This paper researches Proxy Re-encryption( PRE) technology under the Certificateless Public Key Cryptography( CL-PKC),gives a formal definition and security model for certificateless PRE system and construct a newcertificateless PRE scheme. The newscheme is proved secure against chosen plaintext attack in the Random Oracle Model( ROM). With the help of the proposed scheme,cloud service providers can transform ciphertexts encrypted under a user's public key into different ciphertexts that can be decrypted by...