Locally Decodable and Updatable Non-Malleable Codes and Their Applications

Non-malleable codes, introduced as a relaxation of error-correcting codes by Dziem-bowski, Pietrzak and Wichs (ICS ’10), provide the security guarantee that the message contained in a tampered codeword is either the same as the original message or is set to an unrelated value. Various applications of non-malleable codes have been discovered, and one of the most significant applications among these is the connection with tamper-resilient cryptography. There is a large body of work considering security against various classes of tampering functions, as well as non-malleable codes with enhanced features such as leakage resilience. In this work, we propose combining the concepts of non-malleability, leakage resilience, and locality in a coding scheme. The contribution of this work is three-fold: 1. As a conceptual contribution, we define a new notion of locally decodable and updatable non-malleable code that combines the above properties. 2. We present two simple and efficient constructions achieving our new notion with dif-ferent levels of security