Multimedia Security: Encryption, Watermarking, and Distribution Technologies and Applications

Abstract

With the development progress of wireless communications and networking technologies, the transmission opportunities of multimedia data become increasing. Because of the planarity and diversity of multimedia, and the increasing rate of wireless network popularity, the sharing and exchanging actions among different users are common. However, during the transmission process, if the multimedia data is not properly protected, i.e. if the multimedia security technologies are not properly developed, multimedia content would be accessed and shared without any limitation, forcing the copyright of the multimedia content owner. In this dissertation, the multimedia applications and technologies would be widely discussed, especially multimedia encryption, watermarking, and distribution applications and technologies. In this dissertation, the recent most challenging problems in multimedia security would be addressed, discussed, and properly dealt with.

In this dissertation, the multimedia security issue is discussed from the first defense line: multimedia encryption. Because the protected encrypted multimedia data would be distributed over the error-prone network environment, a media-hash based video error resilient technique is proposed. Next, the second defense line, multimedia watermarking, is addressed. A robust image watermarking technique against geometric distortions and watermark estimation attack (WEA) is proposed. In addition, a temporal re-synchronization technique for video watermarking is discussed to improve the robustness. While the two defense lines for multimedia security are well-developed, a proper secure multimedia distribution framework is necessary. An advanced access control system (AACS)-compatible joint encryption and fingerprinting technique is proposed to form a proper framework. Some security issues, challenges, and solutions are addressed.

Media encryption technologies actively play the first line of defense in securing the access of multimedia data. Traditional cryptographic encryption can achieve provable security but is unfortunately sensitive to a single bit error, which will cause an unreliable packet to be dropped creating packet loss. In order to achieve robust media encryption, the requirement of error resilience can be achieved with error-resilient media transmission. This dissertation proposes a video joint encryption and transmission (video JET) scheme by exploiting media hash-embedded residual data to achieve motion estimation and compensation for recovering lost packets, while maintaining format compliance and cryptographic provable security. Interestingly, since video block hash preserves the condensed content to facilitate search of similar blocks, motion estimation is implicitly performed through robust media hash matching -- which is the unique characteristic of our method.

The second defense line of multimedia protection is watermarking. The major disadvantage of existing watermarking methods is their limited resistance to extensive geometric attacks. In addition, we have found that the weakness of multiple watermark embedding methods that were initially designed to resist geometric attacks is their inability to withstand the watermark-estimation attacks (WEAs), leading to reduce resistance to geometric attacks. In view of these facts, this dissertation proposes a robust image watermarking scheme that can withstand geometric distortions and WEAs simultaneously. Our scheme is mainly composed of three components: (i) robust mesh generation and mesh-based watermarking to resist geometric distortions; (ii) construction of media hash-based content-dependent watermark (CDW) to resist WEAs; and (iii) a mechanism of false positive-oriented watermark detection, which can be used to determine the existence of a watermark so as to achieve a trade-off between correct detection and false detection.

In addition, synchronization for video watermarking is a challenging problem. We propose a novel temporal synchronization method for video watermarking by matching the profile statistics. The profile statistics, represented by the characteristic parameters such as position mean and variance in x- and y-directions, of a frame in a video sequence can easily be calculated and sent as the side information to the receiver. At the receiving end, temporal attacks such as transposition, dropping, and insertion can be detected by comparing the side information and the characteristic parameters calculated from the received video.

While the two defense lines for multimedia security are well-developed, a proper secure multimedia distribution framework is necessary. In this dissertation, a new multimedia joint encryption and fingerprinting (JEF) scheme embedded into the advanced access control system (AACS) is proposed. AACS is selected because it has been the leading technology in access control developed by many significant companies for multimedia distribution. In this AACS-compatible JEF system, many attack points exist and can be explored to defend it. Furthermore, multiple attack points can form multi-point collusion attacks, which also engage the proposed system. In this paper, (i) we propose multimedia encryption at different points to resist some attacks points; (ii) we propose rewritable fingerprint embedding (RFE) to deal with some multi-point collusion attacks; (iii) we design SPSM to evaluate the degree of security which multiple encryptions are applied.

Key words ¾ Multimedia Security, Encryption, Watermarking, Distribution