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Documentation Index

Fetch the complete documentation index at: https://docs.phantom.com/llms.txt

Use this file to discover all available pages before exploring further.

The window.phantom.bitcoin provider will be deprecated in an upcoming release. Please plan to update any integrations that rely on this API.
When a dapp is connected to Phantom, it can also 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. Signing a message in the Phantom browser extension Phantom’s signMessage function accepts two parameters: an encoded message and an address that should be used to sign the message. It returns a Promise that resolves if the user approves the signature request. Once resolved, it contains the resulting signature. 
// function signature
function signMessage(
    address: string,
    message: Uint8Array,
  ): Promise<{
    signature: Uint8Array;
  }>;
The following is an example of how to construct and sign a message with Phantom: 
const message = new TextEncoder().encode('hello world');
const address = "bc1phajtersv55fwud5xr0t70p5234swy396a6avqhuny0qf83zssvrsm7tl4q"; // see "Establishing a Connection"
const { signature } = await phantomProvider.signMessage(address, message);
To verify that a message was signed by a given address, we recommend using the bip322-js library like so: 
import { Verifier } from "bip322-js";

// helper method
function bytesToBase64(bytes) {
  const binString = String.fromCodePoint(...bytes);
  return btoa(binString);
}

const isValidSignature = Verifier.verifySignature(
  address,
  new TextDecoder().decode(message),
  bytesToBase64(signature),
);
console.log(isValidSignature);
// true