No abstract

No abstract

Today, with the development of processing technologies and improvement in cloud networks, a large number of photos are transferred in networks. The need to hide data and maintain security attracted the attention of researchers. In this paper, a reversible data hiding method based on the prediction error histogram shifting is proposed in order to increase the embedding capacity and maintains the visual quality of the image as well. To reach these goals, the original image is transformed into block-wise and for each block the prediction method is figured based on the proposed method to create prediction errors. According to our prediction method, in each block, 75% of the prediction error pixels can find the ability to embed information. The experimental results show a good acceptable embedding capacity as it is clear in a sample test image of an airplane. In this case, the embedding capacity of 206,270 bits and a Peak Signal-to-Noise Ratio (PSNR) of 50/99 have been reached. These results show the efficiency of our proposed method based on the embedding capacity and visual quality of the images. The outcomes of the proposed method reach better results than the main competitor methods.

In the recent research of vehicular ad-hoc networks (VANETs), new practical goals are pursued. They provide real-world communications between vehicles and make them reliable and easy-used. The VANETs have a fundamental role in reducing traffic accidents and improving traffic on the roads. Authentication in VANETs is a critical security service, and vehicles should be protected from breaking their personal information. Vehicles can be traced and investigated in the event of an accident or liability arising out of non-repudiation when the vehicle is faced with a rush of incoming messages. Hence, the roadside units' (RSUs) efficiency is reduced and causes delays in checking messages. This study presents an authentication framework using proxy vehicles for VANETs. Reducing the computational cost and proficiency increment are the features of the proposed method on the RSUs side. The proposed framework supports managing the revocation list. The Vehicle-to-Infrastructure (V2I) and Vehicle-to-Vehicle (V2V) authentication protocols are guaranteed and designed in this proposed framework, to show this, a merged V2I and V2V authentication is presented and embedded in the proposed framework. The designed protocol applies offline and online signatures to check messages and the revocation key to prevent malicious messages from being sent, and the time limit to use the network. The analysis shows that the suggested protocol is more feasible and reasonable for use in VANETs.

No abstract