Improved proxy re-encryption scheme for symmetric key cryptography

A proxy re-encryption scheme is a scheme that can be executed by a semi-trusted proxy, so that we can convert a ciphertext encrypted with a key to another ciphertext without allowing the proxy to access the plaintext. A method to implement a secure proxy re-encryption is by first converting the plaintext to an intermediate form by using an all or nothing transform (AONT). In this paper, we describe an improved proxy re-encryption scheme for symmetric cipher by advocating the usage of a variant of the AONT function in the proxy re-encryption scheme. We show that the scheme secure under Chosen Plaintext Attack (CPA) for all possible types of attackers.