In this paper we propose right-angled Artin groups as a platform for secret sharing schemes based on the efficiency (linear time) of the word problem. Inspired by previous work of Grigoriev-Shpilrain in the context of graphs, we define two new problems: Subgroup Isomorphism Problem and Group Homomorphism Problem. Based on them, we also propose two new authentication schemes. For right-angled Artin groups, the Group Homomorphism and Graph Homomorphism problems are equivalent, and the later is known to be NP-complete. In the case of the Subgroup Isomorphism problem, we bring some results due to Bridson who shows there are right-angled Artin groups in which this problem is unsolvable.

The authenticity of the historical garden, as defined by the Florence Charter, is conducive to its broad interpretation. In the era of the present crisis of conservation values, the identification of criteria helpful in an objective assessment of the authenticity of both historical and historising forms of greenery is required.

On the example of the restoration’s solutions in the gardens at Wilanów and the condition of selected elements of the urban greenery in Warsaw, it is possible to verify the model of valorization of factors determining the vegetation’s authenticity proposed by the author of the article. This model also allows to emphasize the features determining the role of royal gardens in Wilanów in maintaining the historical horticultural values of modern Warsaw.

This paper addresses the problem of tampering detection and discusses methods used for authenticity analysis of digital audio recordings. Presented approach is based on frame offset measurement in audio files compressed and decoded by using perceptual audio coding algorithms which employ modified discrete cosine transform. The minimum values of total number of active MDCT coefficients occur for frame shifts equal to multiplications of applied window length. Any modification of audio file, including cutting off or pasting a part of audio recording causes a disturbance within this regularity. In this study the algorithm based on checking frame offset previously described in the literature is expanded by using each of four types of analysis windows commonly applied in the majority of MDCT based encoders. To enhance the robustness of the method additional histogram analysis is performed by detecting the presence of small value spectral components. Moreover, computation of maximum values of nonzero spectral coefficients is employed, which creates a gating function for the results obtained based on previous algorithm. This solution radically minimizes a number of false detections of forgeries. The influence of compression algorithms' parameters on detection of forgeries is presented by applying AAC and Ogg Vorbis encoders as examples. The effectiveness of tampering detection algorithms proposed in this paper is tested on a predefined music database and compared graphically using ROC-like curves.

The water’s edge is the most iconic and identifiable image related to the city of Durban and in seeking an ‘authenticity’ that typifies the built fabric of the city, the image that this place creates is arguably the answer. Since its formal establishment as a settlement in 1824, this edge has been a primary element in the urban fabric. Development of the space has been fairly incremental over the last two centuries, starting with colonial infl uenced built interventions, but much of what is there currently stems from the 1930’s onwards, leading to a Modernist and later Contemporary sense of place that is moderated by regionalist infl uences, lending itself to creating a somewhat contextually relevant image. This ‘international yet local’ sense of place is however under threat from the increasingly prominent ‘global’ image of a-contextual glass high-rise towers placed along a non-descript public realm typical of global capital interests that is a hallmark of the turnkey project trends by developers from the East currently sweeping the African continent.

Among rapid development of wireless communication, technology cryptography plays a major role in securing the personal information of the user. As such, many authentication schemes have been proposed to ensure secrecy of wireless communication but they fail to meet all the required security goals. The proposed signcryption scheme uses multi-factor authentication techniques such as user biometrics, smart card and passwords to provide utmost security of personal information. In general, wireless devices are susceptible to various attacks and resource constraint by their very nature. To overcome these challenges a lightweight cryptographic scheme called signcryption has evolved. Signcryption is a logical combination of encryption and digital signature in a single step. Thereby it provides necessary security features in less computational and communication time. The proposed research work outlines the weaknesses of the already existing Cao et al.’s authentication scheme, which is prone to biometric recognition error, offline password guessing attack, impersonation attack and replay attack. Furthermore, the proposed study provides an enhanced multi-factor authentication scheme using signcryption based on hyper elliptic curve cryptography and bio-hash function. Security of the proposed scheme is analyzed using Burrows-Abadi-Needham logic. This analysis reveals that the proposed scheme is computational and communication-efficient and satisfies all the needed security goals. Finally, an analysis of the study results has revealed that the proposed scheme protects against biometric recognition error, password guessing attack, impersonation attack, DoS attack and dictionary attack.