Client-side encryption is the cryptographic technique of encrypting data on the sender's side, before it is transmitted to a server such as a cloud storage service. [1] Client-side encryption features an encryption key that is not available to the service provider, making it difficult or impossible for service providers to decrypt hosted data. Client-side encryption allows for the creation of applications whose providers cannot access the data its users have stored, thus offering a high level of privacy. [1] Those applications are sometimes marketed under the misleading term "zero-knowledge". [2]
Client-side encryption seeks to eliminate the potential for data to be viewed by service providers (or third parties that compel service providers to deliver access to data), client-side encryption ensures that data and files that are stored in the cloud can only be viewed on the client-side of the exchange. By remaining encrypted through each intermediary server, client-side encryption ensures that data retains privacy from the origin to the destination server. [3] This prevents data loss and the unauthorized disclosure of private or personal files, providing increased peace of mind for its users. [1]
Current academic scholarship as well as recommendations by industry professionals provide much support for developers to include client-side encryption to protect the confidentiality and integrity of information. [4] [5] [6]
Examples of cloud storage services that provide client-side encryption are Tresorit, MEGA and SpiderOak. As of February 2016, neither Apple iCloud, [1] [7] [8] or Dropbox [9] provide client-side encryption. Google Drive and Google Docs [10] released client-side encryption in 2021 thereby becoming the first cloud productivity suite ever and the first major cloud storage platform to productionize client-side encryption. Google followed up by releasing client-side encrypted versions of Google Meet, Google Calendar, and Gmail. [11] As of January 2023, Google Workspace Client-side encryption is not yet available to free users.