We present IPchain, a blockchain to store the allocations and delegations of IP addresses, with the aim of easing the deployment of secure interdomain routing systems. Interdomain routing security is of vital importance to the Internet since it prevents unwanted traffic redirections. IPchain makes use of blockchains' properties to provide flexible trust models and simplified management when compared to existing systems. In this paper we argue that Proof of Stake is a suitable consensus algorithm for IPchain due to the unique incentive structure of this use-case. We have implemented and evaluated IPchain's performance and scalability storing around 150k IP prefixes in a 1GB chain.
 Blockchains like Bitcoin and Namecoin and their respective P2P networks have seen significant adoption in the past few years and show promise as naming systems with no trusted parties. Users can register human meaningful names and securely associate data with them, and only the owner of the particular private keys that registered them can write or update the name-value pair. In theory, many decentralized systems can be built using these blockchain networks, such as new, decentralized versions of DNS and PKI. As the technology is relatively new and evolving rapidly, however, little production data or experience is available to guide design tradeoffs. In this paper, we describe our experiences operating a large deployment of a decentralized PKI service built on top of the Namecoin blockchain. We present various challenges pertaining to network reliability, throughput, and security that we needed to overcome while registering and updating over 33,000 entries and 200,000 transactions on the Namecoin blockchain. Further, we discuss how our experience informed the design of a new blockchain-based naming and storage system called Blockstack. We detail why we switched from the Namecoin network to the Bitcoin network for the new system, and present operational lessons from this migration. Blockstack is released as open source software and currently powers a production PKI system for 55,000 users. Recent interest about the blockchain technology brought questions about its application to other systems than the cryptocurrency one. In this paper we present blockchain and discuss key applications to network systems in the literature. Existing security mechanisms for managing the Internet infrastructural resources like IP addresses, AS numbers, BGP advertisements and DNS mappings rely on a Public Key Infrastructure (PKI) that can be potentially compromised by state actors and Advanced Persistent Threats (APTs). Ideally the Internet infrastructure needs a distributed and tamper-resistant resource management framework which cannot be subverted by any single entity. A secure, distributed ledger enables such a mechanism and the blockchain is the best known example of distributed ledgers. In this paper, we propose the use of a blockchain based mechanism to secure the Internet BGP and DNS infrastructure. While the blockchain has scaling issues to be overcome, the key advantages of such an approach include the elimination of any PKI-like root of trust, a verifiable and distributed transaction history log, multi-signature based authorizations for enhanced security, easy extensibility and scriptable programmability to secure new types of Internet resources and potential for a built in cryptocurrency. A tamper resistant DNS infrastructure also ensures that it is not possible for the application level PKI to spoof HTTPS traffic. User, content, and device names as a security primitive have been an attractive approach especially in the context of Information-Centric Networking (ICN) architectures. We leverage Hierarchical Identity Based Encryption (HIBE) to build (content) name-based security mechanisms used for securely distributing content. In contrast to similar approaches, in our system each user maintains his own Private Key Generator used for generating the master secret key and the public system parameters required by the HIBE algorithm. This way our system does not suffer from the key escrow problem, which is inherent in many similar solutions. In order to disseminate the system parameters of a content owner in a fully distributed way, we use blockchains, a distributed, community managed, global list of transactions. Motivated by the recent explosion of interest around blockchains, we examine whether they make a good fit for the Internet of Things (IoT) sector. Blockchains allow us to have a distributed peer-to-peer network where non-trusting members can interact with each other without a trusted intermediary, in a verifiable manner. We review how this mechanism works and also look into smart contracts—scripts that reside on the blockchain that allow for the automation of multi-step processes. We then move into the IoT domain, and describe how a blockchain-IoT combination: 1) facilitates the sharing of services and resources leading to the creation of a marketplace of services between devices and 2) allows us to automate in a cryptographically verifiable manner several existing, time-consuming workflows. We also point out certain issues that should be considered before the deployment of a blockchain network in an IoT setting: from transactional privacy to the expected value of the digitized assets traded on the network. Wherever applicable, we identify solutions and workarounds. Our conclusion is that the blockchain-IoT combination is powerful and can cause significant transformations across several industries, paving the way for new business models and novel, distributed applications.