Audiosignalverarbeitung für Videokonferenzsysteme

Abstract. In this paper, we reconsider the notion of plaintext awareness. We present a new model for plaintext-aware encryption that is both natural and useful. We achieve plaintext-aware encryption without random oracles by using a third party. However, we do not need to trust the third party: even when the third party is dishonest, we still guarantee security against adaptive chosen ciphertext attacks. We show a construction that achieves this definition under general assumptions. We further motivate this achievement by showing an important and natural application: giving additional real-world meaningfulness to the DolevYao model. 1 Introduction In this paper, we put forward and implement a new notion of plaintext-aware encryption that is both natural and useful. A Beautiful but Controversial Notion. As insightfully introduced by Bellare and Rogaway [4] (see also [2] for refinements), an encryption scheme is plaintext-aware (PA) if, whenever an adversary creates a ciphertext, he must "know " its corresponding plaintext