What are exclusive blockchains?

    Биткойн-блокчейн хорошо проявил себя в качестве децентрализованной электронной платежной платформы. Поэтому не удивительно, что успех биткойна привел к попыткам различных компаний адаптировать технологию для корпоративного применения. Например, эстонский LHV Bank внедрил систему платежей Cuber, основанную на окрашенных монетах (colored coins), организованных поверх биткойн-блокчейна.

    Однако разработчики корпоративных приложений быстро пришли к пониманию, что биткойн-блокчейн не может полностью удовлетворить их требования, по крайней мере, в краткосрочной перспективе. Это привело к появлению эксклюзивных блокчейнов (permissioned blockchain), о которых мы поговорим в сегодняшнем материале.

    / изображение Adam BaileyCC

    One of the obstacles to the direct adaptation of the public blockchain, which is Bitcoin, is its openness. In such a network, any participant can read data from the blockchain and write it, creating new transaction blocks. In other words, public blockchains are resistant to censorship. However, this feature ceases to be a virtue in the context of the internal work processes of a large company - in this case access control comes to the fore.

    Here, the so-called exclusive blockchains came to the rescue of companies. Exclusive blockchain is a blockchain in which transaction processing is carried out.a specific list of entities with established identities. Access to read data is also usually limited, although certain rights may extend beyond the circle of blockchain operators.

    For example, in a financial blockchain supported by several banks, data will be available to the regulator and law enforcement authorities; Bank customers will also be able to view their data. In addition, developers of third-party financial applications built on the basis of the blockchain with limited access to a specific set of information can be involved in this scheme.

    And global organizations are already exploring the possibilities of building their own exclusive blockchains. Three large Dutch banks ABN Amro, ING and Rabobank are exploring the use of blockchain for payment systems. And, for example, Citigroup built three blockchains and a domestic currency based on them in order to minimize risks when interacting with other banks.

    Features of exclusive blockchains

    Exclusive blockchains provide more control over the system on the part of the company. The bottom line is that such networks allow, for example, to quickly update functionality. Therefore, their use is most justified in institutions working with registries and accounting systems - exclusive blockchains form a more controlled environment compared to public blockchains.

    Another feature of exclusive blockchains is a transparent management structure. They also offer greater flexibility and adaptability compared to the open blockchain infrastructure. This allows exclusive blockchains to be used in solving very specific business problems - property rights management, journalism, and the electoral system.

    Many experts believe that they will solve many problems of financial organizations that are not able to solve, say, bitcoin. For example, compliance with the Life Insurance Mobility and Accountability Act (HIPAA) or Anti Money Laundering (AML).

    “Closed blockchains provide companies with an interesting opportunity to use untrustworthiness and transparency [of blockchains] in internal and inter-corporate scenarios,” says Dan Wasyluk, team leader at Syscoin.

    Creating blocks in an exclusive blockchain does not require proof of work . Instead, for consensus in exclusive blockchains, well-studied consensus algorithms with authenticated participants, for example, Practical Byzantine Fault Tolerance (PBFT), can be used . Another example is the block creation protocol used by BitShares. In such algorithms, each transaction processor has a pair of keys - private and public. The creators of the blocks are known and are identified by the digital signature of the block.

    Exclusive blockchain frameworks

    Exclusive blockchains are less global than public blockchains. When creating them, the developers do not set out to build a single infrastructure for any industry as a whole. For this reason, the development of exclusive blockchains is based on frameworks, while public blockchains are more like PaaS solutions . Roughly speaking, blockchain frameworks resemble DBMS in their tasks (the same DBMS can be substituted into the back-end of many sites), and public blockchains are web platforms like Twitter or Facebook (each platform is unique and has its own set of characteristics).

    Active development of frameworks for exclusive blockchains began recently - just a few years ago. Most of them have open source code (or it is planned to open it in the future), so anyone can start developing for exclusive blockchains. Of the most popular frameworks, there are:

    • Fabric A the IBM . IBM began developing its blockchain framework in 2015. In 2016, the IT giant became one of the founders of Hyperledger , a project under the wing of The Linux Foundation, aimed at developing enterprise standards for blockchains and distributed registries. The framework is written in Go and uses Docker containers to implement smart contracts.

    • Intel Sawtooth Lake . Intel approached the blockchain in terms of the Internet of Things. Among the features of Sawtooth Lake, we can distinguish the proof of elapsed time (PoET) consensus algorithm , which uses the SGX trusted computing module built into Intel's latest generations. Implemented in Python.

    • R3 Corda . Corda is the result of the work of the R3 consortium , which brings together the largest banks in the world. Unlike the other frameworks in question, Corda does not build blockchains, but distributed registries: Corda does not have the concept of blocks and large-scale data replication in general. Corda is written in Kotlin and supports smart contracts in any JVM-compatible language.

    • Enterprise Ethereum . Despite the fact that Ethereum is a public blockchain, its developers pay much attention to the use of product code to create exclusive blockchains. In early 2017, they announced the organization of the Enterprise Ethereum alliance, whose goal is to develop business-oriented functions (for example, the allocation of the consensus algorithm in a separate module).

    In addition to these solutions, there are many other frameworks: Chain , Monax , Symbiont , Axoni and so on. There are also a number of initiatives that bring Bitcoin's blockchain closer to the corporate environment, such as BloqEnterprise .

    Blockchain Snap

    Despite the fact that it is not necessary to use proof of work in exclusive blockchains, this protocol can still be connected. This approach simplifies the audit and further increases the level of security and control over the system for end users. In fact, proof of work translates trust in the blockchain from subjective, when trust in the system is equivalent to trust in the organization that controls it, into objective - here the level of trust is built on the basis of mathematical laws and the high economic cost of attacks on the system.

    Another way to “objectify” exclusive blockchains is to use a bindingto public blockchains. Blockchain anchoring is a technology according to which exclusive blockchain operators periodically send block hashes to be included in a supporting public blockchain in the format of transaction certificates.

    The closest analogy for blockchain binding is the publication of block headings in a print publication (for example, in a newspaper). Such a scheme was proposed by cryptographers in the early 1990s and is successfully used by some companies, for example Guardtime .

    The idea is the same in both cases: the binding tool (public blockchain or print) cannot be replaced retroactively due to the large circulation and high economic cost of the attack. Thus, the data recorded in the exclusive blockchain becomes undeniable, that is, they cannot be replaced, even if all the blockchain operators conspire with each other. The binding does not disclose any information about the exclusive blockchain (due to the use of hash functions) and at the same time fixes the current state of the blockchain as a whole (all blocks are connected in the same chain using the same hash functions).

    However, public blockchains have advantages over newspapers. They allow you to bind more often, flexibly configure its format (for example, you can record certain individual transactions of the exclusive blockchain), as well as conduct automatic checks. The information included in the linked blockchain can be verified by users of the exclusive blockchain. This ensures that the transaction history in the system remains unchanged (in fact, external proof of work is used for this).

    Binding an exclusive blockchain using a supporting public blockchain (for example, bitcoin)

    To attack a chain protected by binding to an open blockchain, an attacker needs to overcome the consensus mechanisms for both the exclusive blockchain and the supporting chain. Linking to blockchains themselves does not require a large amount of resources and does not create a critical dependence on the supporting blockchain - cooperation between exclusive blockchain operators and miners on the supporting blockchain is optional.

    Linking to blockchains solves the problem of diversifying the security of distributed registries and can be used in blockchains that do not use internal proof of work. At the same time, both approaches are not mutually exclusive and can be used simultaneously to increase the level of security.

    PS Related post: Another use of blockchains is smart contracts .

    Also popular now: