Patent ID: 8094810

Claim:
A computer implemented method for performing unidirectional proxy re-encryption comprising: generating, by a computer system, a first key pair comprising a public key (pk) and a secret key (sk), wherein said generating a key pair comprises generating a key pair of the form pk a =(Z a 1 , g a 2 ) and sk a =(a 1 , a 2 ) wherein g is a generator of a first algebraic group G 1 , wherein Z=e(g,g) is an element of a second algebraic group G 2 and wherein G 1 and G 2 are of prime order q with a bilinear map e:G 1 ×Ĝ 1 →G 2 ; generating, by a computer system, -a re-encryption key that changes encryptions under a first public key pk a into encryptions under a second public key pk b as rk A→B ; and performing, by a computer system, one of the group consisting of encrypting a message m under public key pk a producing a ciphertext c a , re-encrypting a ciphertext c a using the re-encryption key rk A→B that changes ciphertexts under pk a into ciphertexts under pk b to produce a ciphertext c b under pk b , and decrypting the ciphertext c a under pk a to recover the message m.