jwt

package module
Version: v3.2.2+incompatible Latest Latest
Warning

This package is not in the latest version of its module.

Go to latest
Published: Jul 30, 2021 License: MIT Imports: 18 Imported by: 198

README

jwt-go

build Go Reference

A go (or 'golang' for search engine friendliness) implementation of JSON Web Tokens.

IMPORT PATH CHANGE: Starting from v3.2.1, the import path has changed from github.com/dgrijalva/jwt-go to github.com/golang-jwt/jwt. After the original author of the library suggested migrating the maintenance of jwt-go, a dedicated team of open source maintainers decided to clone the existing library into this repository. See dgrijalva/jwt-go#462 for a detailed discussion on this topic.

Future releases will be using the github.com/golang-jwt/jwt import path and continue the existing versioning scheme of v3.x.x+incompatible. Backwards-compatible patches and fixes will be done on the v3 release branch, where as new build-breaking features will be developed in a v4 release, possibly including a SIV-style import path.

SECURITY NOTICE: Some older versions of Go have a security issue in the crypto/elliptic. Recommendation is to upgrade to at least 1.15 See issue dgrijalva/jwt-go#216 for more detail.

SECURITY NOTICE: It's important that you validate the alg presented is what you expect. This library attempts to make it easy to do the right thing by requiring key types match the expected alg, but you should take the extra step to verify it in your usage. See the examples provided.

Supported Go versions

Our support of Go versions is aligned with Go's version release policy. So we will support a major version of Go until there are two newer major releases. We no longer support building jwt-go with unsupported Go versions, as these contain security vulnerabilities which will not be fixed.

What the heck is a JWT?

JWT.io has a great introduction to JSON Web Tokens.

In short, it's a signed JSON object that does something useful (for example, authentication). It's commonly used for Bearer tokens in Oauth 2. A token is made of three parts, separated by .'s. The first two parts are JSON objects, that have been base64url encoded. The last part is the signature, encoded the same way.

The first part is called the header. It contains the necessary information for verifying the last part, the signature. For example, which encryption method was used for signing and what key was used.

The part in the middle is the interesting bit. It's called the Claims and contains the actual stuff you care about. Refer to RFC 7519 for information about reserved keys and the proper way to add your own.

What's in the box?

This library supports the parsing and verification as well as the generation and signing of JWTs. Current supported signing algorithms are HMAC SHA, RSA, RSA-PSS, and ECDSA, though hooks are present for adding your own.

Examples

See the project documentation for examples of usage:

Extensions

This library publishes all the necessary components for adding your own signing methods. Simply implement the SigningMethod interface and register a factory method using RegisterSigningMethod.

Here's an example of an extension that integrates with multiple Google Cloud Platform signing tools (AppEngine, IAM API, Cloud KMS): https://github.com/someone1/gcp-jwt-go

Compliance

This library was last reviewed to comply with RTF 7519 dated May 2015 with a few notable differences:

  • In order to protect against accidental use of Unsecured JWTs, tokens using alg=none will only be accepted if the constant jwt.UnsafeAllowNoneSignatureType is provided as the key.

Project Status & Versioning

This library is considered production ready. Feedback and feature requests are appreciated. The API should be considered stable. There should be very few backwards-incompatible changes outside of major version updates (and only with good reason).

This project uses Semantic Versioning 2.0.0. Accepted pull requests will land on main. Periodically, versions will be tagged from main. You can find all the releases on the project releases page.

While we try to make it obvious when we make breaking changes, there isn't a great mechanism for pushing announcements out to users. You may want to use this alternative package include: gopkg.in/golang-jwt/jwt.v3. It will do the right thing WRT semantic versioning.

BREAKING CHANGES:*

  • Version 3.0.0 includes a lot of changes from the 2.x line, including a few that break the API. We've tried to break as few things as possible, so there should just be a few type signature changes. A full list of breaking changes is available in VERSION_HISTORY.md. See MIGRATION_GUIDE.md for more information on updating your code.

Usage Tips

Signing vs Encryption

A token is simply a JSON object that is signed by its author. this tells you exactly two things about the data:

  • The author of the token was in the possession of the signing secret
  • The data has not been modified since it was signed

It's important to know that JWT does not provide encryption, which means anyone who has access to the token can read its contents. If you need to protect (encrypt) the data, there is a companion spec, JWE, that provides this functionality. JWE is currently outside the scope of this library.

Choosing a Signing Method

There are several signing methods available, and you should probably take the time to learn about the various options before choosing one. The principal design decision is most likely going to be symmetric vs asymmetric.

Symmetric signing methods, such as HSA, use only a single secret. This is probably the simplest signing method to use since any []byte can be used as a valid secret. They are also slightly computationally faster to use, though this rarely is enough to matter. Symmetric signing methods work the best when both producers and consumers of tokens are trusted, or even the same system. Since the same secret is used to both sign and validate tokens, you can't easily distribute the key for validation.

Asymmetric signing methods, such as RSA, use different keys for signing and verifying tokens. This makes it possible to produce tokens with a private key, and allow any consumer to access the public key for verification.

Signing Methods and Key Types

Each signing method expects a different object type for its signing keys. See the package documentation for details. Here are the most common ones:

  • The HMAC signing method (HS256,HS384,HS512) expect []byte values for signing and validation
  • The RSA signing method (RS256,RS384,RS512) expect *rsa.PrivateKey for signing and *rsa.PublicKey for validation
  • The ECDSA signing method (ES256,ES384,ES512) expect *ecdsa.PrivateKey for signing and *ecdsa.PublicKey for validation
JWT and OAuth

It's worth mentioning that OAuth and JWT are not the same thing. A JWT token is simply a signed JSON object. It can be used anywhere such a thing is useful. There is some confusion, though, as JWT is the most common type of bearer token used in OAuth2 authentication.

Without going too far down the rabbit hole, here's a description of the interaction of these technologies:

  • OAuth is a protocol for allowing an identity provider to be separate from the service a user is logging in to. For example, whenever you use Facebook to log into a different service (Yelp, Spotify, etc), you are using OAuth.
  • OAuth defines several options for passing around authentication data. One popular method is called a "bearer token". A bearer token is simply a string that should only be held by an authenticated user. Thus, simply presenting this token proves your identity. You can probably derive from here why a JWT might make a good bearer token.
  • Because bearer tokens are used for authentication, it's important they're kept secret. This is why transactions that use bearer tokens typically happen over SSL.
Troubleshooting

This library uses descriptive error messages whenever possible. If you are not getting the expected result, have a look at the errors. The most common place people get stuck is providing the correct type of key to the parser. See the above section on signing methods and key types.

More

Documentation can be found on pkg.go.dev.

The command line utility included in this project (cmd/jwt) provides a straightforward example of token creation and parsing as well as a useful tool for debugging your own integration. You'll also find several implementation examples in the documentation.

Documentation

Overview

Package jwt is a Go implementation of JSON Web Tokens: http://self-issued.info/docs/draft-jones-json-web-token.html

See README.md for more info.

Example (GetTokenViaHTTP)
package main

import (
	"bytes"
	"crypto/rsa"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"strings"

	"github.com/golang-jwt/jwt"
)

var (
	verifyKey *rsa.PublicKey

	serverPort int
)

func fatal(err error) {
	if err != nil {
		log.Fatal(err)
	}
}

// Define some custom types were going to use within our tokens
type CustomerInfo struct {
	Name string
	Kind string
}

type CustomClaimsExample struct {
	*jwt.StandardClaims
	TokenType string
	CustomerInfo
}

func main() {
	// See func authHandler for an example auth handler that produces a token
	res, err := http.PostForm(fmt.Sprintf("http://localhost:%v/authenticate", serverPort), url.Values{
		"user": {"test"},
		"pass": {"known"},
	})
	if err != nil {
		fatal(err)
	}

	if res.StatusCode != 200 {
		fmt.Println("Unexpected status code", res.StatusCode)
	}

	// Read the token out of the response body
	buf := new(bytes.Buffer)
	io.Copy(buf, res.Body)
	res.Body.Close()
	tokenString := strings.TrimSpace(buf.String())

	// Parse the token
	token, err := jwt.ParseWithClaims(tokenString, &CustomClaimsExample{}, func(token *jwt.Token) (interface{}, error) {
		// since we only use the one private key to sign the tokens,
		// we also only use its public counter part to verify
		return verifyKey, nil
	})
	fatal(err)

	claims := token.Claims.(*CustomClaimsExample)
	fmt.Println(claims.CustomerInfo.Name)

}
Output:

test
Example (UseTokenViaHTTP)
package main

import (
	"bytes"
	"crypto/rsa"
	"fmt"
	"io"
	"log"
	"net/http"
	"time"

	"github.com/golang-jwt/jwt"
)

var (
	signKey    *rsa.PrivateKey
	serverPort int
)

func fatal(err error) {
	if err != nil {
		log.Fatal(err)
	}
}

// Define some custom types were going to use within our tokens
type CustomerInfo struct {
	Name string
	Kind string
}

type CustomClaimsExample struct {
	*jwt.StandardClaims
	TokenType string
	CustomerInfo
}

func main() {

	// Make a sample token
	// In a real world situation, this token will have been acquired from
	// some other API call (see Example_getTokenViaHTTP)
	token, err := createToken("foo")
	fatal(err)

	// Make request.  See func restrictedHandler for example request processor
	req, err := http.NewRequest("GET", fmt.Sprintf("http://localhost:%v/restricted", serverPort), nil)
	fatal(err)
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %v", token))
	res, err := http.DefaultClient.Do(req)
	fatal(err)

	// Read the response body
	buf := new(bytes.Buffer)
	io.Copy(buf, res.Body)
	res.Body.Close()
	fmt.Println(buf.String())

}

func createToken(user string) (string, error) {

	t := jwt.New(jwt.GetSigningMethod("RS256"))

	t.Claims = &CustomClaimsExample{
		&jwt.StandardClaims{

			ExpiresAt: time.Now().Add(time.Minute * 1).Unix(),
		},
		"level1",
		CustomerInfo{user, "human"},
	}

	return t.SignedString(signKey)
}
Output:

Welcome, foo

Index

Examples

Constants

View Source
const (
	ValidationErrorMalformed        uint32 = 1 << iota // Token is malformed
	ValidationErrorUnverifiable                        // Token could not be verified because of signing problems
	ValidationErrorSignatureInvalid                    // Signature validation failed

	// Standard Claim validation errors
	ValidationErrorAudience      // AUD validation failed
	ValidationErrorExpired       // EXP validation failed
	ValidationErrorIssuedAt      // IAT validation failed
	ValidationErrorIssuer        // ISS validation failed
	ValidationErrorNotValidYet   // NBF validation failed
	ValidationErrorId            // JTI validation failed
	ValidationErrorClaimsInvalid // Generic claims validation error
)

The errors that might occur when parsing and validating a token

View Source
const UnsafeAllowNoneSignatureType unsafeNoneMagicConstant = "none signing method allowed"

Variables

View Source
var (
	ErrNotECPublicKey  = errors.New("Key is not a valid ECDSA public key")
	ErrNotECPrivateKey = errors.New("Key is not a valid ECDSA private key")
)
View Source
var (
	ErrNotEdPrivateKey = errors.New("Key is not a valid Ed25519 private key")
	ErrNotEdPublicKey  = errors.New("Key is not a valid Ed25519 public key")
)
View Source
var (
	ErrInvalidKey      = errors.New("key is invalid")
	ErrInvalidKeyType  = errors.New("key is of invalid type")
	ErrHashUnavailable = errors.New("the requested hash function is unavailable")
)

Error constants

View Source
var (
	ErrKeyMustBePEMEncoded = errors.New("Invalid Key: Key must be a PEM encoded PKCS1 or PKCS8 key")
	ErrNotRSAPrivateKey    = errors.New("Key is not a valid RSA private key")
	ErrNotRSAPublicKey     = errors.New("Key is not a valid RSA public key")
)
View Source
var (
	// Sadly this is missing from crypto/ecdsa compared to crypto/rsa
	ErrECDSAVerification = errors.New("crypto/ecdsa: verification error")
)
View Source
var (
	ErrEd25519Verification = errors.New("ed25519: verification error")
)
View Source
var NoneSignatureTypeDisallowedError error
View Source
var SigningMethodNone *signingMethodNone

Implements the none signing method. This is required by the spec but you probably should never use it.

View Source
var TimeFunc = time.Now

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.

Functions

func DecodeSegment

func DecodeSegment(seg string) ([]byte, error)

Decode JWT specific base64url encoding with padding stripped

func EncodeSegment

func EncodeSegment(seg []byte) string

Encode JWT specific base64url encoding with padding stripped

func ParseECPrivateKeyFromPEM

func ParseECPrivateKeyFromPEM(key []byte) (*ecdsa.PrivateKey, error)

Parse PEM encoded Elliptic Curve Private Key Structure

func ParseECPublicKeyFromPEM

func ParseECPublicKeyFromPEM(key []byte) (*ecdsa.PublicKey, error)

Parse PEM encoded PKCS1 or PKCS8 public key

func ParseEdPrivateKeyFromPEM

func ParseEdPrivateKeyFromPEM(key []byte) (crypto.PrivateKey, error)

Parse PEM-encoded Edwards curve private key

func ParseEdPublicKeyFromPEM

func ParseEdPublicKeyFromPEM(key []byte) (crypto.PublicKey, error)

Parse PEM-encoded Edwards curve public key

func ParseRSAPrivateKeyFromPEM

func ParseRSAPrivateKeyFromPEM(key []byte) (*rsa.PrivateKey, error)

Parse PEM encoded PKCS1 or PKCS8 private key

func ParseRSAPrivateKeyFromPEMWithPassword

func ParseRSAPrivateKeyFromPEMWithPassword(key []byte, password string) (*rsa.PrivateKey, error)

Parse PEM encoded PKCS1 or PKCS8 private key protected with password

func ParseRSAPublicKeyFromPEM

func ParseRSAPublicKeyFromPEM(key []byte) (*rsa.PublicKey, error)

Parse PEM encoded PKCS1 or PKCS8 public key

func RegisterSigningMethod

func RegisterSigningMethod(alg string, f func() SigningMethod)

Register the "alg" name and a factory function for signing method. This is typically done during init() in the method's implementation

Types

type Claims

type Claims interface {
	Valid() error
}

For a type to be a Claims object, it must just have a Valid method that determines if the token is invalid for any supported reason

type Keyfunc

type Keyfunc func(*Token) (interface{}, error)

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 MapClaims

type MapClaims map[string]interface{}

Claims type that uses the map[string]interface{} for JSON decoding This is the default claims type if you don't supply one

func (MapClaims) Valid

func (m MapClaims) Valid() error

Validates time based claims "exp, iat, nbf". There is no accounting for clock skew. As well, if any of the above claims are not in the token, it will still be considered a valid claim.

func (MapClaims) VerifyAudience

func (m MapClaims) VerifyAudience(cmp string, req bool) bool

VerifyAudience Compares the aud claim against cmp. If required is false, this method will return true if the value matches or is unset

func (MapClaims) VerifyExpiresAt

func (m MapClaims) VerifyExpiresAt(cmp int64, req bool) bool

Compares the exp claim against cmp. If required is false, this method will return true if the value matches or is unset

func (MapClaims) VerifyIssuedAt

func (m MapClaims) VerifyIssuedAt(cmp int64, req bool) bool

Compares the iat claim against cmp. If required is false, this method will return true if the value matches or is unset

func (MapClaims) VerifyIssuer

func (m MapClaims) VerifyIssuer(cmp string, req bool) bool

Compares the iss claim against cmp. If required is false, this method will return true if the value matches or is unset

func (MapClaims) VerifyNotBefore

func (m MapClaims) VerifyNotBefore(cmp int64, req bool) bool

Compares the nbf claim against cmp. If required is false, this method will return true if the value matches or is unset

type Parser

type Parser struct {
	ValidMethods         []string // If populated, only these methods will be considered valid
	UseJSONNumber        bool     // Use JSON Number format in JSON decoder
	SkipClaimsValidation bool     // Skip claims validation during token parsing
}

func (*Parser) Parse

func (p *Parser) Parse(tokenString string, keyFunc Keyfunc) (*Token, error)

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 (*Parser) ParseUnverified

func (p *Parser) ParseUnverified(tokenString string, claims Claims) (token *Token, parts []string, err error)

WARNING: Don't use this method unless you know what you're doing

This method parses the token but doesn't validate the signature. It's only ever useful in cases where you know the signature is valid (because it has been checked previously in the stack) and you want to extract values from it.

func (*Parser) ParseWithClaims

func (p *Parser) ParseWithClaims(tokenString string, claims Claims, keyFunc Keyfunc) (*Token, error)

type SigningMethod

type SigningMethod interface {
	Verify(signingString, signature string, key interface{}) error // Returns nil if signature is valid
	Sign(signingString string, key interface{}) (string, error)    // Returns encoded signature or error
	Alg() string                                                   // returns the alg identifier for this method (example: 'HS256')
}

Implement SigningMethod to add new methods for signing or verifying tokens.

func GetSigningMethod

func GetSigningMethod(alg string) (method SigningMethod)

Get a signing method from an "alg" string

type SigningMethodECDSA

type SigningMethodECDSA struct {
	Name      string
	Hash      crypto.Hash
	KeySize   int
	CurveBits int
}

Implements the ECDSA family of signing methods signing methods Expects *ecdsa.PrivateKey for signing and *ecdsa.PublicKey for verification

var (
	SigningMethodES256 *SigningMethodECDSA
	SigningMethodES384 *SigningMethodECDSA
	SigningMethodES512 *SigningMethodECDSA
)

Specific instances for EC256 and company

func (*SigningMethodECDSA) Alg

func (m *SigningMethodECDSA) Alg() string

func (*SigningMethodECDSA) Sign

func (m *SigningMethodECDSA) Sign(signingString string, key interface{}) (string, error)

Implements the Sign method from SigningMethod For this signing method, key must be an ecdsa.PrivateKey struct

func (*SigningMethodECDSA) Verify

func (m *SigningMethodECDSA) Verify(signingString, signature string, key interface{}) error

Implements the Verify method from SigningMethod For this verify method, key must be an ecdsa.PublicKey struct

type SigningMethodEd25519

type SigningMethodEd25519 struct{}

Implements the EdDSA family Expects ed25519.PrivateKey for signing and ed25519.PublicKey for verification

var (
	SigningMethodEdDSA *SigningMethodEd25519
)

Specific instance for EdDSA

func (*SigningMethodEd25519) Alg

func (m *SigningMethodEd25519) Alg() string

func (*SigningMethodEd25519) Sign

func (m *SigningMethodEd25519) Sign(signingString string, key interface{}) (string, error)

Implements the Sign method from SigningMethod For this signing method, key must be an ed25519.PrivateKey

func (*SigningMethodEd25519) Verify

func (m *SigningMethodEd25519) Verify(signingString, signature string, key interface{}) error

Implements the Verify method from SigningMethod For this verify method, key must be an ed25519.PublicKey

type SigningMethodHMAC

type SigningMethodHMAC struct {
	Name string
	Hash crypto.Hash
}

Implements the HMAC-SHA family of signing methods signing methods Expects key type of []byte for both signing and validation

var (
	SigningMethodHS256  *SigningMethodHMAC
	SigningMethodHS384  *SigningMethodHMAC
	SigningMethodHS512  *SigningMethodHMAC
	ErrSignatureInvalid = errors.New("signature is invalid")
)

Specific instances for HS256 and company

func (*SigningMethodHMAC) Alg

func (m *SigningMethodHMAC) Alg() string

func (*SigningMethodHMAC) Sign

func (m *SigningMethodHMAC) Sign(signingString string, key interface{}) (string, error)

Implements the Sign method from SigningMethod for this signing method. Key must be []byte

func (*SigningMethodHMAC) Verify

func (m *SigningMethodHMAC) Verify(signingString, signature string, key interface{}) error

Verify the signature of HSXXX tokens. Returns nil if the signature is valid.

type SigningMethodRSA

type SigningMethodRSA struct {
	Name string
	Hash crypto.Hash
}

Implements the RSA family of signing methods signing methods Expects *rsa.PrivateKey for signing and *rsa.PublicKey for validation

var (
	SigningMethodRS256 *SigningMethodRSA
	SigningMethodRS384 *SigningMethodRSA
	SigningMethodRS512 *SigningMethodRSA
)

Specific instances for RS256 and company

func (*SigningMethodRSA) Alg

func (m *SigningMethodRSA) Alg() string

func (*SigningMethodRSA) Sign

func (m *SigningMethodRSA) Sign(signingString string, key interface{}) (string, error)

Implements the Sign method from SigningMethod For this signing method, must be an *rsa.PrivateKey structure.

func (*SigningMethodRSA) Verify

func (m *SigningMethodRSA) Verify(signingString, signature string, key interface{}) error

Implements the Verify method from SigningMethod For this signing method, must be an *rsa.PublicKey structure.

type SigningMethodRSAPSS

type SigningMethodRSAPSS struct {
	*SigningMethodRSA
	Options *rsa.PSSOptions
	// VerifyOptions is optional. If set overrides Options for rsa.VerifyPPS.
	// Used to accept tokens signed with rsa.PSSSaltLengthAuto, what doesn't follow
	// https://tools.ietf.org/html/rfc7518#section-3.5 but was used previously.
	// See https://github.com/dgrijalva/jwt-go/issues/285#issuecomment-437451244 for details.
	VerifyOptions *rsa.PSSOptions
}

Implements the RSAPSS family of signing methods signing methods

var (
	SigningMethodPS256 *SigningMethodRSAPSS
	SigningMethodPS384 *SigningMethodRSAPSS
	SigningMethodPS512 *SigningMethodRSAPSS
)

Specific instances for RS/PS and company.

func (*SigningMethodRSAPSS) Sign

func (m *SigningMethodRSAPSS) Sign(signingString string, key interface{}) (string, error)

Implements the Sign method from SigningMethod For this signing method, key must be an rsa.PrivateKey struct

func (*SigningMethodRSAPSS) Verify

func (m *SigningMethodRSAPSS) Verify(signingString, signature string, key interface{}) error

Implements the Verify method from SigningMethod For this verify method, key must be an rsa.PublicKey struct

type StandardClaims

type StandardClaims struct {
	Audience  string `json:"aud,omitempty"`
	ExpiresAt int64  `json:"exp,omitempty"`
	Id        string `json:"jti,omitempty"`
	IssuedAt  int64  `json:"iat,omitempty"`
	Issuer    string `json:"iss,omitempty"`
	NotBefore int64  `json:"nbf,omitempty"`
	Subject   string `json:"sub,omitempty"`
}

Structured version of Claims Section, as referenced at https://tools.ietf.org/html/rfc7519#section-4.1 See examples for how to use this with your own claim types

func (StandardClaims) Valid

func (c StandardClaims) Valid() error

Validates time based claims "exp, iat, nbf". There is no accounting for clock skew. As well, if any of the above claims are not in the token, it will still be considered a valid claim.

func (*StandardClaims) VerifyAudience

func (c *StandardClaims) VerifyAudience(cmp string, req bool) bool

Compares the aud claim against cmp. If required is false, this method will return true if the value matches or is unset

func (*StandardClaims) VerifyExpiresAt

func (c *StandardClaims) VerifyExpiresAt(cmp int64, req bool) bool

Compares the exp claim against cmp. If required is false, this method will return true if the value matches or is unset

func (*StandardClaims) VerifyIssuedAt

func (c *StandardClaims) VerifyIssuedAt(cmp int64, req bool) bool

Compares the iat claim against cmp. If required is false, this method will return true if the value matches or is unset

func (*StandardClaims) VerifyIssuer

func (c *StandardClaims) VerifyIssuer(cmp string, req bool) bool

Compares the iss claim against cmp. If required is false, this method will return true if the value matches or is unset

func (*StandardClaims) VerifyNotBefore

func (c *StandardClaims) VerifyNotBefore(cmp int64, req bool) bool

Compares the nbf claim against cmp. If required is false, this method will return true if the value matches or is unset

type 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
}

A JWT Token. Different fields will be used depending on whether you're creating or parsing/verifying a token.

func New

func New(method SigningMethod) *Token

Create a new Token. Takes a signing method

Example (Hmac)

Example creating, signing, and encoding a JWT token using the HMAC signing method

package main

import (
	"fmt"
	"time"

	"github.com/golang-jwt/jwt"
)

// For HMAC signing method, the key can be any []byte. It is recommended to generate
// a key using crypto/rand or something equivalent. You need the same key for signing
// and validating.
var hmacSampleSecret []byte

func main() {
	// Create a new token object, specifying signing method and the claims
	// you would like it to contain.
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
		"foo": "bar",
		"nbf": time.Date(2015, 10, 10, 12, 0, 0, 0, time.UTC).Unix(),
	})

	// Sign and get the complete encoded token as a string using the secret
	tokenString, err := token.SignedString(hmacSampleSecret)

	fmt.Println(tokenString, err)
}
Output:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJuYmYiOjE0NDQ0Nzg0MDB9.u1riaD1rW97opCoAuRCTy4w58Br-Zk-bh7vLiRIsrpU <nil>

func NewWithClaims

func NewWithClaims(method SigningMethod, claims Claims) *Token
Example (CustomClaimsType)

Example creating a token using a custom claims type. The StandardClaim is embedded in the custom type to allow for easy encoding, parsing and validation of standard claims.

package main

import (
	"fmt"

	"github.com/golang-jwt/jwt"
)

func main() {
	mySigningKey := []byte("AllYourBase")

	type MyCustomClaims struct {
		Foo string `json:"foo"`
		jwt.StandardClaims
	}

	// Create the Claims
	claims := MyCustomClaims{
		"bar",
		jwt.StandardClaims{
			ExpiresAt: 15000,
			Issuer:    "test",
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	ss, err := token.SignedString(mySigningKey)
	fmt.Printf("%v %v", ss, err)
}
Output:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJleHAiOjE1MDAwLCJpc3MiOiJ0ZXN0In0.HE7fK0xOQwFEr4WDgRWj4teRPZ6i3GLwD5YCm6Pwu_c <nil>
Example (StandardClaims)

Example (atypical) using the StandardClaims type by itself to parse a token. The StandardClaims type is designed to be embedded into your custom types to provide standard validation features. You can use it alone, but there's no way to retrieve other fields after parsing. See the CustomClaimsType example for intended usage.

package main

import (
	"fmt"

	"github.com/golang-jwt/jwt"
)

func main() {
	mySigningKey := []byte("AllYourBase")

	// Create the Claims
	claims := &jwt.StandardClaims{
		ExpiresAt: 15000,
		Issuer:    "test",
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	ss, err := token.SignedString(mySigningKey)
	fmt.Printf("%v %v", ss, err)
}
Output:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE1MDAwLCJpc3MiOiJ0ZXN0In0.QsODzZu3lUZMVdhbO76u3Jv02iYCvEHcYVUI1kOWEU0 <nil>

func Parse

func Parse(tokenString string, keyFunc Keyfunc) (*Token, error)

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

Example (ErrorChecking)

An example of parsing the error types using bitfield checks

package main

import (
	"fmt"

	"github.com/golang-jwt/jwt"
)

func main() {
	// Token from another example.  This token is expired
	var tokenString = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJleHAiOjE1MDAwLCJpc3MiOiJ0ZXN0In0.HE7fK0xOQwFEr4WDgRWj4teRPZ6i3GLwD5YCm6Pwu_c"

	token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
		return []byte("AllYourBase"), nil
	})

	if token.Valid {
		fmt.Println("You look nice today")
	} else if ve, ok := err.(*jwt.ValidationError); ok {
		if ve.Errors&jwt.ValidationErrorMalformed != 0 {
			fmt.Println("That's not even a token")
		} else if ve.Errors&(jwt.ValidationErrorExpired|jwt.ValidationErrorNotValidYet) != 0 {
			// Token is either expired or not active yet
			fmt.Println("Timing is everything")
		} else {
			fmt.Println("Couldn't handle this token:", err)
		}
	} else {
		fmt.Println("Couldn't handle this token:", err)
	}

}
Output:

Timing is everything
Example (Hmac)

Example parsing and validating a token using the HMAC signing method

package main

import (
	"fmt"

	"github.com/golang-jwt/jwt"
)

// For HMAC signing method, the key can be any []byte. It is recommended to generate
// a key using crypto/rand or something equivalent. You need the same key for signing
// and validating.
var hmacSampleSecret []byte

func main() {
	// sample token string taken from the New example
	tokenString := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJuYmYiOjE0NDQ0Nzg0MDB9.u1riaD1rW97opCoAuRCTy4w58Br-Zk-bh7vLiRIsrpU"

	// Parse takes the token string and a function for looking up the key. The latter is especially
	// useful if you use multiple keys for your application.  The standard is to use 'kid' in the
	// head of the token to identify which key to use, but the parsed token (head and claims) is provided
	// to the callback, providing flexibility.
	token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
		// Don't forget to validate the alg is what you expect:
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("Unexpected signing method: %v", token.Header["alg"])
		}

		// hmacSampleSecret is a []byte containing your secret, e.g. []byte("my_secret_key")
		return hmacSampleSecret, nil
	})

	if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
		fmt.Println(claims["foo"], claims["nbf"])
	} else {
		fmt.Println(err)
	}

}
Output:

bar 1.4444784e+09

func ParseWithClaims

func ParseWithClaims(tokenString string, claims Claims, keyFunc Keyfunc) (*Token, error)
Example (CustomClaimsType)

Example creating a token using a custom claims type. The StandardClaim is embedded in the custom type to allow for easy encoding, parsing and validation of standard claims.

package main

import (
	"fmt"
	"time"

	"github.com/golang-jwt/jwt"
)

func main() {
	tokenString := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJleHAiOjE1MDAwLCJpc3MiOiJ0ZXN0In0.HE7fK0xOQwFEr4WDgRWj4teRPZ6i3GLwD5YCm6Pwu_c"

	type MyCustomClaims struct {
		Foo string `json:"foo"`
		jwt.StandardClaims
	}

	// sample token is expired.  override time so it parses as valid
	at(time.Unix(0, 0), func() {
		token, err := jwt.ParseWithClaims(tokenString, &MyCustomClaims{}, func(token *jwt.Token) (interface{}, error) {
			return []byte("AllYourBase"), nil
		})

		if claims, ok := token.Claims.(*MyCustomClaims); ok && token.Valid {
			fmt.Printf("%v %v", claims.Foo, claims.StandardClaims.ExpiresAt)
		} else {
			fmt.Println(err)
		}
	})

}

// Override time value for tests.  Restore default value after.
func at(t time.Time, f func()) {
	jwt.TimeFunc = func() time.Time {
		return t
	}
	f()
	jwt.TimeFunc = time.Now
}
Output:

bar 15000

func (*Token) SignedString

func (t *Token) SignedString(key interface{}) (string, error)

Get the complete, signed token

func (*Token) SigningString

func (t *Token) SigningString() (string, error)

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.

type ValidationError

type ValidationError struct {
	Inner  error  // stores the error returned by external dependencies, i.e.: KeyFunc
	Errors uint32 // bitfield.  see ValidationError... constants
	// contains filtered or unexported fields
}

The error from Parse if token is not valid

func NewValidationError

func NewValidationError(errorText string, errorFlags uint32) *ValidationError

Helper for constructing a ValidationError with a string error message

func (ValidationError) Error

func (e ValidationError) Error() string

Validation error is an error type

Directories

Path Synopsis
cmd
jwt
A useful example app.
A useful example app.
Utility package for extracting JWT tokens from HTTP requests.
Utility package for extracting JWT tokens from HTTP requests.

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
t or T : Toggle theme light dark auto