An Overview on Image Forensics

The aim of this survey is to provide a comprehensive overview of the state of the art in the area of image forensics. These techniques have been designed to identify the source of a digital image or to determine whether the content is authentic or modified, without the knowledge of any prior information about the image under analysis (and thus are defined as passive). All these tools work by detecting the presence, the absence, or the incongruence of some traces intrinsically tied to the digital image by the acquisition device and by any other operation after its creation. The paper has been organized by classifying the tools according to the position in the history of the digital image in which the relative footprint is left: acquisition-based methods, coding-based methods, and editing-based schemes

TTP-free Asymmetric Fingerprinting based on Client Side Embedding

In this paper, we propose a solution for implementing an asymmetric fingerprinting protocol within a client-side embedding distribution framework. The scheme is based on two novel client-side embedding techniques that are able to reliably transmit a binary fingerprint. The first one relies on standard spread-spectrum like client-side embedding, while the second one is based on an innovative client-side informed embedding technique. The proposed techniques enable secure distribution of personalized decryption keys containing the Buyer's fingerprint by means of existing asymmetric protocols, without using a trusted third party. Simulation results show that the fingerprint can be reliably recovered by using either non-blind decoding with standard embedding or blind decoding with informed embedding, and in both cases it is robust with respect to common attacks. To the best of our knowledge, the proposed scheme is the first solution addressing asymmetric fingerprinting within a clientside framework, representing a valid solution to both customer's rights and scalability issues in multimedia content distributio

Secure Watermarking for Multimedia Content Protection: A Review of its Benefits and Open Issues

Distribution channels such as digital music downloads, video-on-demand, multimedia social networks, pose new challenges to the design of content protection measures aimed at preventing copyright violations. Digital watermarking has been proposed as a possible brick of such protection systems, providing a means to embed a unique code, as a fingerprint, into each copy of the distributed content. However, application of watermarking for multimedia content protection in realistic scenarios poses several security issues. Secure signal processing, by which name we indicate a set of techniques able to process sensitive signals that have been obfuscated either by encryption or by other privacy-preserving primitives, may offer valuable solutions to the aforementioned issues. More specifically, the adoption of efficient methods for watermark embedding or detection on data that have been secured in some way, which we name in short secure watermarking, provides an elegant way to solve the security concerns of fingerprinting applications. The aim of this contribution is to illustrate recent results regarding secure watermarking to the signal processing community, highlighting both benefits and still open issues. Some of the most interesting challenges in this area, as well as new research directions, will also be discussed

Reconsolidation of appetitive instrumental memory and the metaplastic effects of NMDA receptors blockade in rats

Obesity is one of the leading cause of death in world\u2019s population, due to the comorbidity with pathologies like cardiovascular or mental disorders. Deviating from its role as a primary need, obese and overweight people tend to use food as a source of pleasure or to relieve from anxiety, typical of addiction to drugs. Thus, due to the commonality with drug abuse, like the impulsive-to-compulsive progression or the neurotransmitters release, overconsumption of high palatable food has been described as a form of addiction. As initially done for fear and drug maladaptive memories, food addiction has been investigated with memory reconsolidation studies. Reconsolidation theory stated that after stabilization, memory can return into a vulnerable state with re-exposure to stimuli previously associated to the initial learning and, once reactivated and destabilized, it needs reconsolidation to be restabilized. During the vulnerable phase, memory can strengthened or disrupted, and memory disruption could prevent relapse. The processes of memory destabilization and restabilization have been shown to depend on glutamatergic signaling. Moreover, glutamate receptor activity has been proposed as modulated by metaplasticity, a novel concept according to which neural stimulation could influence future synaptic activity even after disappearing of the acute effect. Thus, the goals of the present project was to investigate i) whether sucrose instrumental memory can undergo reconsolidation and ii) if it is possible to block reconsolidation with the NMDARs antagonist MK-801 given under a metaplasticity protocol. After 10 days of training to sucrose self-administration, rats were fasted for 14 days and finally treated with vehicle or MK-801 24 hours before retrieval. Then, rats were exposed to memory retrieval (Ret) or no-retrieval (No-Ret) and, 24 hours later, a reinstatement test evaluated sucrose seeking behaviour. Separate groups of rats were sacrificed 2 hours after memory Ret/No-Ret for the molecular analyses of Zif268, rpS6P and glutamate receptors levels in memory and reward key brain areas: nucleus accumbens (NAc) and amygdala (Amy). Results showed that sucrose instrumental memory undergo reconsolidation, as indicated by the increase of Zif268 and rpS6P in NAc and Amy. These results were further supported by the increased level of GluN2B (destabilization marker) and GluA1 (reactivation marker) in Amy, leading us to propose the Zif268/rpS6P two-component molecular assay as a valid and reliable method for the assessment of instrumental memory reactivation and reconsolidation. Furthermore, we demonstrated that the metaplastic treatment with MK-801 significantly decreased instrumental responding at the behavioural test only when administrated 24 hours before Ret, and this inhibition was associated to a significant decrease of Zif268 in NAc shell and of rpS6P in central Amy. Moreover, acute MK-801 significantly increased GluA1, GluN2B and mGluR5 in NAc and GluN2B in Amy. Here we demonstrated that NMDARs blockade affected sucrose instrumental memory, hypothesizing that the metaplasticity effect of MK-801 could have induced a switch from reconsolidation-to-extinction occurrence. However, it remains to be clarified the molecular mechanisms allowing for instrumental responding inhibition even at time MK-801 has been completely eliminated, and whether this inhibition is long-lasting, making it a possible therapeutic treatment for relapse on food addiction

Anticollusion solutions for asymmetric fingerprinting protocols based on client side embedding

In this paper, we propose two different solutions for making a recently proposed asymmetric fingerprinting protocol based on client-side embedding robust to collusion attacks. The first solution is based on projecting a client-owned random fingerprint, securely obtained through existing cryptographic protocols, using for each client a different random matrix generated by the server. The second solution consists in assigning to each client a Tardos code, which can be done using existing asymmetric protocols, and modulating such codes using a specially designed random matrix. Suitable accusation strategies are proposed for both solutions, and their performance under the averaging attack followed by the addition of Gaussian noise is analytically derived. Experimental results show that the analytical model accurately predicts the performance of a realistic system. Moreover, the results also show that the solution based on independent random projections outperforms the solution based on Tardos codes, for different choices of parameters and under different attack models