under wraps
keep a lid on
cryptadia
hiding
concealment
concealing
secret
under the covers
hush up
on the down-low
closehanded
closet
secrecy
keep from
on the hush
darkness
stall
secretiveness
silence
subterranean
cloakedly
confidentiality
closehandedness
dark
off-the-record
backstage
hypersecrecy
on the QT
sensitive
in secret
on the Q.T.
secretly
let the cat out of the bag
secernent
sub rosa
semisecrecy
confidence
mum
under one's hat
hugger-mugger
hidness
ultrasecret
occulted
oversecrete
keep shady
crypto-
in petto
undisclosed
underwrapped
keep quiet