With the quick evolution of information technologies, computer networks, and digital imaging technology over the past decades, the modification of media has been greatly leveraged with tools easily available. Meanwhile, the use of media also made sensitive information available to potential eavesdroppers. The credibility of digital media has thus decreased and the demand for new technologies has emerged. Many techniques have been introduced to study their intrinsic principles.

Nowadays, many challenges emerge. First, the traditional steganography is now seriously threatened by machine learning based steganalysis. Therefore, new types of steganography, for example, constructive steganography, are urgently needed to combat state-of-the-art steganalysis. Second, when transmitting stego media over social networks, the servers always modify the covers, for example, changing the resolution or recompressing the multimedia. Since the traditional steganography techniques are always fragile, robust steganography is now required. Third, the lack of efficient techniques of privacy preserving is now preventing the development of cloud computing. For example, how to encrypt a JPEG image for cloud storage users and how to reliably solve a complicated computation by outsourcing are still open questions.

This special issue focuses on active research areas on multimedia security, such as novel types of steganography, privacy preserving on cloud computing, multimedia tampering detection, and source device identification. We invite the authors to submit original research articles covering theoretical aspects models and solutions to stimulate the development of multimedia security.

Potential topics include but are not limited to the following:

• Latest techniques of steganography and steganalysis
• Recent developments in multimedia forensics
• Advances in reversible data hiding in plaintext or ciphertext multimedia
• Reliable computing and outsourcing of multimedia
• Novel techniques of multimedia watermarking
• Privacy preserving of multimedia