apache poi excel password test

Poitest.java

package jp.ozero.poitest;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

import org.apache.poi.hssf.record.crypto.Biff8EncryptionKey;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRichTextString;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;

public class Poitest {

	public static void main(final String[] args) throws Exception {
		// http://poi.apache.org/encryption.html

		String fname = "c:\\enc.xls";
		FileInputStream input = null;
		BufferedInputStream binput = null;
		POIFSFileSystem poifs = null;
		
		try {
			input = new FileInputStream(fname);
			binput = new BufferedInputStream(input);
			poifs = new POIFSFileSystem(binput);
			
			Biff8EncryptionKey.setCurrentUserPassword("MYPASSWORD");
			
			HSSFWorkbook workbook = new HSSFWorkbook(poifs);
			//
			HSSFSheet sheet = workbook.getSheetAt(0);
			int rows = sheet.getLastRowNum();
			System.out.println("rows:"+rows);

			for (int i = 0; i <= rows; i++) {
				HSSFRow row = sheet.getRow(i);
				if (row == null)
					continue;
				int cols = row.getLastCellNum();
				System.out.println("cols:"+cols);

				for (int j = 0; j <= cols; j++) {
					HSSFCell cell = row.getCell((int) j);
					if (cell == null)
						continue;
					if (cell.getCellType() == HSSFCell.CELL_TYPE_STRING) {
						HSSFRichTextString val = cell.getRichStringCellValue();
						System.out.println(val);
					}
					if (cell.getCellType() == HSSFCell.CELL_TYPE_NUMERIC) {
						double val = cell.getNumericCellValue();
						System.out.println(val);
					}
				}
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				binput.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		System.out.println("done");

	}
}

what encryption key is used for the xssfWorkbook?

Did you mean this line?
https://gist.github.com/ozero/1080046#file-poitest-java-L31
Biff8EncryptionKey.setCurrentUserPassword