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Signing a Message

When a web application 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.
In order to send a message for the user to sign, a web application must:
  1. 1.
    Provide a hex or UTF-8 encoded string as a Uint8Array.
  2. 2.
    Request that the encoded message is signed via the user's Phantom wallet.
The handleSignMessage section of our developer sandbox provides an example of signing a message.
For more information on how to verify the signature of a message, please refer to tweetnacl-js.
signMessage()
request()
const provider = getProvider(); // see "Detecting the Provider"
const message = `To avoid digital dognappers, sign below to authenticate with CryptoCorgis`;
const encodedMessage = new TextEncoder().encode(message);
const signedMessage = await provider.signMessage(encodedMessage, "utf8");
const provider = getProvider(); // see "Detecting the Provider"
const message = `To avoid digital dognappers, sign below to authenticate with CryptoCorgis`;
const encodedMessage = new TextEncoder().encode(message);
const signedMessage = await provider.request({
method: "signMessage",
params: {
message: encodedMessage,
display: "hex",
},
});

Sign In With Solana (SIWS)

Developers who use signMessage to authenticate users can now take advantage of Phantom's new Sign In With Solana feature. For more information, please refer to our specification on GitHub.

Support for other "Sign In With" Standards

Phantom supports a range of Sign In With (SIW) message standards. You can read more about them here.