A company is considering moving its database application to a public cloud provider.

 Encryption is the process of transforming data into an unreadable format using a secret key or algorithm. Encryption is the best way to address the requirement of data confidentiality, as it ensures that only authorized parties can access and understand the data, while unauthorized parties cannot. Encryption can protect data at rest, in transit, and in use, which are the three possible states of data in cloud computing environments1. Encryption can also help comply with various regulations and standards that require data protection, such as GDPR, HIPAA, or PCI DSS2.

Authorization, validation, and sanitization are not the best ways to address the requirement of data confidentiality, as they do not provide the same level of protection as encryption. Authorization is the process of granting or denying access to data or resources based on the identity or role of the user or system. Authorization can help control who can access the data, but it does not prevent unauthorized access or leakage of the data3. Validation is the process of verifying the accuracy, completeness, and quality of the data. Validation can help ensure the data is correct and consistent, but it does not prevent the data from being exposed or compromised4. Sanitization is the process of removing sensitive or confidential data from a storage device or a data set. Sanitization can help prevent the data from being recovered or reused, but it does not protect the data while it is stored or processed5. References: Data security and encryption best practices; An Overview of Cloud Cryptography; What is Data Validation? | Talend; Data Sanitization - an overview | ScienceDirect Topics; What is Encryption? | Cloudflare.