func (g giImpl) PublicCertificates() ([]info.Certificate, error) {
certs, err := appengine.PublicCertificates(g.aeCtx)
if err != nil {
return nil, err
}
ret := make([]info.Certificate, len(certs))
for i, c := range certs {
ret[i] = info.Certificate(c)
}
return ret, nil
}
// Certificate will return all public certificates assigned by App Engine in PEM format.
func Certificate(ctx context.Context, w http.ResponseWriter, r *http.Request) (status int, err error) {
var certs []appengine.Certificate
if certs, err = appengine.PublicCertificates(ctx); err != nil {
return http.StatusInternalServerError, err
}
w.Header().Add("Content-Type", "application/x-pem-file")
for _, cert := range certs {
w.Write([]byte("KeyName: \"" + cert.KeyName + "\""))
w.Write(cert.Data)
}
return http.StatusOK, nil
}
// PublicCerts returns list of public certificates.
func PublicCerts(c context.Context) (*PublicCertificates, error) {
aeCerts, err := appengine.PublicCertificates(c)
if err != nil {
return nil, err
}
var certs []Certificate
for _, ac := range aeCerts {
certs = append(certs, Certificate{
KeyName: ac.KeyName,
X509CertificatePEM: string(ac.Data),
})
}
return &PublicCertificates{
Certificates: certs,
Timestamp: time.Now().Unix(),
}, nil
}
// Certificate will return all public certificates assigned by App Engine in PEM format.
func Certificate(ctx context.Context, w http.ResponseWriter, r *http.Request) (int, error) {
certs, err := appengine.PublicCertificates(ctx)
if err != nil {
return http.StatusInternalServerError, err
}
// TODO(flowlo): Is this really the appropriate MIME type?
w.Header().Add("Content-Type", "application/x-pem-file")
for _, cert := range certs {
p := make([]byte, 13+len(cert.KeyName)+len(cert.Data))
p = append(p, []byte("KeyName: \""+cert.KeyName+"\"\n")...)
p = append(p, cert.Data...)
p = append(p, []byte("\n")...)
if _, err := w.Write(p); err != nil {
return http.StatusInternalServerError, err
}
}
return http.StatusOK, nil
}
// VerifyBytes verifies a signature produced by appengine.SignBytes. c must be a
// context.Context created from appengine.NewContext.
func VerifyBytes(c context.Context, bytes []byte, sig []byte) error {
certs, err := appengine.PublicCertificates(c)
if err != nil {
return err
}
lastErr := ErrNoPublicCertificates
signBytesHash := crypto.SHA256
h := signBytesHash.New()
h.Write(bytes)
hashed := h.Sum(nil)
for _, cert := range certs {
block, _ := pem.Decode(cert.Data)
if block == nil {
lastErr = ErrPemDecodeFailure
continue
}
x509Cert, err := x509.ParseCertificate(block.Bytes)
if err != nil {
lastErr = err
continue
}
pubkey, ok := x509Cert.PublicKey.(*rsa.PublicKey)
if !ok {
lastErr = ErrNotRSAPublicKey
continue
}
err = rsa.VerifyPKCS1v15(pubkey, signBytesHash, hashed, sig)
if err != nil {
lastErr = err
continue
}
return nil
}
return lastErr
}
// Implements the Verify method from SigningMethod
// For this signing method, a valid appengine.Context must be
// passed as the key.
func (s *SigningMethodAppEngine) Verify(signingString, signature string, key interface{}) error {
var ctx context.Context
switch k := key.(type) {
case context.Context:
ctx = k
default:
return jwt.ErrInvalidKey
}
var sig []byte
var err error
if sig, err = jwt.DecodeSegment(signature); err != nil {
return err
}
var certs certificates
certs, err = appengine.PublicCertificates(ctx)
if err != nil {
return err
}
hasher := sha256.New()
hasher.Write([]byte(signingString))
var certErr error
for _, cert := range certs {
rsaKey, err := jwt.ParseRSAPublicKeyFromPEM(cert.Data)
if err != nil {
return err
}
if certErr = rsa.VerifyPKCS1v15(rsaKey, crypto.SHA256, hasher.Sum(nil), sig); certErr == nil {
return nil
}
}
return certErr
}