Steganography has evolved into various forms and remains an effective way to hide sensitive information. Network Steganography, also known as "Covert Channels," is popular in fields such as terrorism and security. As a result, the scientific community created a specific taxonomy to categorize it, and developed several techniques and tools to conceal communication between the parties. In this paper, we have curated a list of available software tools that can be used to create a covert channel at layers 2 to 4 of the ISO/OSI model and related to the HTTP protocol.

International audience

Hybrid Casper is the new Ethereum blockchain protocol that uses both Proof of Work and Proof of Stake to reach a consensus between nodes. Here, we analyze the protocol using PRISM+ , an extension of the probabilistic model checker PRISM with primitives for expressing blockchain data types. First, we extend PRISM+ to include data types and operations for modeling and analyzing Proof of Stake based consensus protocols. Then, we model Hybrid Casper in PRISM+ as a parallel composition of stochastic processes, thus precisely describing the behavior of the protocol and highlighting its corner cases. PRISM+ is therefore used to rapidly and automatically analyze the resilience of Hybrid Casper when tuning, up or down, several basic parameters of the protocol, such as the rates of creating blocks, and the strategies for determining penalties. Finally, we study the robustness of Hybrid Casper to two well-known attacks: the Eclipse attack and the majority attack.

Although Bitcoin is a relatively new subject in Economics, contributions in this topic are growing very fast. Several papers evidenced a bubble behaviour in exchange rates between Bitcoin and traditional currencies. In this paper we explore and give validation to such conjecture, proving also that the bubble effect is due to confidence in Bitcoin future values. This means that Bitcoin price/exchange rate is influenced both by future and past events, but that the bubble behaviour is strictly connected to trust on the future of the Bitcoin system.