/*****************************************************************/
/* Copyright 2013 Code Strategies                                */
/* This code may be freely used and distributed in any project.  */
/* However, please do not remove this credit if you publish this */
/* code in paper or electronic form, such as on a web site.      */
/*****************************************************************/

package test;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Date;

import org.apache.commons.codec.binary.Hex;

public class MessageDigestTest {

	public static void main(String[] args) {

		try {
			String file = "httpd-2.2.6-win32-src-r2.zip";
			MessageDigest md = MessageDigest.getInstance("MD5");

			getDigestViaByteArray(new FileInputStream(file), md, 128);
			getDigestViaByteArray(new FileInputStream(file), md, 256);
			getDigestViaByteArray(new FileInputStream(file), md, 512);
			getDigestViaByteArray(new FileInputStream(file), md, 1024);
			getDigestViaByteArray(new FileInputStream(file), md, 2048);
			getDigestViaByteArray(new FileInputStream(file), md, 4096);
			getDigestViaByteArray(new FileInputStream(file), md, 8192);

			getDigestViaOneByteAtATime(new FileInputStream(file), md);

		} catch (Throwable e) {
			e.printStackTrace();
		}

	}

	public static String getDigestViaByteArray(InputStream is, MessageDigest md, int arraySize)
			throws NoSuchAlgorithmException, IOException {
		Date t1 = new Date();

		md.reset();
		byte[] bytes = new byte[arraySize];
		int numBytes;
		while ((numBytes = is.read(bytes)) != -1) {
			md.update(bytes, 0, numBytes);
		}
		byte[] digest = md.digest();
		String result = new String(Hex.encodeHex(digest));
		
		Date t2 = new Date();

		System.out.println("MD5 Digest:" + result);
		System.out.print("Using byte array (size " + arraySize + "): ");
		System.out.println((t2.getTime() - t1.getTime()) + " milliseconds\n");

		return result;
	}

	public static String getDigestViaOneByteAtATime(InputStream is, MessageDigest md) throws NoSuchAlgorithmException,
			IOException {
		Date t1 = new Date();

		md.reset();
		int oneByte;
		while ((oneByte = is.read()) != -1) {
			md.update((byte) oneByte);
		}

		byte[] digest = md.digest();
		String result = new String(Hex.encodeHex(digest));

		Date t2 = new Date();

		System.out.println("MD5 Digest:" + result);
		System.out.print("One byte at a time: ");
		System.out.println((t2.getTime() - t1.getTime()) + " milliseconds\n");

		return result;
	}

}