@@ -1,14 +1,18 @@

 package api

 import (

+	"encoding/json"

+	"encoding/pem"

 	"fmt"

 	"mime"

+	"os"

 	"path/filepath"

 	"sort"

 	"strconv"

 	"strings"

 	"github.com/Sirupsen/logrus"

+	"github.com/docker/docker/pkg/ioutils"

 	"github.com/docker/docker/pkg/system"

 	"github.com/docker/engine-api/types"

 	"github.com/docker/libtrust"

@@ -135,7 +139,11 @@ func LoadOrCreateTrustKey(trustKeyPath string) (libtrust.PrivateKey, error) {

 		if err != nil {

 			return nil, fmt.Errorf("Error generating key: %s", err)

 		}

-		if err := libtrust.SaveKey(trustKeyPath, trustKey); err != nil {

+		encodedKey, err := serializePrivateKey(trustKey, filepath.Ext(trustKeyPath))

+		if err != nil {

+			return nil, fmt.Errorf("Error serializing key: %s", err)

+		}

+		if err := ioutils.AtomicWriteFile(trustKeyPath, encodedKey, os.FileMode(0600)); err != nil {

 			return nil, fmt.Errorf("Error saving key file: %s", err)

 		}

 	} else if err != nil {

@@ -143,3 +151,19 @@ func LoadOrCreateTrustKey(trustKeyPath string) (libtrust.PrivateKey, error) {

 	}

 	return trustKey, nil

 }

+

+func serializePrivateKey(key libtrust.PrivateKey, ext string) (encoded []byte, err error) {

+	if ext == ".json" || ext == ".jwk" {

+		encoded, err = json.Marshal(key)

+		if err != nil {

+			return nil, fmt.Errorf("unable to encode private key JWK: %s", err)

+		}

+	} else {

+		pemBlock, err := key.PEMBlock()

+		if err != nil {

+			return nil, fmt.Errorf("unable to encode private key PEM: %s", err)

+		}

+		encoded = pem.EncodeToMemory(pemBlock)

+	}

+	return

+}