function stringRot13( aString )
{
	var b;
	var t;
	var dst = new String( '' );
	var len = aString.length;

	if( len > 0 )
	{
		for( var ctr=0; ctr < len; ctr++ )
		{
			b = aString.charCodeAt( ctr );
			if( ( (b>64) && (b<78) ) || ( (b>96) && (b<110) ) )
			{
				b = b + 13;
			}
			else
			{
				if( ( (b>77) && (b<91) ) || ( (b>109) && (b<123) ) )
				{
					b = b - 13;
				}
			}
			
			t = String.fromCharCode( b );
			dst = dst.concat( t );
		}
	}

	return dst;
}