identity.go
func (id *Identity) PFX(password string) []byte {
	return toPFX(id.Certificate, id.PrivateKey, password)
}
func (id *Identity) PFX(password string) []byte {
	return toPFX(id.Certificate, id.PrivateKey, password)
}
// PFX wraps the certificate and private key in an encrypted PKCS#12 packet. The
// provided password must be alphanumeric.