The APROB Channel: Adaptive Semi-Real-Time Anonymous Communication

Anonymous communication has become a building block of network services. Besides providing anonymity, speed (and thus real-time guarantees) are becoming crucial as well. In this paper we will introduce the global delaying adversary (GDA), an active attacker who is capable of arbitrarily delaying messages, while eavesdropping on all communication channels. This type of foe is particularly relevant for inter-mix relationships, where communication between the partners is secured (by authentication and integrity protection), and delaying remains the only effective external active attacking possibility. To counter GDA, the adaptive semi-real-time APROB Channel will be introduced. It will be shown that the APROB Channel can provide a guaranteed level of anonymity under semi-real-time conditions considering that the adversary cannot obtain any additional information by delaying messages, thus this type of attack will not be reasonable.