forked from nats-io/jwt
/
claims.go
305 lines (268 loc) · 7.37 KB
/
claims.go
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/*
* Copyright 2018-2019 The NATS Authors
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jwt
import (
"crypto/sha512"
"encoding/base32"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"strings"
"time"
"github.com/itsabgr/nats-nkeys"
)
// ClaimType is used to indicate the type of JWT being stored in a Claim
type ClaimType string
const (
// AccountClaim is the type of an Account JWT
AccountClaim = "account"
//ActivationClaim is the type of an activation JWT
ActivationClaim = "activation"
//UserClaim is the type of an user JWT
UserClaim = "user"
//OperatorClaim is the type of an operator JWT
OperatorClaim = "operator"
//ServerClaim is the type of an server JWT
// Deprecated: ServerClaim is not supported
ServerClaim = "server"
// ClusterClaim is the type of an cluster JWT
// Deprecated: ClusterClaim is not supported
ClusterClaim = "cluster"
)
// Claims is a JWT claims
type Claims interface {
Claims() *ClaimsData
Encode(kp nkeys.KeyPair) (string, error)
ExpectedPrefixes() []nkeys.PrefixByte
Payload() interface{}
String() string
Validate(vr *ValidationResults)
Verify(payload string, sig []byte) bool
}
// ClaimsData is the base struct for all claims
type ClaimsData struct {
Audience string `json:"aud,omitempty"`
Expires int64 `json:"exp,omitempty"`
ID string `json:"jti,omitempty"`
IssuedAt int64 `json:"iat,omitempty"`
Issuer string `json:"iss,omitempty"`
Name string `json:"name,omitempty"`
NotBefore int64 `json:"nbf,omitempty"`
Subject string `json:"sub,omitempty"`
Tags TagList `json:"tags,omitempty"`
Type ClaimType `json:"type,omitempty"`
}
// Prefix holds the prefix byte for an NKey
type Prefix struct {
nkeys.PrefixByte
}
func encodeToString(d []byte) string {
return base64.RawURLEncoding.EncodeToString(d)
}
func decodeString(s string) ([]byte, error) {
return base64.RawURLEncoding.DecodeString(s)
}
func serialize(v interface{}) (string, error) {
j, err := json.Marshal(v)
if err != nil {
return "", err
}
return encodeToString(j), nil
}
func (c *ClaimsData) doEncode(header *Header, kp nkeys.KeyPair, claim Claims) (string, error) {
if header == nil {
return "", errors.New("header is required")
}
if kp == nil {
return "", errors.New("keypair is required")
}
if c.Subject == "" {
return "", errors.New("subject is not set")
}
h, err := serialize(header)
if err != nil {
return "", err
}
issuerBytes, err := kp.PublicKey()
if err != nil {
return "", err
}
prefixes := claim.ExpectedPrefixes()
if prefixes != nil {
ok := false
for _, p := range prefixes {
switch p {
case nkeys.PrefixByteAccount:
if nkeys.IsValidPublicAccountKey(issuerBytes) {
ok = true
}
case nkeys.PrefixByteOperator:
if nkeys.IsValidPublicOperatorKey(issuerBytes) {
ok = true
}
case nkeys.PrefixByteServer:
if nkeys.IsValidPublicServerKey(issuerBytes) {
ok = true
}
case nkeys.PrefixByteCluster:
if nkeys.IsValidPublicClusterKey(issuerBytes) {
ok = true
}
case nkeys.PrefixByteUser:
if nkeys.IsValidPublicUserKey(issuerBytes) {
ok = true
}
}
}
if !ok {
return "", fmt.Errorf("unable to validate expected prefixes - %v", prefixes)
}
}
c.Issuer = string(issuerBytes)
c.IssuedAt = time.Now().UTC().Unix()
c.ID, err = c.hash()
if err != nil {
return "", err
}
payload, err := serialize(claim)
if err != nil {
return "", err
}
sig, err := kp.Sign([]byte(payload))
if err != nil {
return "", err
}
eSig := encodeToString(sig)
return fmt.Sprintf("%s.%s.%s", h, payload, eSig), nil
}
func (c *ClaimsData) hash() (string, error) {
j, err := json.Marshal(c)
if err != nil {
return "", err
}
h := sha512.New512_256()
h.Write(j)
return base32.StdEncoding.WithPadding(base32.NoPadding).EncodeToString(h.Sum(nil)), nil
}
// Encode encodes a claim into a JWT token. The claim is signed with the
// provided nkey's private key
func (c *ClaimsData) Encode(kp nkeys.KeyPair, payload Claims) (string, error) {
return c.doEncode(&Header{TokenTypeJwt, AlgorithmNkey}, kp, payload)
}
// Returns a JSON representation of the claim
func (c *ClaimsData) String(claim interface{}) string {
j, err := json.MarshalIndent(claim, "", " ")
if err != nil {
return ""
}
return string(j)
}
func parseClaims(s string, target Claims) error {
h, err := decodeString(s)
if err != nil {
return err
}
return json.Unmarshal(h, &target)
}
// Verify verifies that the encoded payload was signed by the
// provided public key. Verify is called automatically with
// the claims portion of the token and the public key in the claim.
// Client code need to insure that the public key in the
// claim is trusted.
func (c *ClaimsData) Verify(payload string, sig []byte) bool {
// decode the public key
kp, err := nkeys.FromPublicKey(c.Issuer)
if err != nil {
return false
}
if err := kp.Verify([]byte(payload), sig); err != nil {
return false
}
return true
}
// Validate checks a claim to make sure it is valid. Validity checks
// include expiration and not before constraints.
func (c *ClaimsData) Validate(vr *ValidationResults) {
now := time.Now().UTC().Unix()
if c.Expires > 0 && now > c.Expires {
vr.AddTimeCheck("claim is expired")
}
if c.NotBefore > 0 && c.NotBefore > now {
vr.AddTimeCheck("claim is not yet valid")
}
}
// IsSelfSigned returns true if the claims issuer is the subject
func (c *ClaimsData) IsSelfSigned() bool {
return c.Issuer == c.Subject
}
// Decode takes a JWT string decodes it and validates it
// and return the embedded Claims. If the token header
// doesn't match the expected algorithm, or the claim is
// not valid or verification fails an error is returned.
func Decode(token string, target Claims) error {
// must have 3 chunks
chunks := strings.Split(token, ".")
if len(chunks) != 3 {
return errors.New("expected 3 chunks")
}
_, err := parseHeaders(chunks[0])
if err != nil {
return err
}
if err := parseClaims(chunks[1], target); err != nil {
return err
}
sig, err := decodeString(chunks[2])
if err != nil {
return err
}
if !target.Verify(chunks[1], sig) {
return errors.New("claim failed signature verification")
}
prefixes := target.ExpectedPrefixes()
if prefixes != nil {
ok := false
issuer := target.Claims().Issuer
for _, p := range prefixes {
switch p {
case nkeys.PrefixByteAccount:
if nkeys.IsValidPublicAccountKey(issuer) {
ok = true
}
case nkeys.PrefixByteOperator:
if nkeys.IsValidPublicOperatorKey(issuer) {
ok = true
}
case nkeys.PrefixByteServer:
if nkeys.IsValidPublicServerKey(issuer) {
ok = true
}
case nkeys.PrefixByteCluster:
if nkeys.IsValidPublicClusterKey(issuer) {
ok = true
}
case nkeys.PrefixByteUser:
if nkeys.IsValidPublicUserKey(issuer) {
ok = true
}
}
}
if !ok {
return fmt.Errorf("unable to validate expected prefixes - %v", prefixes)
}
}
return nil
}