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// Copyright 2017 The LUCI 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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package openid
import (
// IDToken is verified deserialized ID token.
// See
type IDToken struct {
Iss string `json:"iss"`
AtHash string `json:"at_hash"`
EmailVerified bool `json:"email_verified"`
Sub string `json:"sub"`
Azp string `json:"azp"`
Email string `json:"email"`
Profile string `json:"profile"`
Picture string `json:"picture"`
Name string `json:"name"`
Aud string `json:"aud"`
Iat int64 `json:"iat"`
Exp int64 `json:"exp"`
Nonce string `json:"nonce"`
Hd string `json:"hd"`
const allowedClockSkew = 30 * time.Second
// VerifyIDToken deserializes and verifies the ID token.
// It checks the signature, expiration time and verifies fields `iss` and
// `email_verified`.
// It checks `aud` and `sub` are present, but does NOT verify them any further.
// It is the caller's responsibility to do so.
// This is a fast local operation.
func VerifyIDToken(ctx context.Context, token string, keys *JSONWebKeySet, issuer string) (*IDToken, error) {
// See
body, err := keys.VerifyJWT(token)
if err != nil {
return nil, err
tok := &IDToken{}
if err := json.Unmarshal(body, tok); err != nil {
return nil, errors.Annotate(err, "bad ID token - not JSON").Err()
exp := time.Unix(tok.Exp, 0)
now := clock.Now(ctx)
switch {
case tok.Iss != issuer && "https://"+tok.Iss != issuer:
return nil, errors.Reason("bad ID token - expecting issuer %q, got %q", issuer, tok.Iss).Err()
case exp.Add(allowedClockSkew).Before(now):
return nil, errors.Reason("bad ID token - expired %s ago", now.Sub(exp)).Err()
case !tok.EmailVerified:
return nil, errors.Reason("bad ID token - the email %q is not verified", tok.Email).Err()
case tok.Aud == "":
return nil, errors.Reason("bad ID token - the audience is missing").Err()
case tok.Sub == "":
return nil, errors.Reason("bad ID token - the subject is missing").Err()
return tok, nil