Mega Code Archive
Generates a secure random word with the given length consisting of uppercase and lowercase letters and numbers
<![CDATA[
//package org.boticelli.util;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Arrays;
//import org.apache.log4j.Logger;
public class RandomUtil
{
// protected static Logger log = Logger.getLogger(RandomUtil.class);
private static String[] secureRndNames = new String[] {
System.getProperty("boticelli.securerandom"), "SHA1PRNG", "IBMSecureRandom" };
private RandomUtil()
{
}
/**
* Creates a new secure random number generator. The following secure random
* algorithm names are tried:
* <ul>
* <li>The value of system property "boticelli.securerandom", if set. </li>
* <li> "SHA1PRNG" </li>
* <li> "IBMSecureRandom" (available if running in the IBM JRE) </li>
* </ul>
*/
private static SecureRandom createSecureRandom()
{
SecureRandom secureRnd = null;
try
{
for (int i = 0; i < secureRndNames.length; i++)
{
try
{
if (secureRndNames[i] != null)
{
secureRnd = SecureRandom.getInstance(secureRndNames[i]);
break;
}
}
catch (NoSuchAlgorithmException nsae)
{
// log.debug("no secure random algorithm named \"" + secureRndNames[i] + "\"",
// nsae);
}
}
if (secureRnd == null)
{
throw new IllegalStateException("no secure random algorithm found. (tried " +
Arrays.asList(secureRndNames) + ")");
}
secureRnd.setSeed(System.currentTimeMillis());
}
catch (Exception e)
{
// log.fatal("error initializing secure random", e);
}
return secureRnd;
}
/**
* Generates a secure random word with the given length consisting of
* uppercase and lowercase letters and numbers.
*
* @param len Amount of random characters to generate
* @return random Word containing letters and numbers.
*/
public static String createWord(int len)
{
return createWord(len, null);
}
/**
* Generates a secure random word with the given length.
*
* @param len Amount of random characters to generate
* @param alphabet Alphabet to generate from.
* @return random Word containing letters and numbers.
*/
public static String createWord(int len, char[] alphabet)
{
SecureRandom random = createSecureRandom();
if (alphabet == null)
{
alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890"
.toCharArray();
}
StringBuffer out = new StringBuffer(len);
for (int i = 0; i < len; i++)
{
out.append(alphabet[random.nextInt(alphabet.length)]);
}
return out.toString();
}
}
]]>