Cloud-ElGamal: An efficient homomorphic encryption scheme

Thanks to several advantages offered by cloud computing, such as: reducing costs, high services scalability and flexibility. Cloud computing has become a widely adopted technology for delivering services over the Internet. However, the fear of seeing sensitive data be processed in clear has become a major barrier to cloud services adoption. Indeed, researchers have stressed a useful technique called “homomorphic encryption”, this technique allows specific type of computations to be performed on encrypted data without decrypting it The encryption schemes that support homomorphic properties are numerous; unfortunately, many attacks make these schemes insecure, especially when adopting these schemes to protect the confidentiality of outsourced data into the cloud due to the long time of storing the ciphertexts by the same key. To mitigate these drawbacks, in this paper we will suggest an enhanced version of the standard ElGamal encryption scheme which supports the multiplicative homomorphism and resists more the confidentiality attacks.