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@dgrijalva @vongohren @bruston
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package jwt
import (
// TimeFunc provides the current time when parsing token to validate "exp" claim (expiration time).
// You can override it to use another time value. This is useful for testing or if your
// server uses a different time zone than your tokens.
var TimeFunc = time.Now
// Parse methods use this callback function to supply
// the key for verification. The function receives the parsed,
// but unverified Token. This allows you to use properties in the
// Header of the token (such as `kid`) to identify which key to use.
type Keyfunc func(*Token) (interface{}, error)
// A JWT Token. Different fields will be used depending on whether you're
// creating or parsing/verifying a token.
type Token struct {
Raw string // The raw token. Populated when you Parse a token
Method SigningMethod // The signing method used or to be used
Header map[string]interface{} // The first segment of the token
Claims Claims // The second segment of the token
Signature string // The third segment of the token. Populated when you Parse a token
Valid bool // Is the token valid? Populated when you Parse/Verify a token
// Create a new Token. Takes a signing method
func New(method SigningMethod) *Token {
return NewWithClaims(method, MapClaims{})
func NewWithClaims(method SigningMethod, claims Claims) *Token {
return &Token{
Header: map[string]interface{}{
"typ": "JWT",
"alg": method.Alg(),
Claims: claims,
Method: method,
// Get the complete, signed token
func (t *Token) SignedString(key interface{}) (string, error) {
var sig, sstr string
var err error
if sstr, err = t.SigningString(); err != nil {
return "", err
if sig, err = t.Method.Sign(sstr, key); err != nil {
return "", err
return strings.Join([]string{sstr, sig}, "."), nil
// Generate the signing string. This is the
// most expensive part of the whole deal. Unless you
// need this for something special, just go straight for
// the SignedString.
func (t *Token) SigningString() (string, error) {
var err error
parts := make([]string, 2)
for i, _ := range parts {
var jsonValue []byte
if i == 0 {
if jsonValue, err = json.Marshal(t.Header); err != nil {
return "", err
} else {
if jsonValue, err = json.Marshal(t.Claims); err != nil {
return "", err
parts[i] = EncodeSegment(jsonValue)
return strings.Join(parts, "."), nil
// Parse, validate, and return a token.
// keyFunc will receive the parsed token and should return the key for validating.
// If everything is kosher, err will be nil
func Parse(tokenString string, keyFunc Keyfunc) (*Token, error) {
return new(Parser).Parse(tokenString, keyFunc)
func ParseWithClaims(tokenString string, claims Claims, keyFunc Keyfunc) (*Token, error) {
return new(Parser).ParseWithClaims(tokenString, claims, keyFunc)
// Encode JWT specific base64url encoding with padding stripped
func EncodeSegment(seg []byte) string {
return strings.TrimRight(base64.URLEncoding.EncodeToString(seg), "=")
// Decode JWT specific base64url encoding with padding stripped
func DecodeSegment(seg string) ([]byte, error) {
if l := len(seg) % 4; l > 0 {
seg += strings.Repeat("=", 4-l)
return base64.URLEncoding.DecodeString(seg)
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