@UNPUBLISHED{vaha-sipila-2000,
author = "Antti V\"ah\"a-Sipil\"a",
title = "Ciphering in GPRS and UMTS: encryption in 3G packet data networks",
year = "2000",
note = "Course essay, Tampere University of Technology",
url = "http://www.iki.fi/avs/gprs-umts-crypto-revised.pdf"
}