Cloud computing offers a new way of services by re-arranging various resources and providing them to users based on their demands. It also plays an important role in the next generation mobile networks and services (5G) and Cyber-Physical and Social Computing (CPSC). Storing data in the cloud greatly reduces storage burden of users and brings them access convenience, thus it has become one of the most important cloud services. However, cloud data security, privacy and trust become a crucial issue that impacts the success of cloud computing and may impede the development of 5G and CPSC. First, storing data at cloud increases the risk of data leakage and unauthorized access. Second, cloud data centers are becoming the targets of attacks and intrusions, which challenge cloud data security. Third, data management operations, such as data storage, backup, migration, deletion, update, search, query and access in the cloud may not be fully trusted by its owners. Data owners should preferably audit the trustworthiness of data management. Any sources of intrusions and attacks should be able to be detected and tracked. The above requirements actually introduce a big security challenge, especially for big data storage and management. Fourth, data process and computation in the cloud could disclose the privacy of data owners or related entities to unauthorized parities. How to authorize cloud data process and protect data processing result is another interesting and significant research topic. Cloud data security, privacy and trust are indeed becoming key issues that impact the success of cloud computing. Cryptography is widely applied to ensure data security, privacy and trust in cloud computing. But existing solutions are still imperfect and inefficient, thus impractical. Storing encrypted data in the cloud makes it hard to perform auditing on data management although the risk of privacy leakage is greatly reduced. Key management for access control and revocation introduces additional computation and communication costs. In addition, operations such as fusion, aggregation, and mining on encrypted data are still impractical to be deployed due to high computation complexity and inefficiency. Cryptography in cloud computing promises many novel solutions and at the same time, many challenges are yet to be overcome. This special issue aims to bring together researchers and practitioners to discuss various aspects of cryptography and data security in cloud computing, explore key theories, investigate technology enablers, develop significant applications and innovate new solutions for overcoming major challenges in this exciting research area. This special issue collects 15 articles that cover original unpublished research illustrative of “Cryptography and Data Security in Cloud Computing” from over 60 submissions after a very rigorous review process. We classify them into four categories and briefly introduce them as below.