jwt/token.go

101 lines
3.5 KiB
Go

package jwt
import (
"crypto"
"encoding/base64"
"encoding/json"
)
// 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 Keyfunc func(*Token) (interface{}, error)
// VerificationKey represents a public or secret key for verifying a token's signature.
type VerificationKey interface {
crypto.PublicKey | []uint8
}
// VerificationKeySet is a set of public or secret keys. It is used by the parser to verify a token.
type VerificationKeySet[T VerificationKey] struct {
Keys []T
}
// Token represents a JWT Token. Different fields will be used depending on
// whether you're creating or parsing/verifying a 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
}
// 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.
func New(method SigningMethod, opts ...TokenOption) *Token {
return NewWithClaims(method, MapClaims{}, opts...)
}
// NewWithClaims creates a new [Token] with the specified signing method and
// claims. Additional options can be specified, but are currently unused.
func NewWithClaims(method SigningMethod, claims Claims, opts ...TokenOption) *Token {
return &Token{
Header: map[string]interface{}{
"typ": "JWT",
"alg": method.Alg(),
},
Claims: claims,
Method: method,
}
}
// 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 (t *Token) SignedString(key interface{}) (string, error) {
sstr, err := t.SigningString()
if err != nil {
return "", err
}
sig, err := t.Method.Sign(sstr, key)
if err != nil {
return "", err
}
return sstr + "." + t.EncodeSegment(sig), nil
}
// 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.
func (t *Token) SigningString() (string, error) {
h, err := json.Marshal(t.Header)
if err != nil {
return "", err
}
c, err := json.Marshal(t.Claims)
if err != nil {
return "", err
}
return t.EncodeSegment(h) + "." + t.EncodeSegment(c), nil
}
// 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) EncodeSegment(seg []byte) string {
return base64.RawURLEncoding.EncodeToString(seg)
}