jwt

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README

jwt-go

build Go Reference Coverage Status

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

Starting with v4.0.0 this project adds Go module support, but maintains backward compatibility with older v3.x.y tags and upstream github.com/dgrijalva/jwt-go. See the MIGRATION_GUIDE.md for more information. Version v5.0.0 introduces major improvements to the validation of tokens, but is not entirely backward compatible.

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.

SECURITY NOTICE: Some older versions of Go have a security issue in the crypto/elliptic. The 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 to 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 that 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.

Installation Guidelines

  1. To install the jwt package, you first need to have Go installed, then you can use the command below to add jwt-go as a dependency in your Go program.
go get -u github.com/golang-jwt/jwt/v5
  1. Import it in your code:
import "github.com/golang-jwt/jwt/v5"

Usage

A detailed usage guide, including how to sign and verify tokens can be found on our documentation website.

Examples

See the project documentation for examples of usage:

Compliance

This library was last reviewed to comply with RFC 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 backward-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.

BREAKING CHANGES: A full list of breaking changes is available in VERSION_HISTORY.md. See MIGRATION_GUIDE.md for more information on updating your code.

Extensions

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

A common use case would be integrating with different 3rd party signature providers, like key management services from various cloud providers or Hardware Security Modules (HSMs) or to implement additional standards.

Extension Purpose Repo
GCP Integrates with multiple Google Cloud Platform signing tools (AppEngine, IAM API, Cloud KMS) https://github.com/someone1/gcp-jwt-go
AWS Integrates with AWS Key Management Service, KMS https://github.com/matelang/jwt-go-aws-kms
JWKS Provides support for JWKS (RFC 7517) as a jwt.Keyfunc https://github.com/MicahParks/keyfunc

Disclaimer: Unless otherwise specified, these integrations are maintained by third parties and should not be considered as a primary offer by any of the mentioned cloud providers

More

Go package documentation can be found on pkg.go.dev. Additional documentation can be found on our project page.

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.

golang-jwt incorporates a modified version of the JWT logo, which is distributed under the terms of the MIT License.

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) 
// 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"},
})
fatal(err)

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

// Read the token out of the response body
buf, err := io.ReadAll(res.Body)
fatal(err)
res.Body.Close()
tokenString := strings.TrimSpace(string(buf))

// 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) 
// 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, err := io.ReadAll(res.Body)
fatal(err)
res.Body.Close()
fmt.Printf("%s", buf)

Output:

Welcome, foo

Index

Examples

Constants

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")
	ErrTokenMalformed            = errors.New("token is malformed")
	ErrTokenUnverifiable         = errors.New("token is unverifiable")
	ErrTokenSignatureInvalid     = errors.New("token signature is invalid")
	ErrTokenRequiredClaimMissing = errors.New("token is missing required claim")
	ErrTokenInvalidAudience      = errors.New("token has invalid audience")
	ErrTokenExpired              = errors.New("token is expired")
	ErrTokenUsedBeforeIssued     = errors.New("token used before issued")
	ErrTokenInvalidIssuer        = errors.New("token has invalid issuer")
	ErrTokenInvalidSubject       = errors.New("token has invalid subject")
	ErrTokenNotValidYet          = errors.New("token is not valid yet")
	ErrTokenInvalidId            = errors.New("token has invalid id")
	ErrTokenInvalidClaims        = errors.New("token has invalid claims")
	ErrInvalidType               = errors.New("invalid type for claim")
)
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 MarshalSingleStringAsArray = true

MarshalSingleStringAsArray modifies the behavior of the ClaimStrings type, especially its MarshalJSON function.

If it is set to true (the default), it will always serialize the type as an array of strings, even if it just contains one element, defaulting to the behavior of the underlying []string. If it is set to false, it will serialize to a single string, if it contains one element. Otherwise, it will serialize to an array of strings.

View Source 
var NoneSignatureTypeDisallowedError error
View Source 
var SigningMethodNone *signingMethodNone

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

View Source 
var TimePrecision = time.Second

TimePrecision sets the precision of times and dates within this library. This has an influence on the precision of times when comparing expiry or other related time fields. Furthermore, it is also the precision of times when serializing.

For backwards compatibility the default precision is set to seconds, so that no fractional timestamps are generated.

Functions

func GetAlgorithms 

func GetAlgorithms() (algs []string)

GetAlgorithms returns a list of registered "alg" names

func ParseECPrivateKeyFromPEM 

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

ParseECPrivateKeyFromPEM parses a PEM encoded Elliptic Curve Private Key Structure

func ParseECPublicKeyFromPEM 

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

ParseECPublicKeyFromPEM parses a PEM encoded PKCS1 or PKCS8 public key

func ParseEdPrivateKeyFromPEM 

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

ParseEdPrivateKeyFromPEM parses a PEM-encoded Edwards curve private key

func ParseEdPublicKeyFromPEM 

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

ParseEdPublicKeyFromPEM parses a PEM-encoded Edwards curve public key

func ParseRSAPrivateKeyFromPEM 

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

ParseRSAPrivateKeyFromPEM parses a PEM encoded PKCS1 or PKCS8 private key

func ParseRSAPrivateKeyFromPEMWithPassword deprecated 

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

ParseRSAPrivateKeyFromPEMWithPassword parses a PEM encoded PKCS1 or PKCS8 private key protected with password

Deprecated: This function is deprecated and should not be used anymore. It uses the deprecated x509.DecryptPEMBlock function, which was deprecated since RFC 1423 is regarded insecure by design. Unfortunately, there is no alternative in the Go standard library for now. See https://github.com/golang/go/issues/8860.

func ParseRSAPublicKeyFromPEM 

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

ParseRSAPublicKeyFromPEM parses a certificate or a PEM encoded PKCS1 or PKIX public key

func RegisterSigningMethod 

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

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

Types

type ClaimStrings 

type ClaimStrings []string

ClaimStrings is basically just a slice of strings, but it can be either serialized from a string array or just a string. This type is necessary, since the "aud" claim can either be a single string or an array.

func (ClaimStrings) MarshalJSON 

func (s ClaimStrings) MarshalJSON() (b []byte, err error)

func (*ClaimStrings) UnmarshalJSON 

func (s *ClaimStrings) UnmarshalJSON(data []byte) (err error)

type Claims 

type Claims interface {
	GetExpirationTime() (*NumericDate, error)
	GetIssuedAt() (*NumericDate, error)
	GetNotBefore() (*NumericDate, error)
	GetIssuer() (string, error)
	GetSubject() (string, error)
	GetAudience() (ClaimStrings, error)
}

Claims represent any form of a JWT Claims Set according to https://datatracker.ietf.org/doc/html/rfc7519#section-4. In order to have a common basis for validation, it is required that an implementation is able to supply at least the claim names provided in https://datatracker.ietf.org/doc/html/rfc7519#section-4.1 namely `exp`, `iat`, `nbf`, `iss`, `sub` and `aud`.

type ClaimsValidator 

type ClaimsValidator interface {
	Claims
	Validate() error
}

ClaimsValidator is an interface that can be implemented by custom claims who wish to execute any additional claims validation based on application-specific logic. The Validate function is then executed in addition to the regular claims validation and any error returned is appended to the final validation result. 

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

func (m MyCustomClaims) Validate() error {
    if m.Foo != "bar" {
        return errors.New("must be foobar")
    }
    return nil
}

type Keyfunc 

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

Keyfunc will be used by the Parse methods as a 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.

The returned interface{} may be a single key or a VerificationKeySet containing multiple keys.

type MapClaims 

type MapClaims map[string]interface{}

MapClaims is a 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) GetAudience 

func (m MapClaims) GetAudience() (ClaimStrings, error)

GetAudience implements the Claims interface.

func (MapClaims) GetExpirationTime 

func (m MapClaims) GetExpirationTime() (*NumericDate, error)

GetExpirationTime implements the Claims interface.

func (MapClaims) GetIssuedAt 

func (m MapClaims) GetIssuedAt() (*NumericDate, error)

GetIssuedAt implements the Claims interface.

func (MapClaims) GetIssuer 

func (m MapClaims) GetIssuer() (string, error)

GetIssuer implements the Claims interface.

func (MapClaims) GetNotBefore 

func (m MapClaims) GetNotBefore() (*NumericDate, error)

GetNotBefore implements the Claims interface.

func (MapClaims) GetSubject 

func (m MapClaims) GetSubject() (string, error)

GetSubject implements the Claims interface.

type NumericDate 

type NumericDate struct {
	time.Time
}

NumericDate represents a JSON numeric date value, as referenced at https://datatracker.ietf.org/doc/html/rfc7519#section-2.

func NewNumericDate 

func NewNumericDate(t time.Time) *NumericDate

NewNumericDate constructs a new *NumericDate from a standard library time.Time struct. It will truncate the timestamp according to the precision specified in TimePrecision.

func (NumericDate) MarshalJSON 

func (date NumericDate) MarshalJSON() (b []byte, err error)

MarshalJSON is an implementation of the json.RawMessage interface and serializes the UNIX epoch represented in NumericDate to a byte array, using the precision specified in TimePrecision.

func (*NumericDate) UnmarshalJSON 

func (date *NumericDate) UnmarshalJSON(b []byte) (err error)

UnmarshalJSON is an implementation of the json.RawMessage interface and deserializes a NumericDate from a JSON representation, i.e. a json.Number. This number represents an UNIX epoch with either integer or non-integer seconds.

type Parser 

type Parser struct {
	// contains filtered or unexported fields
}

func NewParser 

func NewParser(options ...ParserOption) *Parser

NewParser creates a new Parser with the specified options

func (*Parser) DecodeSegment 

func (p *Parser) DecodeSegment(seg string) ([]byte, error)

DecodeSegment decodes a JWT specific base64url encoding. This function will take into account whether the Parser is configured with additional options, such as WithStrictDecoding or WithPaddingAllowed.

func (*Parser) Parse 

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

Parse parses, validates, verifies the signature and returns the parsed token. keyFunc will receive the parsed token and should return the key for validating.

func (*Parser) ParseUnverified 

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

ParseUnverified parses the token but doesn't validate the signature.

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

It's only ever useful in cases where you know the signature is valid (since it has already been or will be checked elsewhere 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)

ParseWithClaims parses, validates, and verifies like Parse, but supplies a default object implementing the Claims interface. This provides default values which can be overridden and allows a caller to use their own type, rather than the default MapClaims implementation of Claims.

Note: If you provide a custom claim implementation that embeds one of the standard claims (such as RegisteredClaims), make sure that a) you either embed a non-pointer version of the claims or b) if you are using a pointer, allocate the proper memory for it before passing in the overall claims, otherwise you might run into a panic.

type ParserOption 

type ParserOption func(*Parser)

ParserOption is used to implement functional-style options that modify the behavior of the parser. To add new options, just create a function (ideally beginning with With or Without) that returns an anonymous function that takes a *Parser type as input and manipulates its configuration accordingly.

func WithAudience 

func WithAudience(aud string) ParserOption

WithAudience configures the validator to require the specified audience in the `aud` claim. Validation will fail if the audience is not listed in the token or the `aud` claim is missing.

NOTE: While the `aud` claim is OPTIONAL in a JWT, the handling of it is application-specific. Since this validation API is helping developers in writing secure application, we decided to REQUIRE the existence of the claim, if an audience is expected.

func WithExpirationRequired 

func WithExpirationRequired() ParserOption

WithExpirationRequired returns the ParserOption to make exp claim required. By default exp claim is optional.

func WithIssuedAt 

func WithIssuedAt() ParserOption

WithIssuedAt returns the ParserOption to enable verification of issued-at.

func WithIssuer 

func WithIssuer(iss string) ParserOption

WithIssuer configures the validator to require the specified issuer in the `iss` claim. Validation will fail if a different issuer is specified in the token or the `iss` claim is missing.

NOTE: While the `iss` claim is OPTIONAL in a JWT, the handling of it is application-specific. Since this validation API is helping developers in writing secure application, we decided to REQUIRE the existence of the claim, if an issuer is expected.

func WithJSONNumber 

func WithJSONNumber() ParserOption

WithJSONNumber is an option to configure the underlying JSON parser with UseNumber.

func WithLeeway 

func WithLeeway(leeway time.Duration) ParserOption

WithLeeway returns the ParserOption for specifying the leeway window.

func WithPaddingAllowed 

func WithPaddingAllowed() ParserOption

WithPaddingAllowed will enable the codec used for decoding JWTs to allow padding. Note that the JWS RFC7515 states that the tokens will utilize a Base64url encoding with no padding. Unfortunately, some implementations of JWT are producing non-standard tokens, and thus require support for decoding.

func WithStrictDecoding 

func WithStrictDecoding() ParserOption

WithStrictDecoding will switch the codec used for decoding JWTs into strict mode. In this mode, the decoder requires that trailing padding bits are zero, as described in RFC 4648 section 3.5.

func WithSubject 

func WithSubject(sub string) ParserOption

WithSubject configures the validator to require the specified subject in the `sub` claim. Validation will fail if a different subject is specified in the token or the `sub` claim is missing.

NOTE: While the `sub` claim is OPTIONAL in a JWT, the handling of it is application-specific. Since this validation API is helping developers in writing secure application, we decided to REQUIRE the existence of the claim, if a subject is expected.

func WithTimeFunc 

func WithTimeFunc(f func() time.Time) ParserOption

WithTimeFunc returns the ParserOption for specifying the time func. The primary use-case for this is testing. If you are looking for a way to account for clock-skew, WithLeeway should be used instead.

func WithValidMethods 

func WithValidMethods(methods []string) ParserOption

WithValidMethods is an option to supply algorithm methods that the parser will check. Only those methods will be considered valid. It is heavily encouraged to use this option in order to prevent attacks such as https://auth0.com/blog/critical-vulnerabilities-in-json-web-token-libraries/.

func WithoutClaimsValidation 

func WithoutClaimsValidation() ParserOption

WithoutClaimsValidation is an option to disable claims validation. This option should only be used if you exactly know what you are doing.

type RegisteredClaims 

type RegisteredClaims struct {
	// the `iss` (Issuer) claim. See https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.1
	Issuer string `json:"iss,omitempty"`

	// the `sub` (Subject) claim. See https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.2
	Subject string `json:"sub,omitempty"`

	// the `aud` (Audience) claim. See https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.3
	Audience ClaimStrings `json:"aud,omitempty"`

	// the `exp` (Expiration Time) claim. See https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.4
	ExpiresAt *NumericDate `json:"exp,omitempty"`

	// the `nbf` (Not Before) claim. See https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.5
	NotBefore *NumericDate `json:"nbf,omitempty"`

	// the `iat` (Issued At) claim. See https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.6
	IssuedAt *NumericDate `json:"iat,omitempty"`

	// the `jti` (JWT ID) claim. See https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.7
	ID string `json:"jti,omitempty"`
}

RegisteredClaims are a structured version of the JWT Claims Set, restricted to Registered Claim Names, as referenced at https://datatracker.ietf.org/doc/html/rfc7519#section-4.1

This type can be used on its own, but then additional private and public claims embedded in the JWT will not be parsed. The typical use-case therefore is to embedded this in a user-defined claim type.

See examples for how to use this with your own claim types.

func (RegisteredClaims) GetAudience 

func (c RegisteredClaims) GetAudience() (ClaimStrings, error)

GetAudience implements the Claims interface.

func (RegisteredClaims) GetExpirationTime 

func (c RegisteredClaims) GetExpirationTime() (*NumericDate, error)

GetExpirationTime implements the Claims interface.

func (RegisteredClaims) GetIssuedAt 

func (c RegisteredClaims) GetIssuedAt() (*NumericDate, error)

GetIssuedAt implements the Claims interface.

func (RegisteredClaims) GetIssuer 

func (c RegisteredClaims) GetIssuer() (string, error)

GetIssuer implements the Claims interface.

func (RegisteredClaims) GetNotBefore 

func (c RegisteredClaims) GetNotBefore() (*NumericDate, error)

GetNotBefore implements the Claims interface.

func (RegisteredClaims) GetSubject 

func (c RegisteredClaims) GetSubject() (string, error)

GetSubject implements the Claims interface.

type SigningMethod 

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

SigningMethod can be used add new methods for signing or verifying tokens. It takes a decoded signature as an input in the Verify function and produces a signature in Sign. The signature is then usually base64 encoded as part of a JWT.

func GetSigningMethod 

func GetSigningMethod(alg string) (method SigningMethod)

GetSigningMethod retrieves a signing method from an "alg" string

type SigningMethodECDSA 

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

SigningMethodECDSA implements the ECDSA family of 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{}) ([]byte, error)

Sign implements token signing for the SigningMethod. For this signing method, key must be an ecdsa.PrivateKey struct

func (*SigningMethodECDSA) Verify 

func (m *SigningMethodECDSA) Verify(signingString string, sig []byte, key interface{}) error

Verify implements token verification for the SigningMethod. For this verify method, key must be an ecdsa.PublicKey struct

type SigningMethodEd25519 

type SigningMethodEd25519 struct{}

SigningMethodEd25519 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{}) ([]byte, error)

Sign implements token signing for the SigningMethod. For this signing method, key must be an ed25519.PrivateKey

func (*SigningMethodEd25519) Verify 

func (m *SigningMethodEd25519) Verify(signingString string, sig []byte, key interface{}) error

Verify implements token verification for the SigningMethod. For this verify method, key must be an ed25519.PublicKey

type SigningMethodHMAC 

type SigningMethodHMAC struct {
	Name string
	Hash crypto.Hash
}

SigningMethodHMAC implements the HMAC-SHA family of 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{}) ([]byte, error)

Sign implements token signing for the SigningMethod. Key must be []byte.

Note it is not advised to provide a []byte which was converted from a 'human readable' string using a subset of ASCII characters. To maximize entropy, you should ideally be providing a []byte key which was produced from a cryptographically random source, e.g. crypto/rand. Additional information about this, and why we intentionally are not supporting string as a key can be found on our usage guide https://golang-jwt.github.io/jwt/usage/signing_methods/.

func (*SigningMethodHMAC) Verify 

func (m *SigningMethodHMAC) Verify(signingString string, sig []byte, key interface{}) error

Verify implements token verification for the SigningMethod. Returns nil if the signature is valid. Key must be []byte.

Note it is not advised to provide a []byte which was converted from a 'human readable' string using a subset of ASCII characters. To maximize entropy, you should ideally be providing a []byte key which was produced from a cryptographically random source, e.g. crypto/rand. Additional information about this, and why we intentionally are not supporting string as a key can be found on our usage guide https://golang-jwt.github.io/jwt/usage/signing_methods/#signing-methods-and-key-types.

type SigningMethodRSA 

type SigningMethodRSA struct {
	Name string
	Hash crypto.Hash
}

SigningMethodRSA implements the RSA family of 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{}) ([]byte, error)

Sign implements token signing for the SigningMethod For this signing method, must be an *rsa.PrivateKey structure.

func (*SigningMethodRSA) Verify 

func (m *SigningMethodRSA) Verify(signingString string, sig []byte, key interface{}) error

Verify implements token verification for the 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
}

SigningMethodRSAPSS 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{}) ([]byte, error)

Sign implements token signing for the SigningMethod. For this signing method, key must be an rsa.PrivateKey struct

func (*SigningMethodRSAPSS) Verify 

func (m *SigningMethodRSAPSS) Verify(signingString string, sig []byte, key interface{}) error

Verify implements token verification for the SigningMethod. For this verify method, key must be an rsa.PublicKey struct

type Token 

type Token struct {
	Raw       string                 // Raw contains the raw token.  Populated when you [Parse] a token
	Method    SigningMethod          // Method is the signing method used or to be used
	Header    map[string]interface{} // Header is the first segment of the token in decoded form
	Claims    Claims                 // Claims is the second segment of the token in decoded form
	Signature []byte                 // Signature is the third segment of the token in decoded form.  Populated when you Parse a token
	Valid     bool                   // Valid specifies if the token is valid.  Populated when you Parse/Verify a token
}

Token represents 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, opts ...TokenOption) *Token

New creates a new Token with the specified signing method and an empty map of claims. Additional options can be specified, but are currently unused.

Example (Hmac)

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

// 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, opts ...TokenOption) *Token

NewWithClaims creates a new Token with the specified signing method and claims. Additional options can be specified, but are currently unused.

Example (CustomClaimsType)

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

mySigningKey := []byte("AllYourBase")

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

// Create claims with multiple fields populated
claims := MyCustomClaims{
	"bar",
	jwt.RegisteredClaims{
		// A usual scenario is to set the expiration time relative to the current time
		ExpiresAt: jwt.NewNumericDate(time.Now().Add(24 * time.Hour)),
		IssuedAt:  jwt.NewNumericDate(time.Now()),
		NotBefore: jwt.NewNumericDate(time.Now()),
		Issuer:    "test",
		Subject:   "somebody",
		ID:        "1",
		Audience:  []string{"somebody_else"},
	},
}

fmt.Printf("foo: %v\n", claims.Foo)

// Create claims while leaving out some of the optional fields
claims = MyCustomClaims{
	"bar",
	jwt.RegisteredClaims{
		// Also fixed dates can be used for the NumericDate
		ExpiresAt: jwt.NewNumericDate(time.Unix(1516239022, 0)),
		Issuer:    "test",
	},
}

token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
ss, err := token.SignedString(mySigningKey)
fmt.Println(ss, err)

Output:

foo: bar
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJpc3MiOiJ0ZXN0IiwiZXhwIjoxNTE2MjM5MDIyfQ.xVuY2FZ_MRXMIEgVQ7J-TFtaucVFRXUzHm9LmV41goM <nil>
Example (RegisteredClaims)

Example (atypical) using the RegisteredClaims type by itself to parse a token. The RegisteredClaims 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. 

mySigningKey := []byte("AllYourBase")

// Create the Claims
claims := &jwt.RegisteredClaims{
	ExpiresAt: jwt.NewNumericDate(time.Unix(1516239022, 0)),
	Issuer:    "test",
}

token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
ss, err := token.SignedString(mySigningKey)
fmt.Println(ss, err)

Output:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJ0ZXN0IiwiZXhwIjoxNTE2MjM5MDIyfQ.0XN_1Tpp9FszFOonIBpwha0c_SfnNI22DhTnjMshPg8 <nil>

func Parse 

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

Parse parses, validates, verifies the signature and returns the parsed token. keyFunc will receive the parsed token and should return the cryptographic key for verifying the signature. The caller is strongly encouraged to set the WithValidMethods option to validate the 'alg' claim in the token matches the expected algorithm. For more details about the importance of validating the 'alg' claim, see https://auth0.com/blog/critical-vulnerabilities-in-json-web-token-libraries/

Example (ErrorChecking)

An example of parsing the error types using errors.Is. 

// 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
})

switch {
case token.Valid:
	fmt.Println("You look nice today")
case errors.Is(err, jwt.ErrTokenMalformed):
	fmt.Println("That's not even a token")
case errors.Is(err, jwt.ErrTokenSignatureInvalid):
	// Invalid signature
	fmt.Println("Invalid signature")
case errors.Is(err, jwt.ErrTokenExpired) || errors.Is(err, jwt.ErrTokenNotValidYet):
	// Token is either expired or not active yet
	fmt.Println("Timing is everything")
default:
	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 

// 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 err != nil {
	log.Fatal(err)
}

if claims, ok := token.Claims.(jwt.MapClaims); ok {
	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, options ...ParserOption) (*Token, error)

ParseWithClaims is a shortcut for NewParser().ParseWithClaims().

Note: If you provide a custom claim implementation that embeds one of the standard claims (such as RegisteredClaims), make sure that a) you either embed a non-pointer version of the claims or b) if you are using a pointer, allocate the proper memory for it before passing in the overall claims, otherwise you might run into a panic.

Example (CustomClaimsType)

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

tokenString := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJpc3MiOiJ0ZXN0IiwiYXVkIjoic2luZ2xlIn0.QAWg1vGvnqRuCFTMcPkjZljXHh8U3L_qUjszOtQbeaA"

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

token, err := jwt.ParseWithClaims(tokenString, &MyCustomClaims{}, func(token *jwt.Token) (interface{}, error) {
	return []byte("AllYourBase"), nil
})
if err != nil {
	log.Fatal(err)
} else if claims, ok := token.Claims.(*MyCustomClaims); ok {
	fmt.Println(claims.Foo, claims.RegisteredClaims.Issuer)
} else {
	log.Fatal("unknown claims type, cannot proceed")
}

Output:

bar test
Example (CustomValidation)

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

tokenString := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJpc3MiOiJ0ZXN0IiwiYXVkIjoic2luZ2xlIn0.QAWg1vGvnqRuCFTMcPkjZljXHh8U3L_qUjszOtQbeaA"

token, err := jwt.ParseWithClaims(tokenString, &MyCustomClaims{}, func(token *jwt.Token) (interface{}, error) {
	return []byte("AllYourBase"), nil
}, jwt.WithLeeway(5*time.Second))
if err != nil {
	log.Fatal(err)
} else if claims, ok := token.Claims.(*MyCustomClaims); ok {
	fmt.Println(claims.Foo, claims.RegisteredClaims.Issuer)
} else {
	log.Fatal("unknown claims type, cannot proceed")
}

Output:

bar test
Example (ValidationOptions)

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

tokenString := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJpc3MiOiJ0ZXN0IiwiYXVkIjoic2luZ2xlIn0.QAWg1vGvnqRuCFTMcPkjZljXHh8U3L_qUjszOtQbeaA"

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

token, err := jwt.ParseWithClaims(tokenString, &MyCustomClaims{}, func(token *jwt.Token) (interface{}, error) {
	return []byte("AllYourBase"), nil
}, jwt.WithLeeway(5*time.Second))
if err != nil {
	log.Fatal(err)
} else if claims, ok := token.Claims.(*MyCustomClaims); ok {
	fmt.Println(claims.Foo, claims.RegisteredClaims.Issuer)
} else {
	log.Fatal("unknown claims type, cannot proceed")
}

Output:

bar test

func (*Token) EncodeSegment 

func (*Token) EncodeSegment(seg []byte) string

EncodeSegment encodes a JWT specific base64url encoding with padding stripped. In the future, this function might take into account a TokenOption. Therefore, this function exists as a method of Token, rather than a global function.

func (*Token) SignedString 

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

SignedString creates and returns a complete, signed JWT. The token is signed using the SigningMethod specified in the token. Please refer to https://golang-jwt.github.io/jwt/usage/signing_methods/#signing-methods-and-key-types for an overview of the different signing methods and their respective key types.

func (*Token) SigningString 

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

SigningString generates 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 TokenOption 

type TokenOption func(*Token)

TokenOption is a reserved type, which provides some forward compatibility, if we ever want to introduce token creation-related options.

type Validator 

type Validator struct {
	// contains filtered or unexported fields
}

Validator is the core of the new Validation API. It is automatically used by a Parser during parsing and can be modified with various parser options.

The NewValidator function should be used to create an instance of this struct.

func NewValidator 

func NewValidator(opts ...ParserOption) *Validator

NewValidator can be used to create a stand-alone validator with the supplied options. This validator can then be used to validate already parsed claims.

Note: Under normal circumstances, explicitly creating a validator is not needed and can potentially be dangerous; instead functions of the Parser class should be used.

The Validator is only checking the *validity* of the claims, such as its expiration time, but it does NOT perform *signature verification* of the token.

func (*Validator) Validate 

func (v *Validator) Validate(claims Claims) error

Validate validates the given claims. It will also perform any custom validation if claims implements the ClaimsValidator interface.

Note: It will NOT perform any *signature verification* on the token that contains the claims and expects that the [Claim] was already successfully verified.

type VerificationKey 

type VerificationKey interface {
	crypto.PublicKey
}

VerificationKey represents a public or secret key for verifying a token's signature.

type VerificationKeySet 

type VerificationKeySet struct {
	Keys []VerificationKey
}

VerificationKeySet is a set of public or secret keys. It is used by the parser to verify a token.

Source Files

View all Source files

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.

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