Covert QR codes: How to hide in the crowd

This paper investigates a novel approach of distributing a hidden message via public channels. The proposed approach employs visual subterfuge to conceal secret information within a QR code. Using a QR code reader, any individual can decode the public information contained in the QR code. However, only authorized users who have the necessary credentials will be able to obtain the secret message, which is encoded in the form of a secret QR code. We call this a Covert QR (CQR) code scheme. To embed the secret information, this approach exploits the error correction mechanism inherent in the QR code structure. By using QR codes to conceal information, the proposed scheme has the advantage of reducing the likelihood of attracting the attention of potential adversaries. In addition, the information in QR codes can be scanned and decoded through the visual channel. As such, the secret information can be distributed on printed media and is not restricted to an electronic form

ESSVCS: an enriched secret sharing visual cryptography

Visual Cryptography (VC) is a powerful technique that combines the notions of perfect ciphers and secret sharing in cryptography with that of raster graphics. A binary image can be divided into shares that are able to be stacked together so as to approximately recover the original image. VC is a unique technique in the sense that the encrypted message can be decrypted directly by the Human Visual System (HVS). The distinguishing characteristic of VC is the ability of secret restoration without the use of computation. However because of restrictions of the HVS, pixel expansion and alignment problems, a VC scheme perhaps can only be applied to share a small size of secret image. In this paper, we present an Enriched Secret Sharing Visual Cryptography Scheme (ESSVCS) to let the VC shares carry more secrets, the technique is to use cypher output of private-key systems as the input random numbers of VC scheme, meanwhile the encryption key could be shared, the shared keys could be associated with the VC shares. After this operation, VC scheme and secret sharing scheme are merged with the private-key system. Under this design, we implement a (k; t; n)-VC scheme. Compared to those existing schemes, our scheme could greatly enhance the ability of current VC schemes and could cope with pretty rich secrets

Selected Papers from the First International Symposium on Future ICT (Future-ICT 2019) in Conjunction with 4th International Symposium on Mobile Internet Security (MobiSec 2019)

The International Symposium on Future ICT (Future-ICT 2019) in conjunction with the 4th International Symposium on Mobile Internet Security (MobiSec 2019) was held on 17–19 October 2019 in Taichung, Taiwan. The symposium provided academic and industry professionals an opportunity to discuss the latest issues and progress in advancing smart applications based on future ICT and its relative security. The symposium aimed to publish high-quality papers strictly related to the various theories and practical applications concerning advanced smart applications, future ICT, and related communications and networks. It was expected that the symposium and its publications would be a trigger for further related research and technology improvements in this field

Encrypting More Information in Visual Cryptography Scheme

The visual cryptography scheme (VCS) is a scheme which encodes a secret image into several shares, and only qualified sets of shares can recover the secret image visually, other sets of shares cannot get any information about the content of the secret image. From the point of view of encrypting (carrying) the secret information, the traditional VCS is not an efficient method. The amount of the information that a VCS encrypts depends on the amount of secret pixels. And because of the restrictions of the human eyes and the pixel expansion and the alignment problem of the VCS, a VCS perhaps can only be used to encrypt a small secret image. VCS requires a random number generator to guide the generation of the shares. As we will show in this paper, the random input of VCS can ba seen as a subchannel which helps carrying more secret information. We propose a general method to increase the amount of secret information that a threshold VCS can encrypt by treating the pseudo-random inputs of the VCS as a subchannel, i.e. the Encrypting More Information Visual Cryptography Scheme (EMIVCS). We also study the bandwidth of the proposed EMIVCS. The disadvantage of the proposed scheme is that, the decoding process is computer aided. However, compared with other computer aided VCS, the proposed scheme is more efficient

Application and Theory of Multimedia Signal Processing Using Machine Learning or Advanced Methods

This Special Issue is a book composed by collecting documents published through peer review on the research of various advanced technologies related to applications and theories of signal processing for multimedia systems using ML or advanced methods. Multimedia signals include image, video, audio, character recognition and optimization of communication channels for networks. The specific contents included in this book are data hiding, encryption, object detection, image classification, and character recognition. Academics and colleagues who are interested in these topics will find it interesting to read

Design of data validation solutions using high density 2D colored codes and a (2,2) xor-based color interference visual cryptography scheme

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2018.A validação de dados nos sistemas de informação utiliza majoritariamente algoritmos criptográficos em sistemas que, geralmente, não utilizam materiais não eletrônicos como parte da infraestrutura do criptossistema. Nesse trabalho, foram desenvolvidos dois sistemas de armazenamento e recuperação de dados através da proposta de uma nova tecnologia de códigos de barra colorido bidimensional e de um novo esquema de criptografia visual. Os códigos de barras bidimensionais têm sido amplamente estudados, mas ainda continuam sem contar com um padrão que consiga transmitir alta quantidade de informação em pequenos espaços impressos. As aplicações desse modelo de transmissão tem como motivação a necessidade de armazenar (e recuperar) uma alta quantidade de informação em pequenas áreas impressas, como por exemplo, para utilização de dados criptográficos que sejam processados sem conexão e armazenados em pequenos espaços impressos, como os de caixas de remédios ou caixas de cigarros. O código de barras colorido 2D proposto nesse trabalho é chamado de High Density 2 Dimensional Code (HD2DC) e possui 8 diferentes tamanhos. O HD2DC permite a utilização de 5 ou 8 cores em cada tamanho e conta com o algoritmo de correção de erro Reed-Solomon com 3 diferentes níveis (10%, 20% e 30%). O HD2DC foi desenvolvido com o objetivo de ser um padrão de código de barras colorido 2D para operações de transmissão de grande quantidade de informações em pequenas ou médias áreas de impressão. Criptografia visual é uma técnica que cifra uma imagem secreta em duas ou mais imagens chave. A decodificação de qualquer esquema de criptografia visual depende do sistema visual humano e a maioria das propostas existentes consideram para a decodificação a utilização da sobreposição de duas ou mais lâminas físicas com n x n (n ≥ 2) pixels expandidos. O esquema de criptografia visual proposto nesse trabalho considera a utilização de duas imagens. A primeira é uma lâmina física feita por uma impressão colorida em Policloreto de Polivinila (PVC) transparente de 3 milímetros, enquanto que a segunda é uma imagem colorida apresentada na tela do visor de um smartphone. Ambas as imagens não geram expansão de pixels. A obtenção das melhores cores utilizadas nesse criptossistema foi realizada através de estudos físicos do comportamento da interferência de cor entre a tela do smartphone e a cor utilizada na impressão do PVC transparente. Essa nova proposta possui um alto nível de usabilidade para validação de dados em transações eletrônicas e conta com um custo muito baixo de implementação. Um sistema robusto de validação de dados é criado quando é combinada a criptografia visual proposta com o HD2DC. O HD2DC tem a capacidade de armazenar uma das imagens chave, no caso a que deve ser mostrada no visor do celular, essa arquitetura de codificação aumenta a percepção de segurança e explora a usabilidade do celular por meio da utilização da câmera e da tela como ferramentas para mostrar a imagem cifrada da criptografia visual.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Digital data validation generally requires that algorithms are ran into on cryptographic systems that, usually, do not use non-electronic devices as part of their information security infrastructure. This work presents two information storage and retrieval systems: a new colored two-dimensional barcode technology and a novel visual cryptography scheme. Two-dimensional barcodes have been a topic of research for several decades, but there is still no standard that stores and retrieves high amounts of data. Recently, new requirements have been imposed on applications that use 2D barcodes as a communication channel, such as the capability of storing information into a small printed area. This particular requirement is specially important for 2D barcodes that store cryptographic primitives to be processed off-line. This is the case of barcodes in products like cigarettes and medicines, which are used for data validation and product verification. The proposed 2D colored barcode is called High Density Two-Dimensional Code (HD2DC) and is currently one of the 2D barcodes with the highest data density. HD2DC can be generated in 8 different sizes, with 5 or 8 colors. To increase robustness, the system uses a Reed-Solomon error correction algorithm with 3 different levels: Low, Medium and High, which provide approximately 10%, 20% and 30% error correction, respectively. Visual cryptography (VC) is a technique that encodes the content of a secret image into two or more images, which are called shares. These shares are printed on transparencies and superimposed (requiring a good alignment) to reveal (visually) the original secret image, i.e. without requiring any computation. Current visual cryptography schemes use at least 2 shares (transparencies) as keys. With respect to the secret image size, most of these schemes produce a n x n (n ≥ 2) size expansion of the shares and the decoded image. The proposed Visual Cryptography scheme, on the other hand, uses two shares and does not require a size expansion. The first share is a colored film printed on a Polyvinyl Chloride (PVC) surface of 3 millimeters, while the second share is a colored image displayed on a smartphone or tablet. In this work, we performed a physical evaluation of the color interference properties of these two shares (the printed PVC transparency and the image displayed on the mobile device) to find the most adequate color space to be used in the proposed cryptosystem. We also propose a strong validation system combining our Xor-Based Visual Cryptography scheme with HD2DC. HD2DC has the capability of storing the share that is shown on the mobile device display. This encoding architecture enhances security perception and explores the mobile device usability, using its screen to display a Visual Cryptography share

Digital watermarking methods for data security and authentication

Philosophiae Doctor - PhDCryptology is the study of systems that typically originate from a consideration of the ideal circumstances under which secure information exchange is to take place. It involves the study of cryptographic and other processes that might be introduced for breaking the output of such systems - cryptanalysis. This includes the introduction of formal mathematical methods for the design of a cryptosystem and for estimating its theoretical level of securit

ATTACKS AND COUNTERMEASURES FOR WEBVIEW ON MOBILE SYSTEMS

ABSTRACT All the mainstream mobile operating systems provide a web container, called ``WebView\u27\u27. This Web-based interface can be included as part of the mobile application to retrieve and display web contents from remote servers. WebView not only provides the same functionalities as web browser, more importantly, it enables rich interactions between mobile apps and webpages loaded inside WebView. Through its APIs, WebView enables the two-way interaction. However, the design of WebView changes the landscape of the Web, especially from the security perspective. This dissertation conducts a comprehensive and systematic study of WebView\u27s impact on web security, with a particular focus on identifying its fundamental causes. This dissertation discovers multiple attacks on WebView, and proposes new protection models to enhance the security of WebView. The design principles of these models are also described as well as the prototype implementation in Android platform. Evaluations are used to demonstrate the effectiveness and performance of these protection models

Digital rights management for electronic documents

Ph.DDOCTOR OF PHILOSOPH