Redis, an open-source, in-memory data structure store, is one of the most popular choices for building NoSQL databases. However, one major stumbling block for using Redis is that it does not come with any of its own encryption features.
Of course, any enterprise-class database must be able to guarantee the security of the information stored within it. If your database may be accessible by untrusted parties, you will need to develop your own encryption capabilities, enveloping data within an encryption protocol.