This document discusses various cryptographic techniques for securing data shared over cloud computing. It begins with an introduction to cloud computing and the types of cloud services. It then discusses some critical threats to cloud security like unauthorized access, lack of integrity checks, and denial of service attacks. The document analyzes popular encryption algorithms like RSA, AES, DES, Blowfish and IDEA that can be applied for cloud data security. It provides details on how each algorithm works and compares their characteristics. The document concludes that a multilevel security architecture applying multiple encryption algorithms is needed to securely transmit data over the cloud.