@inproceedings{karameESORICS10,
 author = {Karame,, Ghassan and \v{C}apkun,, Srdjan},
 title = {Low-Cost Client Puzzles based on Modular Exponentiation},
 booktitle = {Proceedings of ESORICS (European Symposium on Research in Computer Security)},
 year = {2010}
}