Multi-key leakage-resilient threshold cryptography

Abstract

With the goal of ensuring availability of security services such as encryption and authentication, we initiate the study of leakage-resilient threshold cryptography, for achieving formal security guarantee under various key-exposure attacks. A distinctive property of threshold cryptosystems is that a threshold number of secret keys are used in the main cryptographic function such as decryption or signing. Even though some existing security models allow leakages of multiple keys of different users, these keys are not used simultaneously to decrypt a ciphertext or sign a message. In this paper, we introduce the multi-key leakage-resilient security model for threshold cryptography. We also propose constructions with formal security guarantee with respect to our model, one is a dynamic threshold public key encryption scheme and another is a threshold ring signature scheme. © 2013 ACM.