Public health websites are regarded as official references that citizens of any country rely on for domestic and individual health affairs. For people with disabilities, public health resources are often of greater importance; they additionally provide disability context-specific information. However, to leverage the benefits of such resources for the widest demographic groups, Web accessibility requirements should be met at an acceptable level (e.g., WCAG 2.0, Level AA). This study evaluates the accessibility of a number of public health websites from 25 countries. The choice of the selected websites is determined by the extent of the COVID-19 outbreak in the corresponding countries and their rank as of late April, 2020. Ultimately, this study aims at shedding light on the current situation of accessibility to health information and pinpointing the aspects where accessibility to information falls short in public health websites. Using different evaluation tools, the overall results show that the vast majority of public health websites, of a number of different countries, still have many critical accessibility barriers, especially with regards to the perception of information and operability of the interface items. The findings of this study suggest a need for major efforts toward ensuring accessible public health resources in most of the evaluated websites. As this pattern has repeatedly occurred in many relevant studies in different parts of the world, legislation along with educating Web developers regarding Web accessibility requirements and universal design principles become an urgent necessity.

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Many chaos-based hash functions have convoluted designs that are not based on proper design principles, complicating the verification of security claims. We address this problem by proposing a hash function based on a chaotic sponge construction and DNA sequence. DNA sequence is used to design state transition rules of a deterministic chaotic finite-state automata (DCFSA), a chaotic structure that enhances the chaoticity of digital chaotic maps. We use a DCFSA configuration consisting of four states associated with logistic maps. Analysis shows that the DCFSA configuration is efficient and has high chaotic complexity. Both DCFSA and DNA are used to design the sponge-based hash function. An input message is transformed into a DNA sequence and divided into fixed-length blocks. Each block is absorbed into a sponge structure via DNA-XOR. The sponge state is then updated with a new DNA sequence by iterating DCFSA as a compression function. Statistical evaluations indicate that the proposed hash function has near-ideal diffusion, confusion, collision resistance and distribution properties. The proposed hash can also extend the provably secure notions of the sponge construction, specifically the indifferentiability from random oracles. Furthermore, the hash function has a high level of performance as compared to other chaosbased hash functions.INDEX TERMS Chaotic map DNA data integrity finite state automata hash function security

The COVID-19 pandemic increases the reliance on video conferencing applications for learning. Accessible video conferencing applications with good learning features can help people with visual impairment when they participate in online classes. This paper investigates the accessibility limitations and the available learning features of the top two current video conferencing applications, namely Zoom and MS Teams. A task-based expert review and a blind user evaluation are conducted using Web Content Accessibility Guidelines 2.1. In addition, the study identifies the application with the better learning features based on Universal Design for Learning guidelines. A set of recommendations are outlined for developing better inclusive video conferencing applications for people with visual impairment. The presented ideas can be applied to enhance the learning experience of people with visual impairment.

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