Toward constant size CCA-secure multi-hop proxy re-encryption

Blaze et al. in 1998 introduced the concept of proxy re-encryption, which allows a proxy to transform a ciphertext computed under Alice´s public key into one that can be opened under Bob´s decryption key. But until now, the problem of constructing a constant-size CCA-secure multi-hop proxy re-encryption scheme remain open. In this paper, we try to solve this open problem by presenting a somewhat constant-size CCA-secure multi-hop proxy re-encryption scheme.