Answer:

DECODER

Answer	Crossword Clue
DECODER	Cryptography expert
DECODER	Kind of promotional ring once offered by Ovaltine
DECODER	Cracker?

DECODER	Cipher breaker
DECODER	Certain cracker
DECODER	Cryptanalyst.
DECODER	Worker of cryptograms.
DECODER	Cryptography man
DECODER	C.I.A. tool
DECODER	Cryptographer's device
DECODER	One who gets the message

DECODER	Reader of secret messages
DECODER	Kind of ring
DECODER	One gaining intelligence, maybe
DECODER	Type of ring