Downloading copyrighted images, music, video and documents for free may soon get tougher. Elisar Software, a venture-backed startup in Albuquerque, N.M., has developed software intended to protect digital content from being copied and distributed illegally. Co-founder Greg Heileman says the system, expected to come on the market by year’s end, combines three existing protection technologies. One software component encrypts the content for online display. A second component decrypts it for viewing and places the material in a “secure container” that prevents copying. When content is sold, it is marked with a hidden “fingerprint” that enables its usage to be traced. The software works with images, music, text and video, and can be used with standard viewers such as Adobe Acrobat.