sub rosa  a. & adv.  (Of communication, consultation, etc.)  In confidence, under express or implied pledge of secrecy.
[L, lit. under the rose, as emblem of secrecy]  

By the mid 1990s I was still doing Liquid City but also looking at how I could work with one of the most traditional and well-documented of subjects: the nude figure. As usual, what I was looking for only began coming into focus once I got to work. And what kept recurring were qualities that created a tension with the sensuality of form—qualities revolving around an uncertain opaqueness, an evasiveness, issues planted themselves firmly in my emotional life at the time. What helped me along was discovering—initially through some lovely Polaroid accidents and later by conscious refinement—a set of techniques that could both obfuscate and meld the formal elements of the picture. Rather than irradiating the subject, these interventions shaped the image into something darkly evanescent—a dreamlike aura that mirrored the sense of life, including erotic life, that I would find myself slipping in and out of.... 
— Frank Rodick, 2017