Anti-collusion forensics of multimedia fingerprinting using orthogonal modulation.

Digital fingerprinting is a method for protecting digital data in which fingerprints that are embedded in multimedia are capable of identifying unauthorized use of digital content. A powerful attack that can be employed to reduce this tracing capability is collusion, where several users combine their copies of the same content to attenuate/remove the original fingerprints. In this paper, we study the collusion resistance of a fingerprinting system employing Gaussian distributed fingerprints and orthogonal modulation. We introduce the maximum detector and the thresholding detector for colluder identification. We then analyze the collusion resistance of a system to the averaging collusion attack for the performance criteria represented by the probability of a false negative and the probability of a false positive. Lower and upper bounds for the maximum number of colluders K(max) are derived. We then show that the detectors are robust to different collusion attacks. We further study different sets of performance criteria, and our results indicate that attacks based on a few dozen independent copies can confound such a fingerprinting system. We also propose a likelihood-based approach to estimate the number of colluders. Finally, we demonstrate the performance for detecting colluders through experiments using real images.     

Forensic analysis of nonlinear collusion attacks for multimedia fingerprinting.

Digital fingerprinting is a technology for tracing the distribution of multimedia content and protecting them from unauthorized redistribution. Unique identification information is embedded into each distributed copy of multimedia signal and serves as a digital fingerprint. Collusion attack is a cost-effective attack against digital fingerprinting, where colluders combine several copies with the same content but different fingerprints to remove or attenuate the original fingerprints. In this paper, we investigate the average collusion attack and several basic nonlinear collusions on independent Gaussian fingerprints, and study their effectiveness and the impact on the perceptual quality. With unbounded Gaussian fingerprints, perceivable distortion may exist in the fingerprinted copies as well as the copies after the collusion attacks. In order to remove this perceptual distortion, we introduce bounded Gaussian-like fingerprints and study their performance under collusion attacks. We also study several commonly used detection statistics and analyze their performance under collusion attacks. We further propose a preprocessing technique of the extracted fingerprints specifically for collusion scenarios to improve the detection performance.     

Collusion-secure and cost-effective detection of unlawful multimedia redistribution

Intellectual property protection of multimedia content is essential to the successful deployment of Internet content delivery platforms. There are two general approaches to multimedia copy protection: copy prevention and copy detection. Past experience shows that only copy detection based on mark embedding techniques looks promising. Multimedia fingerprinting means embedding a different buyer-identifying mark in each copy of the multimedia content being sold. Fingerprinting is subject to collusion attacks: a coalition of buyers collude and follow some strategy to mix their copies with the aim of obtaining a mixture from which none of their identifying marks can be retrieved; if their strategy is successful, the colluders can redistribute the mixture with impunity. A construction is presented in this paper to obtain fingerprinting codes for copyright protection which survive any collusion strategy involving up to three buyers (3-security). It is shown that the proposed scheme achieves 3-security with a codeword length dramatically shorter than the one required by the general Boneh-Shaw construction. Thus the proposed fingerprints require much less embedding capacity. Due to their own clandestine nature, collusions tend to involve a small number of buyers, so that there is plenty of use for codes providing cost-effective protection against collusions of size up to three.     

Design and Analysis of High-Capacity Anti-Collusion Hiding Codes

A new methodology for the design of high-capacity anti-collusion hiding codes in a large-scale fingerprint-based traitor tracing system is proposed in this work. We consider a hiding code of MN bits, where M bits are used as the user ID and N bits are the length of the spreading codes. Since each user is assigned one out of 2 ^M ID numbers and one out of N spreading codewords, the total number of users is equal to 2 ^M N. To accommodate an even larger number of users, we propose a shifted spreading scheme that shifts the spreading codeword circularly by a certain amount. By allowing P shifts (with P mod N), the total number of users increases from 2 ^M N to 2 ^M NP. When multiple users perform a weighted collusion attack, we show that the task of identifying colluders and their attack weights can be formulated as a user detection and channel estimation problem in a multiuser wireless communication system with a multipath fading channel. For the latter, there exist code design techniques that choose the spreading codes carefully so as to reduce multiaccess interference of users with different spreading codewords effectively. By exploiting this analogy, we develop an anti-collusion code called OSIFT (Orthogonal Spreading followed by the Inverse Fourier Transform). We compare several hiding codes in a fingerprinting system consisting of hundreds of colluders. It is demonstrated by computer simulation that, when the OSIFT code is adopted, colluders and their attack weights can be found by the proposed fingerprinting system more accurately.     

Fingerprint multicast in secure video streaming.

Digital fingerprinting is an emerging technology to protect multimedia content from illegal redistribution, where each distributed copy is labeled with unique identification information. In video streaming, huge amount of data have to be transmitted to a large number of users under stringent latency constraints, so the bandwidth-efficient distribution of uniquely fingerprinted copies is crucial. This paper investigates the secure multicast of anticollusion fingerprinted video in streaming applications and analyzes their performance. We first propose a general fingerprint multicast scheme that can be used with most spread spectrum embedding-based multimedia fingerprinting systems. To further improve the bandwidth efficiency, we explore the special structure of the fingerprint design and propose a joint fingerprint design and distribution scheme. From our simulations, the two proposed schemes can reduce the bandwidth requirement by 48% to 87%, depending on the number of users, the characteristics of video sequences, and the network and computation constraints. We also show that under the constraint that all colluders have the same probability of detection, the embedded fingerprints in the two schemes have approximately the same collusion resistance. Finally, we propose a fingerprint drift compensation scheme to improve the quality of the reconstructed sequences at the decoder's side without introducing extra communication overhead.     

一种高容量盲检测图像指纹算法

针对共谋攻击,提出了一种高容量的空域盲检测图像指纹算法.用抗共谋攻击码(ACC)调制正交基向量生成二值指纹,根据指纹状态对图像灰度值量化嵌入指纹.追踪共谋者时,首先根据待检图像像素灰度所属区间提取指纹,然后计算其与正交基向量的内积得到一新向量,对其用软阈值方式进行处理,最后追踪共谋者.指纹嵌入提取采用量化方式,是一种盲...     

A new fingerprinting scheme using social network analysis for majority attack

Digital fingerprinting is a technology to protect multimedia content from unauthorized redistribution. However, collusion attack is a cost-efficient attack for digital fingerprinting, where groups of dishonest users create a pirate copy using their copies for the purpose of attenuating or removing the fingerprints. In this paper, FCBSN, Fingerprinting Code Based on Social Networks, for coding the user’s fingerprints to resist majority attack, is proposed. The proposed scheme stems from the concept of coalition which always occurred in a social network. Different from all existing work, we explore the notion of the hierarchical community structure of social network and its intrinsic properties to assign fingerprints to users, drawing on the social relation according to the similar metric between two users. Theoretical analysis and experimental results show that the FCBSN detector outperforms the existing group detector for BS code and Tardos detector by large margins.     

Collusion-resistant fingerprinting for multimedia

Digital fingerprinting is a technology for enforcing digital rights policies whereby unique labels, known as digital fingerprints, are inserted into content prior to distribution. For multimedia content, fingerprints can be embedded using conventional watermarking techniques that are typically concerned with robustness against a variety of attacks mounted by an individual. These attacks, known as multiuser collusion attacks, provide a cost-effective method for attenuating each of the colluder's fingerprints and poses a real threat to protecting media data and enforcing usage policies. In this article, we review some major design methodologies for collusion-resistant fingerprinting of multimedia and highlight common and unique issues of different fingerprinting techniques. It also provides detailed discussions on the two major classes of fingerprinting strategies, namely, orthogonal fingerprinting and correlated fingerprinting.     

A novel fingerprinting algorithm with blind detection in DCT domain for images

A novel blind fingerprint detection scheme for images is presented in Discrete Cosine Transform (DCT) domain. Anti-Collusion Codes (ACCs) are employed to design the fingerprints, which can accommodate more users than orthogonal modulation based fingerprints with the same amount of signals. The selected DCT coefficients of the original image are quantized according to fingerprints, the standard JPEG quantization table is employed to improve the ability of anti-compression. The fingerprints were extracted without original signal's participation by judging which interval of the DCT coefficients belong to. Besides, the detection threshold is optimized automatically during tracing colluders. Experimental results show that the proposed blind fingerprint detection scheme has larger capacity and is more efficient than the existing algorithms.     

A dual watermark-fingerprint system

This article proposes a multimedia content protection system in which all copies of a protected object are identically watermarked, but each user has a distinct secret detection key that differs from the secret embedding key. An attacker with access to one detection key can fool the corresponding watermark detector but not other watermark detectors. Surprisingly, analogous to a criminal action, during this attack the attacker necessarily inserts his or her fingerprint into the modified content. Even a collusion clique of relatively large size cannot entirely remove the secret marks from the protected content by colluding their detection keys. More importantly, if the clique is not large enough, traces of the detection keys of all colluders can be detected with relatively high accuracy in the attacked clip. Our proposed watermark-fingerprint system achieves a minimum collusion size K that grows linearly with the size N of the marked object. In addition, we can augment our watermark-fingerprint system with a segmentation layer. The media content is partitioned into 5 segments, in which media players as well as forensic analyzers can reliably detect a watermark or fingerprint. Only detection keys that belong to the same segment can participate in the collusion clique. With segmentation, the minimum collusion size K grows as 0(N log N). Therefore, with or without segmentation, our watermark-fingerprint system significantly improves on the best-known asymptotic resistance to (fingerprint) collusion attacks of about O(N/sup 1/4/). Because we use a new protection protocol, comparing our system to classic fingerprint systems might seem unfair. However, such a comparison is important because the two technologies share a common goal: multimedia copyright enforcement. Our aim in this article is to characterize the collusion attacks against this system under the assumption that watermark detection is robust against signal-processing attacks on the protected object.     

Attack on Sebe, Domingo-Ferrer and Herrera-Joancomarti fingerprinting schemes

Sebe' and Domingo-Ferrer proposed in a recent letter a fingerprinting scheme that exploits the properties of dual binary Hamming codes to reduce the length of fingerprints. The authors show that this scheme is subject to an attack in which a collusion of (any) three buyers can frame an innocent buyer.     

A content security protection scheme in JPEG compressed domain

The access and distribution convenience of public networks opens a considerable content security threat when sending, receiving, and using multimedia information. In this paper, a content security protection scheme that integrates encryption and digital fingerprinting is proposed to provide comprehensive security protection for multimedia information during its transmission and usage. In contrast to other schemes, this method is implemented in the JPEG compressed domain with no transcoding or decompression, therefore, this scheme is highly efficient and suitable for multimedia information, which is seldom available in an uncompressed form. In addition, a variable modular encryption method is proposed to solve the invalid variable length coding (VLC) problem when a compressed data stream is encrypted directly. Experimental results demonstrate improved security and the efficiency provided by the proposed scheme. The experiments also demonstrate imperceptibility and collusion resistance of fingerprints.     

Digital fingerprinting codes: problem statements, constructions, identification of traitors

We consider a general fingerprinting problem of digital data under which coalitions of users can alter or erase some bits in their copies in order to create an illegal copy. Each user is assigned a fingerprint which is a word in a fingerprinting code of size M (the total number of users) and length n. We present binary fingerprinting codes secure against size-t coalitions which enable the distributor (decoder) to recover at least one of the users from the coalition with probability of error exp(-/spl Omega/(n)) for M=exp(/spl Omega/(n)). This is an improvement over the best known schemes that provide the error probability no better than exp(-/spl Omega/(n/sup 1/2/)) and for this probability support at most exp(O(n/sup 1/2/)) users. The construction complexity of codes is polynomial in n. We also present versions of these constructions that afford identification algorithms of complexity poly(n)=polylog(M), improving over the best previously known complexity of /spl Omega/(M). For the case t=2, we construct codes of exponential size with even stronger performance, namely, for which the distributor can either recover both users from the coalition with probability 1-exp(/spl Omega/(n)), or identify one traitor with probability 1.     

Multimedia transmission in fiber-optic LANs using optical CDMA

In this paper, we address the problem of multimedia transmission in fiber-optic networks. We apply the code-division multiple-access (CDMA) technique for such a network. The necessary conditions for successful operation of the network are given. It is shown that for successful operation, new families of optical orthogonal codes (OOCs) are needed which will have not only good correlation properties within one code family, but also between families of different code lengths. Some possible constructions of multimedia OOCs and the corresponding basic structure of the receiver for the multimedia network are given. Specific examples of OOCs for the case of users with two different data rates are given, and the probability of error (using the Gaussian approximation) as a function of the number of low and high rate users is calculated     

Soft-decision tracing in fingerprinted multimedia content

To protect intellectual property and distribution rights against dishonest customers in the multimedia content market, fingerprinting schemes that use error-correcting codes help identify users illegally redistributing media. This article presents a traitor-tracing algorithm that takes advantage of soft-decision decoding techniques to find all identifiable traitors.     

Design of spread spectrum multicode CDMA transport architecture formultimedia services

We investigate a new application of the well-known spread spectrum code division multiple access (SS-CDMA) techniques to multimedia services related to the development of the next-generation wireless mobile networks interconnecting with a wireline ATM-based broadband network. Such services allow users to share novel multimedia applications without any geographical restrictions. However, since the mobile radio channel has a fixed limited bandwidth, the traditional SS-CDMA system may not be sufficient to accommodate the variable bit rate (VBR) multimedia services requested by multiple mobile users simultaneously. Moreover, the traffic load at the base station can change dynamically due to the time-varying throughput requirement of these requested multimedia services. To tackle this difficulty, a multicode CDMA (MC-CDMA) technique is proposed to provide multirate multimedia services by varying the number of spreading codes assigned to each user in order to meet its throughput requirement. In MC-CDMA, a spreading code can be used to transmit information at a basic bit rate. Users (video or data) who need higher transmission rates can use multiple codes in parallel. Meanwhile, the maximum available number of codes in the MC-CDMA system is still limited. Hence, a cost-effective dynamic code allocation scheme has then been proposed to dynamically assign an appropriate number of codes to each user for achieving the maximum resource utilization for multiuser multimedia services via the mobile radio channel. Finally, a number of real multimedia titles generated from the well-known MacroMind Director are conducted to evaluate performance     

Performance of UWB SSMA using orthogonal PPM-TH over dense multipath channels

In this work we study ultra wideband (UWB) communications over dense multipath channels using orthogonal pulse position modulation (PPM) for data modulation and time-hopping (TH) for code modulation. We consider the effects of the multiple access interference (MUI) in asynchronous spread spectrum multiple access (SSMA) based on random TH codes. We use a realistic multipath channel to analyze the effects of the transmission rate in the number of users for different bit error rate (BER) values.     

Application layer forward error correction for multicast streaming over LTE networks

The next step beyond third generation mobile networks is the Third Generation Partnership Project standard, named Long Term Evolution. A key feature of Long Term Evolution is the enhancement of multimedia broadcast and multicast services (MBMS), where the same content is transmitted to multiple users located in a specific service area. To support efficient download and streaming delivery, the Third Generation Partnership Project included an application layer forward error correction (AL‐FEC) technique based on the systematic fountain Raptor code, in the MBMS standard. To achieve protection against packet losses, Raptor codes introduce redundant packets to the transmission, that is, the forward error correction overhead. In this work, we investigate the application of AL‐FEC over MBMS streaming services. We consider the benefits of AL‐FEC for a continuous multimedia stream transmission to multiple users and we examine how the amount of forward error correction redundancy can be adjusted under different packet loss conditions. For this purpose, we present a variety of realistic simulation scenarios for the application of AL‐FEC and furthermore we provide an in‐depth analysis of Raptor codes performance introducing valuable suggestions to achieve efficient use of Raptor codes. Copyright © 2012 John Wiley & Sons, Ltd.     

Enhancing the capacity of DS-CDMA system using hybrid spreading sequences

A new direct-sequence code-division multiple-access (DS-CDMA) system using hybrid spreading sequences in order to increase system capacity is proposed. This scheme permits accommodating more than N users, where N is the processing gain of the spreading sequences. Users are divided into two classes. The centerpiece idea is to synchronously assign N mutually orthogonal codes to class-1 users, and asynchronously assign quasi-orthogonal codes to class-2 users. The proposed architecture is realized through the DS-CDMA and multicode CDMA (MC-CDMA) techniques for class-1 and class-2 users, respectively, and the system capacity is considerably enhanced as compared with Sari et al.. The new approach still excels over Vanhaverbeke et al. when the number of class-1 users K/sub 1/ is large; but our desire is to expand system capacity. Compared with Sari et al. and Vanhaverbeke et al., the new design is able to support multirate applications, and is especially suitable for high-speed multimedia transmissions. Furthermore, the performance of the MC-CDMA system over an additive white Gaussian noise channel is evaluated for various primary codes and mutually orthogonal subcodes. It is shown that orthogonal Gold codes concatenated with Hadamard sequences yield the lowest bit-error rate when the signal-to-noise ratio lies between 0 and 30 dB.     

Performance Analysis of Variable-Weight Multilength Optical Codes for Wavelength–Time O-CDMA Multimedia Systems

To support multimedia services with different discrete bit-rate requirements, families of multilength optical codes, such as the carrier-hopping prime code (CHPC), extended CHPC, and multiwavelength optical orthogonal code, were recently constructed for wavelength-time optical code-division multiple-access (O-CDMA). In this paper, the performances of these multilength optical codes in a multimedia O-CDMA system with a variable-weight operation are analyzed. Our study shows that short-length codes generate stronger interference than long-length codes. This supports services prioritization in O-CDMA. Our study also shows that code weight is a more important factor than code length in determining code performance.