Current Issue : October - December Volume : 2011 Issue Number : 1 Articles : 5 Articles
Extracting binary strings from real-valued biometric templates is a fundamental step in template compression and protection systems, such as fuzzy commitment, fuzzy extractor, secure sketch, and helper data systems. Quantization and coding is the straightforward way to extract binary representations from arbitrary real-valued biometric modalities. In this paper, we propose a pairwise adaptive phase quantization (APQ) method, together with a long-short (LS) pairing strategy, which aims to maximize the overall detection rate. Experimental results on the FVC2000 fingerprint and the FRGC face database show reasonably good verification performances....
Digital fingerprinting is a method to insert user's own ID into digital contents in order to identify illegal users who distribute unauthorized copies. One of the serious problems in a fingerprinting system is the collusion attack such that several users combine their copies of the same content to modify/delete the embedded fingerprints. In this paper, we propose a collusion-resistant fingerprinting scheme based on the CDMA technique. Our fingerprint sequences are orthogonal sequences of DCT basic vectors modulated by PN sequence. In order to increase the number of users, a hierarchical structure is produced by assigning a pair of the fingerprint sequences to a user. Under the assumption that the frequency components of detected sequences modulated by PN sequence follow Gaussian distribution, the design of thresholds and the weighting of parameters are studied to improve the performance. The robustness against collusion attack and the computational costs required for the detection are estimated in our simulation....
Watermarking payload is a topic in which the watermarking researchers have a great interest at present. Based on the constraint of ââ?¬Å?perceptual invisibility,ââ?¬Â this paper makes a study of the maximum watermarking payload of spatial domain image, which is related to not only embedding intensity, but also to factors such as the size of image, image roughness and visual sensitivity, and so forth. The correlation among the maximum payload and the embedding intensity and size of an image is theoretically deduced through the objective estimation indicator of the peak signal to the noise rate (PSNR) while the relationship model among watermarking payload and image roughness and visual sensitivity is deduced through effective experiments designed on the basis of subjective estimation indicators. Finally, taking all these relationship models into account, this paper proposes a watermarking payload estimation method and verifies its effectiveness through experiments....
Recently, arithmetic coding has attracted the attention of many scholars because of its high compression capability. Accordingly, this paper proposed a Joint Source-Cryptographic-Channel Coding (JSCC) based on Arithmetic Coding (AC). For this purpose, embedded error detection arithmetic coding, which is known as continuous error detection (CED), is used. In our proposed method, a random length of forbidden symbol which is produced with a key is used in each recursion. The dummy symbol is divided into two dummy symbols with a key and then is placed in random positions in order to provide security. Finally, in addition to producing secure codes, the suggested method reduced the added redundancy to half of the total redundancy added by CED. It has less complexity than cascades source, channel coding, and encryption while its key space in comparison to other joint methods has enlarged. Moreover, the coder provides a flexible switch between a standard compression model and a joint model....
An automatic video-object oriented steganographic system is proposed for biometrics authentication over error-prone networks. Initially, the host video object is automatically extracted through analysis of videoconference sequences. Next, the biometric pattern corresponding to the segmented video object is encrypted by a chaotic cipher module. Afterwards, the encrypted biometric signal is inserted to the most significant wavelet coefficients of the video object, using its qualified significant wavelet trees (QSWTs). QSWTs provide both invisibility and significant resistance against lossy transmission and compression, conditions that are typical in error prone networks. Finally, the inverse discrete wavelet transform (IDWT) is applied to provide the stego-object. Experimental results under various losses and JPEG compression ratios indicate the security, robustness, and efficiency of the proposed biometrics hiding system....
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