Snippet of the SVS antibot server-side code.

Signing.js

const crypto = require("crypto")
const web3 = new (require("web3"))()

const PRIVATE_KEY = "0x"
const account = "0x", amount = 3

const nonce = crypto.randomBytes(9).toString("base64")
const content = web3.utils.soliditySha3({
  type: "address", 
  value: account
}, {
  type: "uint256",
  value: amount
}, {
  type: "string",
  value: nonce
})
const { messageHash: hash, signature } = await web3.eth.accounts.sign(content, PRIVATE_KEY)

return { hash, signature, nonce }