practical-stealth-addresses-code-1.md

import * as secp from '@noble/secp256k1'
import { hkdf } from '@noble/hashes/hkdf'
import { sha256 } from '@noble/hashes/sha256'

function makeSharedSecret(priv: Uint8Array, pub: Uint8Array, i: number) : Uint8Array {
  const secretNumber = secp.getSharedSecret(priv, pub, true).slice(1,33)
  const salt = ""
  const keyInfo = String(i)
  const keyLength = 64

  const derivedKey = hkdf(sha256, String(secretNumber), salt, info, keyLength)
  
  return derivedKey
}