A Covert Communication Method Adapted to Social Media Based on Time Modulation of Bullet Comments

Consumers often have the need to use social media to transmit secret information, but such communication often faces distortion due to lossy compression and limited sending frequency. In order to solve these issues, this paper proposes a covert communication method based on the time modulation of online video bullet comments. Bullet comment is a kind of time-anchored on-screen comment, which is a popular feature for online video platforms. The proposed method converts the absolute time and relative time of the bullet comments to carry the index value of the loaded bullet comments and encrypted characters. The receiver converts the time information of the obtained bullet comments into index values and uses them to extract the secret message. The experimental results show that the proposed method is suitable for multiple online video platforms. Compared with the existing covert communication methods based on social media, the secure operation frequency of the proposed method is at least 9.06 times higher when sending a secret message of the same length. The security of the proposed method is evaluated by the metrics designed according to the characteristics of the large-scale bullet comments.