[Awesome Go, Iris] Iris enable JSON Web Tokens (JWT) middleware to authenticate MCV resources

Posted on 2021-03-13 Edited on 2024-09-12 In Programming Language , Golang (Go) , Awesome Go , Web Framework (WF) / Web Application Framework (WAF) , Iris Views: Word count in article: 4.4k Reading time ≈ 4 mins.

Iris JSON Web Tokens (JWT) Middleware

JSON Web Token (JWT) is an open standard (RFC 7519 - https://tools.ietf.org/html/rfc7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed. JWTs can be signed using a secret (with the HMAC algorithm) or a public/private key pair using RSA or ECDSA.

When should you use JSON Web Tokens?

Here are some scenarios where JSON Web Tokens are useful:

Authorization: This is the most common scenario for using JWT. Once the user is logged in, each subsequent request will include the JWT, allowing the user to access routes, services, and resources that are permitted with that token. Single Sign On is a feature that widely uses JWT nowadays, because of its small overhead and its ability to be easily used across different domains.
Information Exchange: JSON Web Tokens are a good way of securely transmitting information between parties. Because JWTs can be signed—for example, using public/private key pairs—you can be sure the senders are who they say they are. Additionally, as the signature is calculated using the header and the payload, you can also verify that the content hasn’t been tampered with.

Read more about JWT at: https://jwt.io/introduction/

Using JWT with Iris

The Iris JWT middleware was designed with security, performance and simplicity in mind, it protects your tokens from critical vulnerabilities that you may find in other libraries. It is based on kataras/jwt package.

package main

import (
    "time"

    "github.com/kataras/iris/v12"
    "github.com/kataras/iris/v12/middleware/jwt"
)

var (
    sigKey = []byte("signature_hmac_secret_shared_key")
    encKey = []byte("GCM_AES_256_secret_shared_key_32")
)

type fooClaims struct {
    Foo string `json:"foo"`
}

func main() {
    app := iris.New()

    signer := jwt.NewSigner(jwt.HS256, sigKey, 10*time.Minute)
    // Enable payload encryption with:
    // signer.WithEncryption(encKey, nil)
    app.Get("/", generateToken(signer))

    verifier := jwt.NewVerifier(jwt.HS256, sigKey)
    // Enable server-side token block feature (even before its expiration time):
    verifier.WithDefaultBlocklist()
    // Enable payload decryption with:
    // verifier.WithDecryption(encKey, nil)
    verifyMiddleware := verifier.Verify(func() interface{} {
        return new(fooClaims)
    })

    protectedAPI := app.Party("/protected")
    // Register the verify middleware to allow access only to authorized clients.
    protectedAPI.Use(verifyMiddleware)
    // ^ or UseRouter(verifyMiddleware) to disallow unauthorized http error handlers too.

    protectedAPI.Get("/", protected)
    // Invalidate the token through server-side, even if it's not expired yet.
    protectedAPI.Get("/logout", logout)

    // http://localhost:8080
    // http://localhost:8080/protected?token=$token (or Authorization: Bearer $token)
    // http://localhost:8080/protected/logout?token=$token
    // http://localhost:8080/protected?token=$token (401)
    app.Listen(":8080")
}

func generateToken(signer *jwt.Signer) iris.Handler {
    return func(ctx iris.Context) {
        claims := fooClaims{Foo: "bar"}

        token, err := signer.Sign(claims)
        if err != nil {
            ctx.StopWithStatus(iris.StatusInternalServerError)
            return
        }

        ctx.Write(token)
    }
}

func protected(ctx iris.Context) {
    // Get the verified and decoded claims.
    claims := jwt.Get(ctx).(*fooClaims)

    // Optionally, get token information if you want to work with them.
    // Just an example on how you can retrieve all the standard claims (set by signer's max age, "exp").
    standardClaims := jwt.GetVerifiedToken(ctx).StandardClaims
    expiresAtString := standardClaims.ExpiresAt().Format(ctx.Application().ConfigurationReadOnly().GetTimeFormat())
    timeLeft := standardClaims.Timeleft()

    ctx.Writef("foo=%s\nexpires at: %s\ntime left: %s\n", claims.Foo, expiresAtString, timeLeft)
}

func logout(ctx iris.Context) {
    err := ctx.Logout()
    if err != nil {
        ctx.WriteString(err.Error())
    } else {
        ctx.Writef("token invalidated, a new token is required to access the protected API")
    }
}