How to Sign and Verify a Message

The primary function of a keypair is to sign messages and enable verification of the signature. Verification of a signature allows the recipient to be sure that the data was signed by the owner of a specific private key.

To do so, we can use the TweetNaCl crypto library:

import { Keypair } from "@solana/web3.js";
import nacl from "tweetnacl";
import { decodeUTF8 } from "tweetnacl-util";

const keypair = Keypair.fromSecretKey(
  Uint8Array.from([
    174, 47, 154, 16, 202, 193, 206, 113, 199, 190, 53, 133, 169, 175, 31, 56,
    222, 53, 138, 189, 224, 216, 117, 173, 10, 149, 53, 45, 73, 251, 237, 246,
    15, 185, 186, 82, 177, 240, 148, 69, 241, 227, 167, 80, 141, 89, 240, 121,
    121, 35, 172, 247, 68, 251, 226, 218, 48, 63, 176, 109, 168, 89, 238, 135,
  ]),
);

const message = "The quick brown fox jumps over the lazy dog";
const messageBytes = decodeUTF8(message);

const signature = nacl.sign.detached(messageBytes, keypair.secretKey);
const result = nacl.sign.detached.verify(
  messageBytes,
  signature,
  keypair.publicKey.toBytes(),
);

console.log(result);