noun
steganography
Technical term for hiding information within other non-secret data or media, such as embedding a message inside an image file.
ステガノグラフィーは、画像や音声ファイルに秘密のメッセージを埋め込む技術です。
Steganography is a technique for embedding secret messages in image or audio files.
暗号 (cipher/code) focuses on making a message unreadable without a key, while ステガノグラフィー hides the very existence of the message.
Borrowed from English 'steganography', ultimately from Greek steganos (covered) + graphia (writing).