Improve private and public key configuration

internal/fs/fs.go

@@ -138,22 +138,40 @@ func CopyDirectory(src, dest string) error {
 	)
 }
 
-func ReadKey(key string) ([]byte, error) {
+// ReadKey returns either the content of the file specified at path, if it exists,
+// or []byte(key) otherwise. It is an error to specify both or none arguments, or
+// specify an empty or unreadable file. If there is no error then the return []byte is non-empty.
+func ReadKey(key, path string) ([]byte, error) {
+	if (key != "" && path != "") || (key == "" && path == "") {
+		return nil, errors.New("provide either key or path to key")
+	}
+
 	var bts []byte
-	if stat, err := os.Stat(key); err == nil {
+
+	if path == "" {
+		bts = []byte(key)
+	} else {
+		stat, err := os.Stat(path)
+		if err != nil {
+			return nil, errors.New("no key found at specified path")
+		}
 		if stat.IsDir() {
 			return nil, errors.New("cannot read key from a directory")
 		}
-		bts, err = ioutil.ReadFile(key)
+		bts, err = ioutil.ReadFile(path)
 		if err != nil {
 			return nil, err
 		}
-	} else {
-		bts = []byte(key)
+	}
+
+	if len(bts) == 0 {
+		return nil, errors.New("empty key provided")
 	}
 	return bts, nil
 }
 
+// Base64Decode decodes the specified bytes as any of the Base64 dialects:
+// standard encoding (+, /) and URL encoding (-, _), with or without padding.
 func Base64Decode(b []byte) ([]byte, error) {
 	var (
 		err       error

irma/cmd/session.go

@@ -162,8 +162,9 @@ func postRequest(serverurl string, request irma.RequestorRequest, name, authmeth
 			jwtstr string
 			bts    []byte
 		)
-		if bts, err = fs.ReadKey(key); err != nil {
-			return nil, nil, err
+		// If the key refers to an existing file, use contents of the file as key
+		if bts, err = fs.ReadKey("", key); err != nil {
+			bts = []byte(key)
 		}
 		if authmethod == "hmac" {
 			jwtalg = jwt.SigningMethodHS256

server/irmaserver/auth.go

@@ -77,14 +77,9 @@ func (hauth *HmacAuthenticator) Authenticate(
 }
 
 func (hauth *HmacAuthenticator) Initialize(name string, requestor Requestor) error {
-	if requestor.AuthenticationKey == "" {
-		return errors.Errorf("Requestor %s has no authentication key", name)
-	}
-
-	// Read file contents or string contents
-	bts, err := fs.ReadKey(requestor.AuthenticationKey)
+	bts, err := fs.ReadKey(requestor.AuthenticationKey, requestor.AuthenticationKeyFile)
 	if err != nil {
-		return err
+		return errors.WrapPrefix(err, "Failed to read key of requestor "+name, 0)
 	}
 
 	// We accept any of the base64 encodings
@@ -105,13 +100,11 @@ func (pkauth *PublicKeyAuthenticator) Authenticate(
 }
 
 func (pkauth *PublicKeyAuthenticator) Initialize(name string, requestor Requestor) error {
-	bts, err := fs.ReadKey(requestor.AuthenticationKey)
+	bts, err := fs.ReadKey(requestor.AuthenticationKey, requestor.AuthenticationKeyFile)
 	if err != nil {
-		return err
-	}
-	if len(bts) == 0 {
-		return errors.Errorf("Requestor %s has invalid public key", name)
+		return errors.WrapPrefix(err, "Failed to read key of requestor "+name, 0)
 	}
+
 	pk, err := jwt.ParseRSAPublicKeyFromPEM(bts)
 	if err != nil {
 		return err
@@ -140,12 +133,9 @@ func (pskauth *PresharedKeyAuthenticator) Authenticate(
 }
 
 func (pskauth *PresharedKeyAuthenticator) Initialize(name string, requestor Requestor) error {
-	if requestor.AuthenticationKey == "" {
-		return errors.Errorf("Requestor %s has no authentication key", name)
-	}
-	bts, err := fs.ReadKey(requestor.AuthenticationKey)
+	bts, err := fs.ReadKey(requestor.AuthenticationKey, requestor.AuthenticationKeyFile)
 	if err != nil {
-		return err
+		return errors.WrapPrefix(err, "Failed to read key of requestor "+name, 0)
 	}
 	pskauth.presharedkeys[string(bts)] = name
 	return nil

server/irmaserver/conf.go

@@ -3,7 +3,6 @@ package irmaserver
 import (
 	"crypto/rsa"
 	"fmt"
-	"io/ioutil"
 	"regexp"
 	"strconv"
 	"strings"
@@ -46,6 +45,7 @@ type Configuration struct {
 
 	// Private key to sign result JWTs with. If absent, /result-jwt and /getproof are disabled.
 	JwtPrivateKey     string `json:"jwtprivatekey" mapstructure:"jwtprivatekey"`
+	JwtPrivateKeyFile string `json:"jwtprivatekeyfile" mapstructure:"jwtprivatekeyfile"`
 
 	// Max age in seconds of a session request JWT (using iat field)
 	MaxRequestAge int `json:"maxrequestage" mapstructure:"maxrequestage"`
@@ -70,6 +70,7 @@ type Requestor struct {
 
 	AuthenticationMethod  AuthenticationMethod `json:"authmethod" mapstructure:"authmethod"`
 	AuthenticationKey     string               `json:"key" mapstructure:"key"`
+	AuthenticationKeyFile string               `json:"keyfile" mapstructure:"keyfile"`
 }
 
 // CanIssue returns whether or not the specified requestor may issue the specified credentials.
@@ -262,21 +263,13 @@ func (conf *Configuration) validatePermissionSet(requestor string, requestorperm
 }
 
 func (conf *Configuration) readPrivateKey() error {
-	if conf.JwtPrivateKey == "" {
+	if conf.JwtPrivateKey == "" && conf.JwtPrivateKeyFile == "" {
 		return nil
 	}
 
-	var keybytes []byte
-	var err error
-	if strings.HasPrefix(conf.JwtPrivateKey, "-----BEGIN") {
-		keybytes = []byte(conf.JwtPrivateKey)
-	} else {
-		if err = fs.AssertPathExists(conf.JwtPrivateKey); err != nil {
-			return err
-		}
-		if keybytes, err = ioutil.ReadFile(conf.JwtPrivateKey); err != nil {
-			return err
-		}
+	keybytes, err := fs.ReadKey(conf.JwtPrivateKey, conf.JwtPrivateKeyFile)
+	if err != nil {
+		return errors.WrapPrefix(err, "failed to read private key", 0)
 	}
 
 	conf.jwtPrivateKey, err = jwt.ParseRSAPrivateKeyFromPEM(keybytes)

server/irmaserver/irmad/main.go

@@ -75,7 +75,8 @@ func setFlags(cmd *cobra.Command) error {
 	flags.String("cachepath", cachepath, "Directory for writing cache files to")
 	flags.Uint("schemeupdate", 60, "Update IRMA schemes every x minutes (0 to disable)")
 	flags.StringP("jwtissuer", "j", "irmaserver", "JWT issuer")
-	flags.StringP("jwtprivatekey", "w", "", "JWT private key or path to it")
+	flags.String("jwtprivatekey", "", "JWT private key")
+	flags.String("jwtprivatekeyfile", "", "Path to JWT private key")
 	flags.Int("maxrequestage", 300, "Max age in seconds of a session request JWT")
 	flags.StringP("url", "u", defaulturl, "External URL to server to which the IRMA client connects")
 	flags.StringP("listenaddr", "l", "0.0.0.0", "Address at which to listen")
@@ -151,6 +152,7 @@ func configure() error {
 		GlobalPermissions:              irmaserver.Permissions{},
 		JwtIssuer:                      viper.GetString("jwtissuer"),
 		JwtPrivateKey:                  viper.GetString("jwtprivatekey"),
+		JwtPrivateKeyFile:              viper.GetString("jwtprivatekeyfile"),
 		MaxRequestAge:                  viper.GetInt("maxrequestage"),
 		Verbose:                        viper.GetInt("verbose"),
 		Quiet:                          viper.GetBool("quiet"),