Ключевые слова: background, business, classified, communicate, communication, computer, concept, confidential, covert, crime, data, document, espionage, government, hush, information, intelligence, key, lock, message, mysterious, mystery, office, open, privacy, private, protection, restricted, restriction, safety, secrecy, secret, secure, security, share, special, spy, spying, stamp, system, technology, top, top secret, undercover, unknown, word, yellow,