Cloud Storage always encrypts your data on the server side, before it is written to disk, at no additional charge. Besides this standard, Google-managed behavior, there are additional ways to encrypt your data when using Cloud Storage. Below is a summary of the encryption options available to you:
Server-side encryption: encryption that occurs after Cloud Storage receives your data, but before the data is written to disk and stored.
Customer-supplied encryption keys: You can create and manage your own encryption keys. These keys act as an additional encryption layer on top of the standard Cloud Storage encryption.
Customer-managed encryption keys: You can manage your encryption keys, which are generated for you by Cloud Key Management Service. These keys act as an additional encryption layer on top of the standard Cloud Storage encryption.
Client-side encryption: encryption that occurs before data is sent to Cloud Storage. Such data arrives at Cloud Storage already encrypted but also undergoes server-side encryption.