The Committee to Protect Journalists says that online censorship in Ethiopia (focused on political protests) is on the rise and becoming increasingly more sophisticated.

This year, the strictures tightened again, with what many observers believe was the rollout of a far more pervasive and sophisticated blocking system. Starting in April, additional bloggers and reporters noted that their sites were being filtered, including De Birhan, a news and analysis blog that was blocked on April 21, when a large number of sites were inaccessible for a few days.

According to informal surveys taken by one exiled Ethiopian journalist, the sites temporarily blocked have been joined by a growing list of smaller exile blogs and news services, including individual Facebook pages like “We Are All Eskinder Nega.” Then, in mid-May, the Tor projectreported that Ethiopia had successfully begun blocking its free anonymizing and anti-censorship services. Given that Tor encrypts, and to a certain level, disguises its traffic as normal secure Web traffic, the implication is that Ethiopia has been rolling out censorship systems that can detect specific Internet protocols and block them. (Tor’s traffic in Ethiopia is still not back to pre-May levels).

Previously the country blocked a number of exile news sites from being accessed in Ethiopia. However, the censorship, while strong, is not fully consistent. The country, for example, doesn’t block SSL-encrypted Facebook pages.