forked from keybase/client
/
token.go
221 lines (195 loc) · 4.75 KB
/
token.go
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// Copyright 2015 Keybase, Inc. All rights reserved. Use of
// this source code is governed by the included BSD license.
//
// Code used to support authentication tokens for arbitrary purposes.
//
package auth
import (
"bytes"
"crypto/rand"
"encoding/hex"
"encoding/json"
"math"
"time"
libkb "github.com/keybase/client/go/libkb"
keybase1 "github.com/keybase/client/go/protocol"
)
const (
TokenType = "auth"
CurrentTokenVersion = 2
ChallengeLengthBytes = 32
ChallengeLengthString = ChallengeLengthBytes * 2 // we use hex encoding
)
type TokenAuth struct {
Server string `json:"server"`
Challenge string `json:"session"`
}
type TokenKey struct {
UID keybase1.UID `json:"uid"`
Username libkb.NormalizedUsername `json:"username"`
KID keybase1.KID `json:"kid"`
}
type TokenBody struct {
Auth TokenAuth `json:"auth"`
Key TokenKey `json:"key"`
Type string `json:"type"`
Version int `json:"version"`
}
type TokenClient struct {
Name string `json:"name"`
Version string `json:"version"`
}
type Token struct {
Body TokenBody `json:"body"`
Client TokenClient `json:"client"`
CreationTime int64 `json:"ctime"`
ExpireIn int `json:"expire_in"`
Tag string `json:"tag"`
}
func NewToken(uid keybase1.UID, username libkb.NormalizedUsername, kid keybase1.KID,
server, challenge string, now int64, expireIn int,
clientName, clientVersion string) *Token {
return &Token{
Body: TokenBody{
Auth: TokenAuth{
Server: server,
Challenge: challenge,
},
Key: TokenKey{
UID: uid,
Username: username,
KID: kid,
},
Type: TokenType,
Version: CurrentTokenVersion,
},
Client: TokenClient{
Name: clientName,
Version: clientVersion,
},
CreationTime: now,
ExpireIn: expireIn,
Tag: "signature",
}
}
func (t Token) Bytes() []byte {
bytes, err := json.Marshal(&t)
if err != nil {
return []byte{}
}
return bytes
}
func (t Token) String() string {
return string(t.Bytes())
}
func VerifyToken(signature, server, challenge string, maxExpireIn int) (*Token, error) {
var t *Token
key, token, _, err := libkb.NaclVerifyAndExtract(signature)
if err != nil {
return nil, err
}
if t, err = parseToken(token); err != nil {
return nil, err
}
if key.GetKID() != t.KID() {
return nil, InvalidTokenKeyError{
expected: key.GetKID().String(),
received: t.KID().String(),
}
}
if TokenType != t.Type() {
return nil, InvalidTokenTypeError{
expected: TokenType,
received: t.Type(),
}
}
if server != t.Server() {
return nil, InvalidTokenServerError{
expected: server,
received: t.Server(),
}
}
if challenge != t.Challenge() {
return nil, InvalidTokenChallengeError{
expected: challenge,
received: t.Challenge(),
}
}
remaining := t.TimeRemaining()
if remaining > maxExpireIn {
return nil, MaxTokenExpiresError{
creationTime: t.CreationTime,
expireIn: t.ExpireIn,
now: time.Now().Unix(),
maxExpireIn: maxExpireIn,
remaining: remaining,
}
}
if remaining <= 0 {
return nil, TokenExpiredError{
creationTime: t.CreationTime,
expireIn: t.ExpireIn,
now: time.Now().Unix(),
}
}
return t, nil
}
func (t Token) TimeRemaining() int {
ctime := time.Unix(t.CreationTime, 0)
expires := ctime.Add(time.Duration(t.ExpireIn) * time.Second)
return int(math.Ceil(expires.Sub(time.Now()).Seconds()))
}
func (t Token) Server() string {
return t.Body.Auth.Server
}
func (t Token) Challenge() string {
return t.Body.Auth.Challenge
}
func (t Token) UID() keybase1.UID {
return t.Body.Key.UID
}
func (t Token) KID() keybase1.KID {
return t.Body.Key.KID
}
func (t Token) Username() libkb.NormalizedUsername {
return t.Body.Key.Username
}
func (t Token) Type() string {
return t.Body.Type
}
func (t Token) Version() int {
return t.Body.Version
}
func (t Token) ClientName() string {
return t.Client.Name
}
func (t Token) ClientVersion() string {
return t.Client.Version
}
func parseToken(token []byte) (*Token, error) {
decoder := json.NewDecoder(bytes.NewReader(token))
decoder.UseNumber()
var t Token
if err := decoder.Decode(&t); err != nil {
return nil, err
}
return &t, nil
}
// GenerateChallenge returns a cryptographically secure random challenge string.
func GenerateChallenge() (string, error) {
buf := make([]byte, ChallengeLengthBytes)
if _, err := rand.Read(buf); err != nil {
return "", err
}
return hex.EncodeToString(buf), nil
}
// IsValidChallenge returns true if the passed challenge is validly formed.
func IsValidChallenge(challenge string) bool {
if len(challenge) != ChallengeLengthString {
return false
}
if _, err := hex.DecodeString(challenge); err != nil {
return false
}
return true
}