Credentials

To setup Auth.js with external authentication mechanisms or simply use username and password, we need to use the Credentials provider. This provider is designed to forward any credentials inserted into the login form (.i.e username/password) to your authentication service via the authorize callback on the provider configuration.

Credentials Provider

First, let’s initialize the Credentials provider in the Auth.js configuration file. You’ll have to import the provider and add it to your providers array.

./auth.ts

import NextAuth from "next-auth"
import Credentials from "next-auth/providers/credentials"
// Your own logic for dealing with plaintext password strings; be careful!
import { saltAndHashPassword } from "@/utils/password"
 
export const { handlers, signIn, signOut, auth } = NextAuth({
  providers: [
    Credentials({
      // You can specify which fields should be submitted, by adding keys to the `credentials` object.
      // e.g. domain, username, password, 2FA token, etc.
      credentials: {
        email: {},
        password: {},
      },
      authorize: async (credentials) => {
        let user = null
 
        // logic to salt and hash password
        const pwHash = saltAndHashPassword(credentials.password)
 
        // logic to verify if the user exists
        user = await getUserFromDb(credentials.email, pwHash)
 
        if (!user) {
          // No user found, so this is their first attempt to login
          // meaning this is also the place you could do registration
          throw new Error("User not found.")
        }
 
        // return user object with their profile data
        return user
      },
    }),
  ],
})

/src/routes/plugin@auth.ts

import { QwikAuth$ } from "@auth/qwik"
import Credentials from "@auth/qwik/providers/credentials"
 
export const { onRequest, useSession, useSignIn, useSignOut } = QwikAuth$(
  () => ({
    providers: [
      Credentials({
        credentials: {
          email: { label: "Email" },
          password: { label: "Password", type: "password" },
        },
        async authorize(credentials) {
          const response = await getUserFromDb(credentials)
          if (!response.ok) return null
          return (await response.json()) ?? null
        },
      }),
    ],
  })
)

./src/auth.ts

import { SvelteKitAuth } from "@auth/sveltekit"
import Credentials from "@auth/sveltekit/providers/credentials"
// Your own logic for dealing with plaintext password strings; be careful!
import { saltAndHashPassword } from "@/utils/password"
 
export const { signIn, signOut, handle } = SvelteKitAuth({
  providers: [
    Credentials({
      // You can specify which fields should be submitted, by adding keys to the `credentials` object.
      // e.g. domain, username, password, 2FA token, etc.
      credentials: {
        email: {},
        password: {},
      },
      authorize: async (credentials) => {
        let user = null
 
        // logic to salt and hash password
        const pwHash = saltAndHashPassword(credentials.password)
 
        // logic to verify if user exists
        user = await getUserFromDb(credentials.email, pwHash)
 
        if (!user) {
          throw new Error("User not found.")
        }
 
        // return JSON object with the user data
        return user
      },
    }),
  ],
})

Don’t forget to re-export the handle in your ./src/hooks.server.ts file.

./src/hooks.server.ts

export { handle } from "./auth"

./src/routes/auth.route.ts

import { ExpressAuth } from "@auth/express"
import Credentials from "@auth/express/providers/credentials"
import express from "express"
// Your own logic for dealing with plaintext password strings; be careful!
import { saltAndHashPassword } from "@/utils/password"
 
const app = express()
app.use(
  "/auth/*",
  ExpressAuth({
    providers: [
      Credentials({
        // You can specify which fields should be submitted, by adding keys to the `credentials` object.
        // e.g. domain, username, password, 2FA token, etc.
        credentials: {
          email: {},
          password: {},
        },
        authorize: async (credentials) => {
          let user = null
 
          // logic to salt and hash password
          const pwHash = saltAndHashPassword(credentials.password)
 
          // logic to verify if the user exists
          user = await getUserFromDb(credentials.email, pwHash)
 
          if (!user) {
            // No user found, so this is their first attempt to login
            // meaning this is also the place you could do registration
            throw new Error("User not found.")
          }
 
          // return user object with the their profile data
          return user
        },
      }),
    ],
  })
)

If you’re using TypeScript, you can augment the User interface to match the response of your authorize callback, so whenever you read the user in other callbacks (like the jwt) the type will match correctly.

Signin Form

Finally, let’s create a simple sign-in form.

./components/sign-in.tsx

import { signIn } from "@/auth"
 
export function SignIn() {
  return (
    <form
      action={async (formData) => {
        "use server"
        await signIn("credentials", formData)
      }}
    >
      <label>
        Email
        <input name="email" type="email" />
      </label>
      <label>
        Password
        <input name="password" type="password" />
      </label>
      <button>Sign In</button>
    </form>
  )
}

/src/routes/index.tsx

import { component$ } from "@builder.io/qwik"
import { Form } from "@builder.io/qwik-city"
import { useSignIn } from "./plugin@auth"
 
export default component$(() => {
  const signInSig = useSignIn()
 
  return (
    <Form action={signInSig}>
      <label>
        Email
        <input name="email" type="email" />
      </label>
      <label>
        Password
        <input name="password" type="password" />
      </label>
      <button>Sign In</button>
    </Form>
  )
})

src/route/+page.svelte

<script>
  import { signIn } from "../auth"
  import { page } from "$app/stores"
 
  let email = ""
  let password = ""
</script>
 
<div>
  <form>
    <label>
      Email
      <input name="email" type="email" bind:value={email} />
    </label>
    <label>
      Password
      <input name="password" type="password" bind:value={password} />
    </label>
    <button on:click={() => signIn('credentials', { email, password })}>
      Log in
    </button>
  </form>
</div>

Verifying Data with Zod

To improve the security of your Credentials provider use, we can leverage a run-time schema validation library like Zod to validate that the inputs match what we expect.

npm install zod

pnpm add zod

yarn add zod

bun add zod

Next, we’ll setup the schema and parsing in our auth.ts configuration file, using the authorize callback on the Credentials provider.

./lib/zod.ts

import { object, string } from "zod"
 
export const signInSchema = object({
  email: string({ required_error: "Email is required" })
    .min(1, "Email is required")
    .email("Invalid email"),
  password: string({ required_error: "Password is required" })
    .min(1, "Password is required")
    .min(8, "Password must be more than 8 characters")
    .max(32, "Password must be less than 32 characters"),
})

./auth.ts

import NextAuth from "next-auth"
import { ZodError } from "zod"
import Credentials from "next-auth/providers/credentials"
import { signInSchema } from "./lib/zod"
// Your own logic for dealing with plaintext password strings; be careful!
import { saltAndHashPassword } from "@/utils/password"
import { getUserFromDb } from "@/utils/db"
 
export const { handlers, auth } = NextAuth({
  providers: [
    Credentials({
      // You can specify which fields should be submitted, by adding keys to the `credentials` object.
      // e.g. domain, username, password, 2FA token, etc.
      credentials: {
        email: {},
        password: {},
      },
      authorize: async (credentials) => {
        try {
          let user = null
 
          const { email, password } = await signInSchema.parseAsync(credentials)
 
          // logic to salt and hash password
          const pwHash = saltAndHashPassword(password)
 
          // logic to verify if the user exists
          user = await getUserFromDb(email, pwHash)
 
          if (!user) {
            throw new Error("User not found.")
          }
 
          // return JSON object with the user data
          return user
        } catch (error) {
          if (error instanceof ZodError) {
            // Return `null` to indicate that the credentials are invalid
            return null
          }
        }
      },
    }),
  ],
})

./lib/zod.ts

import { object, string } from "zod"
 
export const signInSchema = object({
  email: string({ required_error: "Email is required" })
    .min(1, "Email is required")
    .email("Invalid email"),
  password: string({ required_error: "Password is required" })
    .min(1, "Password is required")
    .min(8, "Password must be more than 8 characters")
    .max(32, "Password must be less than 32 characters"),
})

/src/routes/plugin@auth.ts

import { QwikAuth$ } from "@auth/qwik"
import Credentials from "@auth/qwik/providers/credentials"
import { signInSchema } from "./lib/zod"
 
export const { onRequest, useSession, useSignIn, useSignOut } = QwikAuth$(
  () => ({
    providers: [
      Credentials({
        credentials: {
          email: { label: "Email" },
          password: { label: "Password", type: "password" },
        },
        async authorize(credentials) {
          const { email, password } = await signInSchema.parseAsync(credentials)
 
          // Your logic here
        },
      }),
    ],
  })
)

./lib/zod.ts

import { object, string } from "zod"
 
export const signInSchema = object({
  email: string({ required_error: "Email is required" })
    .min(1, "Email is required")
    .email("Invalid email"),
  password: string({ required_error: "Password is required" })
    .min(1, "Password is required")
    .min(8, "Password must be more than 8 characters")
    .max(32, "Password must be less than 32 characters"),
})

./auth.ts

import SvelteKitAuth from "@auth/sveltekit"
import { ZodError } from "zod"
import Credentials from "@auth/sveltekit/providers/credentials"
import { signInSchema } from "./lib/zod"
// Your own logic for dealing with plaintext password strings; be careful!
import { saltAndHashPassword } from "@/utils/password"
import { getUserFromDb } from "@/utils/db"
 
export const { handle } = SvelteKitAuth({
  providers: [
    Credentials({
      // You can specify which fields should be submitted, by adding keys to the `credentials` object.
      // e.g. domain, username, password, 2FA token, etc.
      credentials: {
        email: {},
        password: {},
      },
      authorize: async (credentials) => {
        try {
          let user = null
 
          const { email, password } =
            await createUserSchema.parseAsync(credentials)
 
          // logic to salt and hash password
          const pwHash = saltAndHashPassword(password)
 
          // logic to verify if the user exists
          user = await getUserFromDb(email, pwHash)
 
          if (!user) {
            throw new Error("User not found.")
          }
 
          // return JSON object with the user data
          return user
        } catch (error) {
          if (error instanceof ZodError) {
            // Return `null` to indicate that the credentials are invalid
            return null
          }
        }
      },
    }),
  ],
})

⚠️

The industry has come a long way since usernames and passwords were first introduced as the go-to mechanism for authenticating and authorizing users to web applications. Therefore, if possible, we recommend a more modern and secure authentication mechanism such as any of the OAuth providers, Email Magic Links, or WebAuthn (Passkeys) options instead of username / password.

However, we also want to be flexible and support anything you deem appropriate for your application and use-case.

Magic Links WebAuthn 🔬

Credentials

Credentials Provider

Signin Form

Verifying Data with Zod

About Auth.js

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Acknowledgements