A method for performing unidirectional proxy re-encryption includes generating a first key pair comprising a public key (pk) and a secret key (sk) and generating a re-encryption key that changes encryptions under a first public key pka into encryptions under a second public key pkb as rkA→B. The method further includes performing one of the group consisting of encrypting a message m under public key pka producing a ciphertext ca, re-encrypting a ciphertext ca using the re-encryption key rkA→B that changes ciphertexts under pka into ciphertexts under pkb to produce a ciphertext cb under pkb, and decrypting a ciphertext ca under pka to recover a message m. The method also includes encrypting a message m under a public key pk producing a first-level ciphertext c1 that cannot be re-encrypted, and decrypting a first-level ciphertext c1 using secret key sk.