any = {
  field1: "content_field_1",
  field2: {
    field2_1: true,
    field2_2: 12332435,
    field2_3: {
      field2_3_1: "content_field2_3_1",
    },
  },
  field3: [1, 2, 3, 4],
  field4: null,
};

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

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

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

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

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