The contribution of this paper is three-fold. First, we provide a formal model of erasable memory. A memory device allows a user to store, retrieve, and delete data, and it is characterised by a leakage function defining the extent to which erased data is still accessible to an adversary.
Second, we investigate how the erasability of such memories can be amplified. We provide a number of constructions of memories with strong erasability guarantees from memories with weaker guarantees. One of these constructions of perfectly erasable memories from imperfectly erasable ones can be considered as the prototypical application of Canetti et al.'s All-or-Nothing Transform (AoNT). Motivated by this construction, we propose some new and better AoNTs that are either perfectly or computationally secure. These AoNTs are of possible independent interest.
Third, we show (in the constructive cryptography framework) how the construction of erasable memory and its use in cryptographic protocols (for example to achieve adaptive security) can naturally be composed to obtain provable security of the overall protocol.Category / Keywords: foundations / composable security, all or nothing transforms, Original Publication (in the same form): Security and Cryptography for Networks Volume 9841 of the series Lecture Notes in Computer Science pp 104-125