What is Encrypted with Files and Attachments Encryption?

Shield Platform Encyrption encrypt all files and attachments uploaded into Salesforce. The body of each file is ecrypted. If you have enabled Database Encryption, files and attachments smaller than 32K in size are stored directly within the transactional database and are under its encryption protection. Larger files are always stored as encrypted binary objects in a separate content store.

Files and Attachments Encryption shares the tenant secret used for Fields (Probabilistic) and Chatter.