Viivo

Viivo is a free service that lets you easily secure and encrypt your Dropbox files and folders. Now your encrypted data is safe to share with your friends, family and co-workers. From PKWARE, Viivo has been engineered for you to Cloud in Confidence.
Viivo is easy to use. In fact, if you know how to use Dropbox, then you already know how to use Viivo. 
To get the most out of Viivo:
1. Download the Viivo app to your iPhone and iPad
2. Download Viivo to your PC/Laptop
3. Encrypt on Desktop and decrypt your Dropbox files on iPhone and iPad!
That’s it. Click on the install button to get started.
PKWARE’s current security products and services are used in billions of transactions by millions of customers everyday-including some of the world’s largest financial institutions, accounting firms, banks, and law firms in order to store, share and send confidential information with state-of-the-art security. From these deep roots in encryption technology, Viivo was built to make sharing, exchanging, and securing your data in the Cloud safe.