An Improved Exponential ElGamal Encryption Scheme with Additive Homomorphism

Homomorphic encryption is a special encryption scheme which allows an untrusted third party to operate directly on the encrypted data. ElGamal encryption scheme is an early homomorphic encryption scheme with multiplicative homomorphism. We analysed the security of standard ElGamal encryption scheme by constructing reasonable interaction between attacker and random oracle. By associating the quadratic residue property of plaintext with the corresponding ciphertext, we found that the ElGamal encryption scheme was not secure enough under the attack of chosen plaintext. To solve this problem, we proposed a new homomorphic encryption scheme which we called exponential ElGamal, and tested its efficiency and security