information
The hard drives did not contain any classified information.
National security could be harmed if classified information is disclosed.
He pleaded guilty to the charge of mishandling classified information.
MI6 is investigating claims that she passed classified information to a foreign government.
She was interrogated, but refused to reveal any classified information.

SMART Vocabulary: related words and phrases

Secrecy and privacy
anonymity
anonymization
anonymize
anonymous
anonymously
data protection
dead men tell no talesidiom
dissimulate
dissimulation
down-low
on the quietidiom
privacy
privacy settings
private
privately
under wrapsidiom
undisclosed
unrevealed
unsourced
unstated