Covert Communication for Dual Images with Two-Tier Bits Flipping

Data hiding in digital images is a potent solution for covert communication, embedding sensitive data into cover images. However, most existing methods are tailored for one-to-one scenarios, which present security risks. To mitigate this vulnerability, we introduce an innovative one-to-two data hiding scheme that employs a two-tier bit-flipping strategy to embed sensitive data in dual images. This process produces two stego images which are then transmitted to two distinct recipients who cannot extract any sensitive data alone. The sensitive data can only be extracted when the two recipients trust each other. Through this method, we can secure the stego images. The experimental results illustrate that our method achieves an excellent data payload while maintaining high visual quality.