Each Kit you create can be encrypted, which will encrypt all of the data contained within that Kit. Once you encrypt a Kit, it cannot be changed to unencrypted.
Step 1: When editing your Kit's details, choose Encrypt with WitCrypt™
Step 2: Select a WitCrypt key or create a new one
Once you have encrypted your Kit, all content posted in Posts, Tasks, and Calendar will be encrypted. Anything posted before encryption will not be encrypted.