diff --git a/pkg/kubeapiserver/authenticator/config.go b/pkg/kubeapiserver/authenticator/config.go
index 780d4f4e7be..9b1655b139a 100644
--- a/pkg/kubeapiserver/authenticator/config.go
+++ b/pkg/kubeapiserver/authenticator/config.go
@@ -49,7 +49,6 @@ import (
 
 	// Initialize all known client auth plugins.
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
-	"k8s.io/client-go/util/keyutil"
 	"k8s.io/kubernetes/pkg/serviceaccount"
 )
 
@@ -325,12 +324,6 @@ func (c *authenticationConfigUpdater) updateAuthenticationConfig(ctx context.Con
 	return nil
 }
 
-// IsValidServiceAccountKeyFile returns true if a valid public RSA key can be read from the given file
-func IsValidServiceAccountKeyFile(file string) bool {
-	_, err := keyutil.PublicKeysFromFile(file)
-	return err == nil
-}
-
 // newAuthenticatorFromTokenFile returns an authenticator.Token or an error
 func newAuthenticatorFromTokenFile(tokenAuthFile string) (authenticator.Token, error) {
 	tokenAuthenticator, err := tokenfile.NewCSV(tokenAuthFile)