conundrum
arcanum
backroom
cagey
character
cipher
classified
closeup
code
confidential
crux
cypher
dancing men
decipher
decipherment
decoding
discharge
encrypted
enigma
epistle
favor
flush
lens
letter
loupe
magnifier
magnifying glass
message
missive
mystery
old
paper
privacy
privity
puzzle
reserved
reticent
riddle
scroll
secrecy
secret
secretive
sheet
sign
sunk
symbol
transcript
vintage
writing