DDos Attack against Proxy in PRE and PRS

In 1998, Blaze, Bleumer, and Strauss proposed new kind of cryptographic primitives called proxy reencryption (PRE) and proxy re-signature (PRS) [2]. In proxy re-encryption, a proxy can transform a ciphertext computed under Alice’s public key into one that can be opened under Bob’s decryption key. In proxy re-signature, a proxy can transform a signature computed under Alice’s secret key into one that can be verified by Bob’s public key. In 2005, Ateniese et al proposed a few new re-encryption schemes and discussed its several potential applications especially in the secure distributed storage [6]. In 2006, they proposed another few proxy re-signature schemes and also discussed its several potential applications [7]. They predicated that proxy re-encryption and proxy re-signature will play an important role in our life. Since then, researchers are sparked to give new lights to this area. Many excellent schemes have been proposed. In this paper, we introduce a new attackDDos attack against proxy in the proxy recryptography. Although this attack can also be implemented against other cryptographic primitives, the danger caused by it in proxy re-cryptography seems more serious. We revisit the current literature, paying attention on their resisting DDos attack ability. We suggest a solution to decline the impact of DDos attacking. Also we give a new efficient reencryption scheme which can achieve CCA2 secure based on Cramer-Shoup encryption scheme and prove its security. We point out this is the most efficient proxy re-encryption schemes for the proxy which can achieve CCA2 secure in the literature. At last we give our conclusions with hoping researchers give more attention on this attack.