DeepMasterPrints: Generating MasterPrints for Dictionary Attacks via Latent Variable Evolution

Recent research has demonstrated the vulnerability of fingerprint recognition systems to dictionary attacks based on MasterPrints. MasterPrints are real or synthetic fingerprints that can fortuitously match with a large number of fingerprints thereby undermining the security afforded by fingerprint systems. Previous work by Roy et al. generated synthetic MasterPrints at the feature-level. In this work we generate complete image-level MasterPrints known as DeepMasterPrints, whose attack accuracy is found to be much superior than that of previous methods. The proposed method, referred to as Latent Variable Evolution, is based on training a Generative Adversarial Network on a set of real fingerprint images. Stochastic search in the form of the Covariance Matrix Adaptation Evolution Strategy is then used to search for latent input variables to the generator network that can maximize the number of impostor matches as assessed by a fingerprint recognizer. Experiments convey the efficacy of the proposed method in generating DeepMasterPrints. The underlying method is likely to have broad applications in fingerprint security as well as fingerprint synthesis.Comment: 8 pages; added new verification systems and diagrams. Accepted to conference Biometrics: Theory, Applications, and Systems 201

Novel solid-state emissive polymers and polymeric blends from a T-Shaped benzodifuran scaffold: A comparative study

Two novel polyimines were synthesized from a benzodifuran based diamino monomer and two dialdehydes bearing bulky groups and a flexible spacer. The polymers display tuned luminescence performance according to the presence of half-salen groups. The effect of the intramolecular bond on the emission properties were examined. Two model compounds, replicating the same emissive Schiff base cores, were synthetized. From the models, dye-doped blends in the fluorophore/matrix ratio, resembling the polymers, were produced. Amorphous thin films of the covalent polymers and the polymeric blends were obtained by spin-coating technique. The Photoluminescent (PL) response of the different macromolecular systems were qualitatively and quantitatively examined and compared

Evaluation of fingerprint development reagents for biological stain detection

Some latent fingerprint development techniques rely on the reaction with amino acids within the fingerprint and then either change in color or fluoresce to help visualize this fingerprint. Amino acids are the building blocks of proteins and are present in all biological fluid. Thus, these developers should be able to also locate biological stains. In a previous study, ninhydrin was shown to be able to locate biological stains. Two more latent fingerprint developers are introduced as possible universal biological stain detectors: 1,8-diazafluoren-9-one (DFO), and 1,2-indanedione (1,2-IND). Five biological stains were used to test these chemicals: 1:500 diluted blood, saliva, semen, sweat, and urine. A new heating method was also introduced for a more portable application. The hair dryer heating method was optimized for the three chemicals with two traditional oven heating methods: the oven setting at 70oC and the oven setting at 100oC. These chemicals were also examined for their effectiveness on aged samples. Samples aged for three different time intervals were used: 4 weeks, 8 weeks, and 16 weeks. The hair dryer heating method was found to be viable for all three chemicals for each of the biological stains except the 1:500 diluted blood. With the application of the hair dryer for less than 3 minutes, most stains were visible for all three chemicals. 1,2-IND gave slightly different color changes for sweat and the other biological stains. This property can possibly be used to guide subsequent specific body fluids testing. All three chemicals lost their effectiveness as the stain became older. One-month-old stains still gave similar results as fresh stains, but after 2 months, the color became fainter and was barely visible after 4 months. The next stage of this study applied these chemicals as a guide for wearer DNA extraction from worn clothing. Sampling for wearer DNA has mostly been an educated guess with little guidance as to where an abundance of DNA is located. Fingerprint developers can react with amino acids, and cells contain abundant amino acids. Thus, these chemicals may react more to areas with abundant cells. Wearer DNA was extracted from collars of donated shirts before and after the chemical applications to determine the effectiveness of these chemicals as DNA detectors. Of the three collars tested, ninhydrin reacted completely with two of the collars, making any distinction between areas with abundant DNA and areas with no DNA difficult. In addition, the quantitation data of the ninhydrin samples showed no advantage in using ninhydrin as a wearer DNA locator. DFO was shown to have some detrimental effects on the DNA or the DNA extraction and quantitation process. The quantitation data for DFO also showed no advantage in using DFO as a wearer DNA locator. 1,2-IND showed promising results and was the most likely candidate as a wearer DNA locator. All areas that reacted with 1,2-IND produced at least one sample having higher than 0.01 nanograms per microliter of DNA and would be considered viable for DNA profiling

Structure analysis of biologically important prokaryotic glycopolymers

Of the many post-translational modifications organisms can undertake, glycosylation is the most prevalent and the most diverse. The research in this thesis focuses on the structural characterisation of glycosylation in two classes of glycopolymer (lipopolysaccharide (LPS) and glycoprotein) in two domains of life (bacteria and archaea). The common theme linking these subprojects is the development and application of high sensitivity analytical techniques, primarily mass spectrometry (MS), for studying prokaryotic glycosylation. Many prokaryotes produce glycan arrangements with extraordinary variety in composition and structure. A further challenge is posed by additional functionalities such as lipids whose characterisation is not always straightforward. Glycosylation in prokaryotes has a variety of different biological functions, including their important roles in the mediation of interactions between pathogens and hosts. Thus enhanced knowledge of bacterial glycosylation may be of therapeutic value, whilst a better understanding of archaeal protein glycosylation will provide further targets for industrial applications, as well as insight into this post- translational modification across evolution and protein processing under extreme conditions. The first sub-project focused on the S-layer glycoprotein of the halophilic archeaon Haloferax volcanii, which has been reported to be modified by both glycans and lipids. Glycoproteomic and associated MS technologies were employed to characterise the N- and O-linked glycosylation and to explore putative lipid modifications. Approximately 90% of the S-layer was mapped and N-glycans were identified at all the mapped consensus sites, decorated with a pentasaccharide consisting of two hexoses, two hexuronic acids and a methylated hexuronic acid. The O-glycans are homogeneously identified as a disaccharide consisting of galactose and glucose. Unexpectedly it was found that membrane-derived lipids were present in the S- layer samples despite extensive purification, calling into question the predicted presence of covalently linked lipid. The H. volcanii N-glycosylation is mediated by the products of the agl gene cluster and the functional characterisation of members of the agl gene cluster was investigated by MS analysis of agl-mutant strains of the S-layer. Burkholderia pseudomallei is the causative agent of melioidosis, a serious and often fatal disease in humans which is endemic in South-East Asia and other equatorial regions. Its LPS is vital for serum resistance and the O-antigen repeat structures are of interest as vaccine targets. B. pseudomallei is reported to produce several polysaccharides, amongst which the already characterised ‘typical’ O-antigen of K96243 represents 97% of the strains. The serologically distinct ‘atypical’ strain 576 produces a different LPS, whose characterisation is the subject of this research project. MS strategies coupled with various hydrolytic and chemical derivatisation methodologies were employed to define the composition and potential sequences of the O-antigen repeat unit. These MS strategies were complemented by a novel NMR technique involving embedding of the LPS into micelles. Taken together the MS and NMR data have revealed a highly unusual O-antigen structure for atypical LPS which is remarkably different from the typical O-antigen. The development of structural analysis tools in MS and NMR applicable to the illustrated types of glycosylation in these prokaryotes will give a more consistent approach to sugar characterisation and their modifications thus providing more informative results for pathogenicity and immunological studies as well as pathway comparisons.Open Acces

Do GANs leave artificial fingerprints?

In the last few years, generative adversarial networks (GAN) have shown tremendous potential for a number of applications in computer vision and related fields. With the current pace of progress, it is a sure bet they will soon be able to generate high-quality images and videos, virtually indistinguishable from real ones. Unfortunately, realistic GAN-generated images pose serious threats to security, to begin with a possible flood of fake multimedia, and multimedia forensic countermeasures are in urgent need. In this work, we show that each GAN leaves its specific fingerprint in the images it generates, just like real-world cameras mark acquired images with traces of their photo-response non-uniformity pattern. Source identification experiments with several popular GANs show such fingerprints to represent a precious asset for forensic analyses