An implementation of a decryption of a password file inside an ANT task extending the AbstractTeamBuildTask from RTC would look like:

if (getPasswordFile() != null)
{
    logger.info("Detected password file. Decrypting password");

	logger.info(String.format("password file is [%s]", getPasswordFile().toString()));
	
	final Properties properties = new Properties();
	final FileInputStream in = new FileInputStream(getPasswordFile());
    properties.loadFromXML(in);
    in.close();
	  
    for (Object key : properties.keySet())
    {
	logger.info(String.format("Key = [%s]", key.toString()));
    }
	  
    setPassword(ObfuscationHelper.decryptString(properties.getProperty("password")));
}

see above,

here is a sample pgm to encryt and decrypt the string..

package com.sd.tools;

import java.io.UnsupportedEncodingException;
import java.security.GeneralSecurityException;

import com.ibm.team.repository.common.util.ObfuscationHelper;

public class EncodePassword
{

    /**
     * @param args
     */
    public static void main(String[] args)
    {
        // TODO Auto-generated method stub
        if(args.length==1)
        {
                String enpw = ObfuscationHelper.encryptString(args[0]);
                // you would use this output in any password file
                System.out.println(enpw);

                // here is how you would decrypt it for use in your application.
                // you could get this string from the commandline, or a file,
                // or a properties file (pw= string)
               String userpw=enpw;  (the encrypted or plain text password)
               try
                   {
                   // try to decrypt
                   userpw=ObfuscationHelper.decryptString(userpw);
                   }
                catch(Exception ex)
                   {
                    // nothing to do, target variable not overwritten on error
                   }
                System.out.println("pw="+userpw);
            }
        }
        else
            System.out.println("need password string");
    }

}