@article{CAIA-JP-070700A,
    title = {{A Survey of Covert Channels and Countermeasures in Computer Network Protocols}},
    author = {Sebastian Zander and Grenville Armitage and Philip Branch},
    month = {July},
    year = {2007},
    pages = {44-57},
    volume = {9},
    number = {3},
    journal = {IEEE Communications Surveys \& Tutorials},
    doi = {10.1109/COMST.2007.4317620},
    url = {http://dx.doi.org/10.1109/COMST.2007.4317620}
}