Go and JWT - Simple authentication

Note: This package github.com/dgrijalva/jwt-go is deprecated use this instead github.com/golang-jwt/jwt

To start, you need to import a JWT library in Golang (go get github.com/dgrijalva/jwt-go). You can find that library documentation in below link.

https://github.com/dgrijalva/jwt-go

Firstly, you need to create a token

// Create the token
token := jwt.New(jwt.SigningMethodHS256)
// Set some claims
token.Claims["foo"] = "bar"
token.Claims["exp"] = time.Now().Add(time.Hour * 72).Unix()
// Sign and get the complete encoded token as a string
tokenString, err := token.SignedString(mySigningKey)

Secondly, parse that token

token, err := jwt.Parse(myToken, func(token *jwt.Token) (interface{}, error) {
    // Don't forget to validate the alg is what you expect:
    if _, ok := token.Method.(*jwt.SigningMethodRSA); !ok {
        return nil, fmt.Errorf("Unexpected signing method: %v", token.Header["alg"])
    }
    return myLookupKey(token.Header["kid"]), nil
})

if err == nil && token.Valid {
    deliverGoodness("!")
} else {
    deliverUtterRejection(":(")
}

Also, there are some examples for use JWT in GOlang like this https://github.com/slok/go-jwt-example

EDIT-1

package main

import (
    "fmt"
    "time"

    "github.com/dgrijalva/jwt-go"
)

const (
    mySigningKey = "WOW,MuchShibe,ToDogge"
)

func main() {
    createdToken, err := ExampleNew([]byte(mySigningKey))
    if err != nil {
        fmt.Println("Creating token failed")
    }
    ExampleParse(createdToken, mySigningKey)
}

func ExampleNew(mySigningKey []byte) (string, error) {
    // Create the token
    token := jwt.New(jwt.SigningMethodHS256)
    // Set some claims
    token.Claims["foo"] = "bar"
    token.Claims["exp"] = time.Now().Add(time.Hour * 72).Unix()
    // Sign and get the complete encoded token as a string
    tokenString, err := token.SignedString(mySigningKey)
    return tokenString, err
}

func ExampleParse(myToken string, myKey string) {
    token, err := jwt.Parse(myToken, func(token *jwt.Token) (interface{}, error) {
        return []byte(myKey), nil
    })

    if err == nil && token.Valid {
        fmt.Println("Your token is valid.  I like your style.")
    } else {
        fmt.Println("This token is terrible!  I cannot accept this.")
    }
}

Just to make update of @massoud-afrashteh answer. In version 3 of jwt-go setting clams should be

// Set some claims
claims := make(jwt.MapClaims)
claims["foo"] = "bar"
claims["exp"] = time.Now().Add(time.Hour * 72).Unix()
token.Claims = claims

Don't forget to run the command go get github.com/dgrijalva/jwt-go.

Another way to create more simple:

token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
   "foo": "bar",
   "nbf": time.Date(2015, 10, 10, 12, 0, 0, 0, time.UTC).Unix(),
})
tokenString, err := token.SignedString([]byte("your key"))
fmt.Println(tokenString, err)