code: func validateCSR(obj *certificates.CertificateSigningRequest) error {
  	csr, err := certificates.ParseCSR(obj)
  	if err != nil {
  		return err
  	}
  	// check that the signature is valid
  	err = csr.CheckSignature()
  	if err != nil {
  		return err
  	}
  	return nil
  }
docs: // validateCSR validates the signature and formatting of a base64-wrapped,
  // PEM-encoded PKCS#10 certificate signing request. If this is invalid, we must
  // not accept the CSR for further processing.