code: public void setChecksum(ChecksumAlgorithm algorithm,
                              String value)
          throws IOException, ServerException {
          String arguments = algorithm.toFtpCmdArgument() + " " + value;
  
          Command cmd = new Command("SCKS", arguments);
          try {
              controlChannel.execute(cmd);
          } catch (UnexpectedReplyCodeException urce) {
              throw ServerException.embedUnexpectedReplyCodeException(urce);
          } catch (FTPReplyParseException rpe) {
              throw ServerException.embedFTPReplyParseException(rpe);
          }
      }
docs: Sets the checksum values ahead of the transfer
  @param algorithm the checksume algorithm
  @param value the checksum value as hexadecimal number
  @exception ServerException if an error occured.