1. We propose a new uniqueness requirement of split-state codes which states that it is computationally hard to find two codewords C = (X0;X1) and C0 = (X0;X1') such that both codewords are valid, but X0 is the same in both C and C0. A simple attack shows that uniqueness is necessary to achieve continuous non-malleability in the split-state model. Moreover, we illustrate that none of the existing constructions satisfies our uniqueness property and hence is not secure in the continuous setting.
2. We construct a split-state code satisfying continuous non-malleability. Our scheme is based on the inner product function, collision-resistant hashing and non-interactive zero-knowledge proofs of knowledge and requires an untamperable common reference string.
3. We apply continuous non-malleable codes to protect arbitrary cryptographic primitives against tampering attacks. Previous applications of non-malleable codes in this setting required to perfectly erase the entire memory after each execution and and required the adversary to be restricted in memory. We show that continuous non-malleable codes avoid these restrictions.Category / Keywords: non-malleable codes, split-state, tamper-resilience Original Publication (with minor differences): IACR-TCC-2014 Date: received 4 Mar 2014 Contact author: pratyay85 at gmail com Available format(s): PDF | BibTeX Citation Version: 20140304:211406 (All versions of this report) Discussion forum: Show discussion | Start new discussion