Biblio

Blockchain is seen as a promising technology to provide reliable and secure services due to its decentralized characteristic. However, because of the limited throughput, current blockchain platforms can not meet the transaction demand in practical use. Though researchers proposed many new solutions, they suffered either decentralization or security issues. In this paper, using Directed Acyclic Graph (DAG) structure, we improve the linear structure of traditional blockchain protocol. In the new structure, blocks are organized in levels and width, which will generate into a compacted DAG structure (CoDAG). To make CoDAG more efficient and secure, we design algorithms and protocols to place the new-generated blocks appropriately. Compared with traditional blockchain protocols, CoDAG improves the security and transaction verification time, and enjoys the consistency and liveness properties of blockchain. Taking adversary parties into consideration, two possible attack strategies are presented in this paper, and we further prove that CoDAG is a secure and robust protocol to resist them. The experimental results show that CoDAG can achieve 394 transactions per second, which is 56 times of Bitcoin's throughput and 26 times of Ethereum's.

Much recent work focuses on finding bugs and security vulnerabilities in smart contracts written in existing languages. Although this approach may be helpful, it does not address flaws in the underlying programming language, which can facilitate writing buggy code in the first place. We advocate a re-thinking of the blockchain software engineering tool set, starting with the programming language in which smart contracts are written. In this paper, we propose and justify requirements for a new generation of blockchain software development tools. New tools should (1) consider users' needs as a primary concern; (2) seek to facilitate safe development by detecting relevant classes of serious bugs at compile time; (3) as much as possible, be blockchain-agnostic, given the wide variety of different blockchain platforms available, and leverage the properties that are common among blockchain environments to improve safety and developer effectiveness.

The Blockchain is an emerging paradigm that could solve security and trust issues for Internet of Things (IoT) platforms. We recently introduced in an IETF draft (“Blockchain Transaction Protocol for Constraint Nodes”) the BIoT paradigm, whose main idea is to insert sensor data in blockchain transactions. Because objects are not logically connected to blockchain platforms, controller entities forward all information needed for transaction forgery. Never less in order to generate cryptographic signatures, object needs some trusted computing resources. In previous papers we proposed the Four-Quater Architecture integrating general purpose unit (GPU), radio SoC, sensors/actuators and secure elements including TLS/DTLS stacks. These secure microcontrollers also manage crypto libraries required for blockchain operation. The BIoT concept has four main benefits: publication/duplication of sensors data in public and distributed ledgers, time stamping by the blockchain infrastructure, data authentication, and non repudiation.