COMPRESS MULTIPLE CIPHERTEXTS USING ELGAMAL ENCRYPTION SCHEMES

Abstract

In this work we deal with the problem of how to squeeze mul- tiple ciphertexts without losing original message information. To do so, we formalize the notion of decomposability for public-key encryption and investigate why adding decomposability is challenging. We construct an ElGamal encryption scheme over extension fields, and show that it sup- ports the efficient decomposition. We then analyze security of our scheme under the standard DDH assumption, and evaluate the performance of our construction.