Deno creating an TOTP token (two factor authentication)

index.ts

import { generateOTPToken, generateSecret, generateQRCode } from './utils.ts'

// registering a new user

if (username) {
  const u: User = {
    username,
    email
  }
  const user = await createUser(u) // create your user and create an auth secret
  const authToken = generateOTPToken(generateSecret(user.secret), u.email)
  const qr = await generateQRCode(authToken.toString())

  // qr is the image to scan in auth apps
  // In deno fresh use this:
  // <img src={props.data.qr} alt="auth qr code" />
  return await ctx.render({
    qr
  })

}

// validating users
const authToken = generateOTPToken(generateSecret(user.secret), u.email)
const token = authToken.generate()
let delta = totp.validate({
    token,
    window: 1
})
// delta: null if invalid, 0 if correct, and -amount if token has changed (a minute passed)

utils.ts

import * as OTPAuth from 'https://deno.land/x/[email protected]/dist/otpauth.esm.js'
import { qrcode } from 'https://deno.land/x/[email protected]/mod.ts'

const opts = {
	issuer: 'MyWebsite',
	algorithm: 'SHA1',
	digits: 6,
	period: 30,
}

export function generateOTPToken (secret: string|OTPAuth.Secret, label: string) {
  return new OTPAuth.TOTP({
    ...opts,
    label,
    secret
  })
}

export function generateSecret (secret: string) {
  return OTPAuth.Secret.fromUTF8(secret)
}

export default function generateQRCode(str: string) {
  return qrcode(str)
}