Digital images can be captured or generated by a variety of sources including digital cameras and scanners. In many cases it is important to be able to determine the source of a digital image. This paper presents methods for authenticating images that have been acquired using flatbed desktop scanners. The method is based on using the pattern noise of the imaging sensor as a fingerprint for the scanner, similar to methods that have been reported for identifying digital cameras. To identify the source scanner of an image a reference pattern is estimated for each scanner and is treated as a unique fingerprint of the scanner. An anisotropic local polynomial estimator is used for obtaining the reference patterns. To further improve the classification accuracy a feature vector based approach using an SVM classifier is used to classify the pattern noise. This feature vector based approach is shown to achieve a high classification accuracy.

This paper describes methods for forensic characterization of physical devices. This is important in verifying the trust and authenticity of data and the device that created it. Current forensic identification techniques for digital cameras, printers, and RF devices are presented. It is also shown how these techniques can fit into a general forensic characterization framework, which can be generalized for use with other devices.

A robust, invisible watermarking scheme is proposed for digital images, where the watermark is embedded using the block-based lapped orthogonal transform (LOT). The embedding process follows a spread spectrum watermarking approach. In contrast to the use of transforms such as discrete cosine transform, our LOT watermarking scheme allows larger watermark embedding energy while maintaining the same level of subjective invisibility. In particular, the use of LOT reduces block artifacts caused by the insertion of the watermark in a block-by-block manner, hence obtaining a better balance between invisibility and robustness. Moreover, we use a human visual system (HVS) model to adaptively adjust the energy of the watermark during embedding. In our HVS model, each block is categorized into one of four classes (texture, fine-texture, edge, and plain-area) by using a feature known as the texture masking energy. Blocks with edges are also classified according to the edge direction. The block classification is used to adjust the watermark embedding parameters for each block.

Future generations of in-vehicle Intelligent Transportation Systems (ITS) will network nearby vehicles for enhanced safety and efficiency.  Initially, these intelligent vehicles will utilize wireless communication to extend the perception horizon for individual drivers through warning messages of roadway hazards, including obstacles in the roadway, accidents, and hard-braking incidents.  Ultimately, this communication will become a vital part of automated highway systems including cooperative driving and coordinated collision avoidance.  For efficiency and cost reasons, the wireless communication is likely to be done directly between vehicles.  However, direct inter-  vehicle communication (IVC) presents unique security and scalability issues that must be addressed before these systems can be realized. 
  This dissertation describes a Communication Architecture for Reliable Adaptive Vehicular Ad hoc Networks (CARAVAN) to address these issues.  CARAVAN consists of IVC-specific parameterization for the physical layer, as well as protocols for the link and the network layers of the architecture.  In the development of CARAVAN, this dissertation makes the following contributions:  1. A study of the characteristics and requirements of the IVC network, elicited through analytical and simulation studies of the network.  2. A description of the services needed to support the distribution of the secret spreading codes and the additional scalability requirements that arise from the use of spread spectrum, in order to use spread spectrum to provide protection against Denial of Service attacks.  3. A methodology to balance the tradeoffs between radio range, spatial reuse, and multi-hop message delivery.  4. A novel mapping function, which maps discrete sections of roadway to timeslots allocated to vehicles that allows for significantly lower latencies for multi-hop transmissions.  5. Novel assignment rules, which specify the timeslots a vehicle is authorized to use,  that allow for significantly more efficient use of the allocated spectrum.  6. Assignment rules designed to automatically adapt the timeslot allocation to varying densities of vehicle traffic.  7. Forwarding rules at the network layer, including acknowledgement processing,  for the delivery of a-periodic messages to all nodes in the zone-of-relevance.  8. A network layer that leverages the benefits of varying radio ranges to reduce the latency in multi-hop message delivery. 
  Through simulation and analysis, the CARAVAN architecture is shown to present significant and measurable improvement over current IVC architecture proposals.

Despite the increase in email and other forms of digital communication, the use of printed documents continues to increase every year. Many types of printed documents need to be “secure” or traceable to the printer that was used to print them. Examples of these include identity documents (e.g. passports) and documents used to commit a crime. Traditional protection methods such as special inks, security threads, or holograms, can be cost prohibitive. The goals of our work are to securely print and trace documents on low cost consumer printers such as inkjet and electrophotographic (laser) printers. We will accomplish this through the use of intrinsic and extrinsic features obtained from modelling the printing process. Specically we show that the banding artifact in the EP print process can be viewed as an intrinsic feature of the printer used to identify both the model and make of the device. Methods for measuring and extracting the banding signals from documents are presented. The use of banding as an extrinsic feature is also explored.

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    Printer identication based on a printed document has many desirable forensic applications. In the electropho- tographic process (EP) quasiperiodic banding artifacts can be used as an effective intrinsic signature. However, in text only document analysis, the absence of large midtone ar- eas makes it difcult to capture suitable signals for banding detection. Frequency domain analysis based on the pro- jection signals of individual characters does not provide enough resolution for proper printer identication. Ad- vanced pattern recognition techniques and knowledge about the print mechanism can help us to device an appropriate method to detect these signatures. We can get reliable in- trinsic signatures from multiple projections to build a clas- sier to identify the printer. Projections from individual characters can be viewed as a high dimensional data set. In order to create a highly effective pattern recognition tool, this high dimensional projection data has to be repre- sented in a low dimensional space. The dimension reduc- tion can be performed by some well known pattern recog- nition techniques. Then a classier can be built based on the reduced dimension data set. A popular choice is the Gaussian Mixture Model where each printer can be rep- resented by a Gaussian distribution. The distributions of all the printers help us to determine the mixing coefcient for the projection from an unknown printer. Finally, the decision making algorithm can vote for the correct printer. In this paper we will describe different classication algo- rithms to identify an unknown printer. We will present the experiments based on several different EP printers in our printer bank. The classication results based on different classiers will be compared .

    Banding is one of the image artifacts for electrophotographic (EP) printers. Due to its origin within the EP process, it can also be viewed as an intrinsic signature of the specific printer. Modulating the EP process to generate banding signals that are below the human visual threshold but can be detected by effective detection approach can further extend the signature capacity. This deliberate banding signal can be viewed as extrinsic signature of a printer. Since modulating the printing process provides significant barrier of entry, it is effective in limiting the attack possibilities and can be an effective method to embed needed information regarding the document and the device it was printed on to provide unprecedented forensic information. One of the key issues with embedding extrinsic signature is the information should not be detectable by the human observer. However, the signature needs to be detectable by a suitable detection algorithm. In this paper, we will propose one method to modulate the exposure of the EP process to embed controlled quasi-periodic signature into a document. Based on the system level modeling and experimental verification of the EP process, machine detectable signatures that are below the human visual threshold can be embedded into a printed document without any perceivable degradation in image quality. Preliminary experiment results confirm our hypothesis that with properly designed control techniques, effective extrinsic signatures can be embedded into a document.

In today’s digital world securing dierent forms of content is very important in terms of protecting copyright and verifying authenticity. Many techniques have been developed to protect audio, video, digital documents, images, and programs (executable code). One example is watermarking of digital audio and images. We believe that a similar type of protection for printed documents is very important. The goals of our work are to securely print and trace documents on low cost consumer printers such as inkjet and electrophotographic (laser) printers. We will accomplish this through the use of intrinsic and extrinsic features obtained from modelling the printing process. In this paper we describe the use of image texture analysis to identify the printer used to print a document. In particular we will describe a set of features that can be used to provide forensic information about a document. We will demonstrate our methods using 10 EP printers.

In forensic applications, identification of the source of a printed document can be very critical. However, this task is very challenging, because there are a variety of factors, such as the media type, the age of the printer, and the amount of colorant left in the cartridge that can affect the characteristics of a printed document. For inkjet printers, the availability of different print modes, and the use of variety of ink types adds even more complexity to this process. In this paper, we investigate different texture features of the characters printed by inkjet printers for classification based on text-only documents. We check the in model stability of these features by using a cost function. Finally, we perform stepwise discriminant analysis to reduce the feature set.

Printer identification based on a printed document can provide forensic information to protect copyright and verify authenticity. In addition to intrinsic features (intrinsic signatures) of the printer, modulating the printing process to embed specific signature (extrinsic signatures) will further extend the encoding capacity. Some features generated by modulating EP process such like raggedness of the edge in the text, can be designed and utilized to help develop the extrinsic signature. By increasing the level of modulation, which increase reliability of detection and thus capacity, we can drive the extrinsic signature to a point without perceptual degradation of the image quality. In this paper, we will investigate embedding extrinsic signature in text documents using laser intensity as a signal modulation source and develop extrinsic signatures using both frequency as well as amplitude modulation. Preliminary experimental results showed that it is feasible to embed detectable extrinsic signatures in text characters without degrading perceptual text quality.

In today’s digital world securing different forms of content is very important in terms of protecting copyright and verifying authenticity. We have pre- viously described the use of image texture analy- sis to identify the printer used to print a docu- ment. In particular we described a set of features that can be used to provide forensic information describing a document. In this paper we will in- troduce a printer identification process that uses a support vector machine classifier. We will also examine the effect of font size, font type, paper type, and “printer age”.

HE, QINGFENG. Requirements-Based Access Control Analysis and Policy Specification. (Under the direction of Dr. Ana (Annie) I. Antón.)  Access control is a mechanism for achieving confidentiality and integrity in software systems.  Access control policies (ACPs) define how access is managed and the high-level rules of who can access what information under certain conditions. Traditionally, access control policies have been specified in an ad-hoc manner, leaving systems vulnerable to security breaches. ACP specification is often isolated from requirements analysis, resulting in policies that are not in compliance with system requirements. This dissertation introduces the Requirements-based Access Control Analysis and Policy Specification (ReCAPS) method for deriving access control policies from various sources, including software requirements specifications (SRS), software designs, and high-level security/privacy policies. The ReCAPS method is essentially an analysis method supported by a set of heuristics and a software tool: the Security and Privacy Requirements Analysis Tool (SPRAT). The method was developed in two formative case studies and validated in two summative case studies. All four case studies involved operational systems,  and ReCAPS evolved as a result of the lessons learned from applying the method to these case studies. Further validation of the method was performed via an empirical study to evaluate the usefulness and effectiveness of the approach.  Results from these evaluations indicate that the process and heuristics provided by the ReCAPS method are useful for specifying database-level and application-level ACPs. Additionally, ReCAPS integrates policy specification into software development, thus providing a basic framework for ensuring compliance between different levels of policies, system requirements and software design. The method also improves the quality of requirements specifications and system designs by clarifying ambiguities and resolving conflicts across these artifacts.