Single-word verb for "to keep private/confidential"

What would be a single-word verb for 'to keep private/confidential'?

My first thought was the verb "to privatise" but it doesn't connote this.

One can classify information: designate (documents or information) as officially secret or to which only authorized people may have access; to limit the availability of (information, a document, etc.)

one can secrete or secretize (very few uses) used by some, such as the attorney discussing the ethics of keeping information from the public: Why Lawyers Keep Secrets About Public Harm

One can conceal information, suppress it, hide it, etc.

Try the phrasal verb "hush up": to keep from public knowledge : suppress (hush the story up)

http://www.merriam-webster.com/dictionary/hush

The word protect could work for this, depending on context. I work in protecting data and information and this is the term we use.