MD5 hashing: Encodes a string : MD5 Message Digest algorithm  « Security « Java Tutorial

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3. MD5 Message Digest algorithm

/*
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 * This file creation date: Mar 29, 2003 / 1:15:50 AM
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 * http://www.jforum.net
 */
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;



/**
 * Encodes a string using MD5 hashing 
 * 
 * @author Rafael Steil
 * @version $Id: MD5.java,v 1.7 2006/08/23 02:13:44 rafaelsteil Exp $
 */
public class MD5 
{
  /**
   * Encodes a string
   * 
   * @param str String to encode
   * @return Encoded String
   * @throws NoSuchAlgorithmException
   */
  public static String crypt(String str)
  {
    if (str == null || str.length() == 0) {
      throw new IllegalArgumentException("String to encript cannot be null or zero length");
    }
    
    StringBuffer hexString = new StringBuffer();
    
    try {
      MessageDigest md = MessageDigest.getInstance("MD5");
      md.update(str.getBytes());
      byte[] hash = md.digest();
      
      for (int i = 0; i < hash.length; i++) {
        if ((0xff & hash[i]) < 0x10) {
          hexString.append("0" + Integer.toHexString((0xFF & hash[i])));
        }       
        else {
          hexString.append(Integer.toHexString(0xFF & hash[i]));
        }       
      }
    }
    catch (NoSuchAlgorithmException e) {
      throw new RuntimeException("" + e);
    }
    
    return hexString.toString();
  }
}