A public library in New Hampshire is allowing the anonymous Internet browsing network Tor to use its servers. Tor relies on a layers of computers to hide the identity of its users. The Department of Homeland Security raised concerns about the decision because Tor can be used to hide illegal activity. But last night the library in Lebanon, N.H., decided the good outweighed the bad. Tor can also be used by people living in repressive regimes to communicate without government oversight.