ded abstract of this paper appears in PKC 2009, S. Jarecki, G. Tsudik (Eds.), volume 5443 of LNCS, pp. 357-376, Sringer-Verlag, 2009. CCA-Secure Proxy Re-Encryption without Pairings Jun Shao1,2 Zhenfu Cao1 chn.junshao@gmail.com zfcao@cs.sjtu.edu.cn 1 Department of Computer Science and Engineering Shanghai Jiao Tong University 2 College of Information Sciences and Technology Pennsylvania State University In a proxy re-encryption scheme, a semi-trusted proxy can transform a ciphertext under Alice's public key into another ciphertext that Bob can decrypt. However, the proxy cannot access the plaintext. Due to its transformation property, proxy re-encryption can be used in many applications, such as encrypted email forwarding. In this paper, by using signature of knowledge and Fijisaki-Okamoto conversion, we propose a proxy re-encryption scheme without pairings, in which the proxy can only transform the ciphertext in one direction. The proposal is secure against chosen ciphertext att...