code: public String getSigAlgOID() {
          if (algId == null)
              return null;
          ObjectIdentifier oid = algId.getOID();
          return (oid.toString());
      }
docs: Gets the signature algorithm OID string from the certificate.
  For example, the string "1.2.840.10040.4.3"
  
  @return the signature algorithm oid string.