You can also look up the recent course and usually get updated lecture notes too, often course calendars are available at MIT and not locked for student authentication http://css.csail.mit.edu/6.858/2015/schedule.html

Speaking of Prof. Zeldovich he's releasing this traffic analysis resistant messenging scheme with some grad students in October http://people.csail.mit.edu/nickolai/papers/vandenhooff-vuvu...