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Auflistung nach Autor:in "Henrich, Christian"

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  • Konferenzbeitrag
    Social key exchange network - from ad-hoc key exchanges to a dense key network
    (INFORMATIK 2011 – Informatik schafft Communities, 2011) Achenbach, Dirk; Förster, David; Henrich, Christian; Kraschewski, Daniel; Müller-Quade, Jörn
    Security of public key cryptography is steadily threatened by advancements in algorithmics and computing power. In this work we propose a novel approach to long-term secure key exchange based on security assumptions that are independent of strong complexity assumptions. We present a key propagation scheme that sets up a network of distributed keys. Whenever two parties meet, they exchange new keys (e.g. using near field communication) and pass on all keys received so far. This establishes a dense key network growing and spreading with each meeting of protocol participants. Even two parties that have never met in person can use this network to obtain a common secret. A notable security feature of our scheme is the anonymity of the established keys, making it hard for an adversary to track movements of protocol participants.
  • Konferenzbeitrag
    Towards secure cloud computing through a separation of duties
    (INFORMATIK 2011 – Informatik schafft Communities, 2011) Henrich, Christian; Huber, Matthias; Kempka, Carmen; Müller-Quade, Jörn
    Cloud Computing offers many opportunities but also introduces new risks. A user outsourcing his database into the cloud loses control over this data. While the service provider often secures the data against external threats using standard techniques, the service providers themselves have to be trusted to ensure privacy. This work proposes a novel approach to provide security for database services without the need to trust the provider. We suggest employing a separation of duties by distributing critical information and services between two or more providers in a way that the confidentiality of a database can only be compromised if all providers are corrupted and work together. We also present a formal security notion for such a database.