/*
* RED5 Open Source Flash Server - http://code.google.com/p/red5/
*
* Copyright 2006-2012 by respective authors (see below). All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.red5.io.utils;
/*
* RandomGUID
* @version 1.2.1 11/05/02
* @author Marc A. Mnich
*
* From www.JavaExchange.com, Open Software licensing
*
* 11/05/02 -- Performance enhancement from Mike Dubman.
* Moved InetAddr.getLocal to static block. Mike has measured
* a 10 fold improvement in run time.
* 01/29/02 -- Bug fix: Improper seeding of nonsecure Random object
* caused duplicate GUIDs to be produced. Random object
* is now only created once per JVM.
* 01/19/02 -- Modified random seeding and added new constructor
* to allow secure random feature.
* 01/14/02 -- Added random function seeding with JVM run time
*
*/
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Random;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/*
* In the multitude of java GUID generators, I found none that
* guaranteed randomness. GUIDs are guaranteed to be globally unique
* by using ethernet MACs, IP addresses, time elements, and sequential
* numbers. GUIDs are not expected to be random and most often are
* easy/possible to guess given a sample from a given generator.
* SQL Server, for example generates GUID that are unique but
* sequential within a given instance.
*
* GUIDs can be used as security devices to hide things such as
* files within a filesystem where listings are unavailable (e.g. files
* that are served up from a Web server with indexing turned off).
* This may be desirable in cases where standard authentication is not
* appropriate. In this scenario, the RandomGUIDs are used as directories.
* Another example is the use of GUIDs for primary keys in a database
* where you want to ensure that the keys are secret. Random GUIDs can
* then be used in a URL to prevent hackers (or users) from accessing
* records by guessing or simply by incrementing sequential numbers.
*
* There are many other possibilities of using GUIDs in the realm of
* security and encryption where the element of randomness is important.
* This class was written for these purposes but can also be used as a
* general purpose GUID generator as well.
*
* RandomGUID generates truly random GUIDs by using the system's
* IP address (name/IP), system time in milliseconds (as an integer),
* and a very large random number joined together in a single String
* that is passed through an MD5 hash. The IP address and system time
* make the MD5 seed globally unique and the random number guarantees
* that the generated GUIDs will have no discernible pattern and
* cannot be guessed given any number of previously generated GUIDs.
* It is generally not possible to access the seed information (IP, time,
* random number) from the resulting GUIDs as the MD5 hash algorithm
* provides one way encryption.
*
* ----> Security of RandomGUID: <-----
* RandomGUID can be called one of two ways -- with the basic java Random
* number generator or a cryptographically strong random generator
* (SecureRandom). The choice is offered because the secure random
* generator takes about 3.5 times longer to generate its random numbers
* and this performance hit may not be worth the added security
* especially considering the basic generator is seeded with a
* cryptographically strong random seed.
*
* Seeding the basic generator in this way effectively decouples
* the random numbers from the time component making it virtually impossible
* to predict the random number component even if one had absolute knowledge
* of the System time. Thanks to Ashutosh Narhari for the suggestion
* of using the static method to prime the basic random generator.
*
* Using the secure random option, this class complies with the statistical
* random number generator tests specified in FIPS 140-2, Security
* Requirements for Cryptographic Modules, section 4.9.1.
*
* I converted all the pieces of the seed to a String before handing
* it over to the MD5 hash so that you could print it out to make
* sure it contains the data you expect to see and to give a nice
* warm fuzzy. If you need better performance, you may want to stick
* to byte[] arrays.
*
* I believe that it is important that the algorithm for
* generating random GUIDs be open for inspection and modification.
* This class is free for all uses.
*
*
* - Marc
*/
public class RandomGUID extends Object {
private static Logger log = LoggerFactory.getLogger(RandomGUID.class);
private static final String hexChars = "0123456789ABCDEF";
private static Random myRand;
private static SecureRandom mySecureRand;
private static String s_id;
public String valueBeforeMD5 = "";
public String valueAfterMD5 = "";
/*
* Static block to take care of one time secureRandom seed.
* It takes a few seconds to initialize SecureRandom. You might
* want to consider removing this static block or replacing
* it with a "time since first loaded" seed to reduce this time.
* This block will run only once per JVM instance.
*/
static {
mySecureRand = new SecureRandom();
long secureInitializer = mySecureRand.nextLong();
myRand = new Random(secureInitializer);
try {
s_id = InetAddress.getLocalHost().toString();
} catch (UnknownHostException e) {
log.warn("Exception {}", e);
}
}
/*
* Default constructor. With no specification of security option,
* this constructor defaults to lower security, high performance.
*/
public RandomGUID() {
getRandomGUID(false);
}
/*
* Constructor with security option. Setting secure true
* enables each random number generated to be cryptographically
* strong. Secure false defaults to the standard Random function seeded
* with a single cryptographically strong random number.
*/
public RandomGUID(boolean secure) {
getRandomGUID(secure);
}
/*
* Method to generate the random GUID
*/
private void getRandomGUID(boolean secure) {
MessageDigest md5 = null;
StringBuilder sbValueBeforeMD5 = new StringBuilder();
try {
md5 = MessageDigest.getInstance("MD5");
long time = System.currentTimeMillis();
long rand = 0;
if (secure) {
rand = mySecureRand.nextLong();
} else {
rand = myRand.nextLong();
}
// This StringBuffer can be a long as you need; the MD5
// hash will always return 128 bits. You can change
// the seed to include anything you want here.
// You could even stream a file through the MD5 making
// the odds of guessing it at least as great as that
// of guessing the contents of the file!
sbValueBeforeMD5.append(s_id);
sbValueBeforeMD5.append(':');
sbValueBeforeMD5.append(Long.toString(time));
sbValueBeforeMD5.append(':');
sbValueBeforeMD5.append(Long.toString(rand));
valueBeforeMD5 = sbValueBeforeMD5.toString();
md5.update(valueBeforeMD5.getBytes());
byte[] array = md5.digest();
StringBuilder sb = new StringBuilder();
for (int j = 0; j < array.length; ++j) {
int b = array[j] & 0xFF;
if (b < 0x10)
sb.append('0');
sb.append(Integer.toHexString(b));
}
valueAfterMD5 = sb.toString();
} catch (NoSuchAlgorithmException e) {
System.out.println("Error: " + e);
} catch (Exception e) {
System.out.println("Error:" + e);
}
}
/**
* Returns a byte array for the given uuid or guid.
*
* @param uid
* @return array of bytes containing the id
*/
public final static byte[] toByteArray(String uid) {
byte[] result = new byte[16];
char[] chars = uid.toCharArray();
int r = 0;
for (int i = 0; i < chars.length; ++i) {
if (chars[i] == '-') {
continue;
}
int h1 = Character.digit(chars[i], 16);
++i;
int h2 = Character.digit(chars[i], 16);
result[(r++)] = (byte) ((h1 << 4 | h2) & 0xFF);
}
return result;
}
/**
* Returns a uuid / guid for a given byte array.
*
* @param ba array of bytes containing the id
* @return id
*/
public static String fromByteArray(byte[] ba) {
if ((ba != null) && (ba.length == 16)) {
StringBuilder result = new StringBuilder(36);
for (int i = 0; i < 16; ++i) {
if ((i == 4) || (i == 6) || (i == 8) || (i == 10)) {
result.append('-');
}
result.append(hexChars.charAt(((ba[i] & 0xF0) >>> 4)));
result.append(hexChars.charAt((ba[i] & 0xF)));
}
return result.toString();
}
return null;
}
/**
* Returns a nice neat formatted string.
*
* @param str unformatted string
* @return formatted string
*/
public static String getPrettyFormatted(String str) {
return String.format("%s-%s-%s-%s-%s", new Object[] { str.substring(0, 8), str.substring(8, 12),
str.substring(12, 16), str.substring(16, 20), str.substring(20) });
}
/*
* Convert to the standard format for GUID
* (Useful for SQL Server UniqueIdentifiers, etc.)
* Example: C2FEEEAC-CFCD-11D1-8B05-00600806D9B6
*/
public String toString() {
return RandomGUID.getPrettyFormatted(valueAfterMD5.toUpperCase());
}
/*
* Demonstraton and self test of class
*/
public static void main(String args[]) {
for (int i = 0; i < 100; i++) {
RandomGUID myGUID = new RandomGUID();
System.out.println("Seeding String=" + myGUID.valueBeforeMD5);
System.out.println("rawGUID=" + myGUID.valueAfterMD5);
System.out.println("RandomGUID=" + myGUID.toString());
}
}
}