The Internet of Things (IoTs) enables coupling of digital and physical objects using worthy communication technologies and introduces a future vision where computing systems, users and objects cooperate for convenience and economic benefits. Such a vision requires seamless security, data privacy, authentication and robustness against attacks. These attributes can be introduced by blockchain, a distributed ledger that maintains an immutable log of network transactions. In this paper, we present a comprehensive review on how to remodel blockchain to the specific IoT needs in order to develop Blockchain based IoT (BIoT) applications and aim to shape a coherent picture of the current state-of-the-art efforts in this direction. After describing the basic characteristics and requirements of IoT, evolution of blockchain is presented. In this regard, we start with the fundamental working principles of blockchain and how such systems achieve auditability, security and decentralization. Further, we describe the most relevant BIoT applications, its architecture design and security aspects. From there, we build our narrative on the centralized IoT challenges followed by recent advances towards solving them. Finally, some future directions are enumerated with the aim to guide future BIoT researchers on challenges that needs to be considered ahead of deploying the next generation of BIoT applications.

物联网（IoT）可以使用有价值的通信技术实现数字和物理对象的耦合，并引入了未来的愿景，即计算系统，用户和对象之间的协作将带来便利和经济利益。这样的愿景需要无缝的安全性，数据保密性，身份验证和抵御攻击的鲁棒性。这些属性可以由区块链引入，区块链是维护网络交易不变日志的分布式分类帐。在本文中，我们对如何将区块链改造为特定的IoT需求进行了全面的回顾，以开发基于区块链的IoT（BIoT）应用程序，并旨在塑造当前在此方面的最新努力的连贯图景方向。在描述了物联网的基本特征和要求之后，提出了区块链的发展。在这方面，我们从区块链的基本工作原理开始，以及此类系统如何实现可审计性，安全性和分散性。此外，我们描述了最相关的BIoT应用程序，其架构设计和安全性方面。从那里开始，我们以集中式物联网挑战为基础，接着是解决这些挑战的最新进展。最后，列举了一些未来的方向，目的是指导未来的BIoT研究人员应对在部署下一代BIoT应用程序之前需要考虑的挑战。我们以集中式IoT挑战为基础，接着介绍解决挑战的最新进展。最后，列举了一些未来的方向，目的是指导未来的BIoT研究人员应对在部署下一代BIoT应用程序之前需要考虑的挑战。我们以集中式IoT挑战为基础，接着介绍解决挑战的最新进展。最后，列举了一些未来的方向，目的是指导未来的BIoT研究人员应对在部署下一代BIoT应用程序之前需要考虑的挑战。