Imports k8s.io/client-go/util/cert k8s.io/apiserver/pkg/authentication/user github.com/golang/glog k8s.io/apimachinery/pkg/util/sets Standard library imports crypto/x509/pkix crypto/rsa encoding/pem crypto crypto/ecdsa sync bytes crypto/rand crypto/tls crypto/x509 errors fmt io time io/ioutil math/big math/rand net os path/filepath sort strconv