func newPrivateKey(size int) (*rsa.PrivateKey, error) {
	privateKey, err := rsa.GenerateKey(rand.Reader, size)
	if err != nil {
		return nil, err
	}
	return privateKey, nil
}
generate a new private key
package crypto
import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/tls"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/pem"
	"fmt"
	"io/ioutil"
	"net"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/klog"
)
const (
	rsaKeySize = 2048
	k8sCAFile  = "/var/run/secrets/kubernetes.io/serviceaccount/ca.crt"
)