Public blockchains allow communities around the world to openly and securely share information. However, the obvious disadvantage of this type of blockchain is that it can be compromised. The rules adopted and applied from the very beginning of the blockchain system cannot be changed long after their aceptance.
Private Blockchain. Unlike a public blockchain, private blockchains are those that are used only by trusted participants. General control over the network is in the hands of the system owners. Moreover, the rules of a private blockchain system can be changed depending on different levels of power, exposure, number of participants, authorization, and so on.
Private blockchains can operate independently of other processes or they can be combined with other blockchains. This use case is usually used by enterprises and organizations. Thus, the level of trust that is required among participants is higher in private chains than in public.
2. Select the platform on which the blockchain technology will be created
There are many solutions for creating blockchain platforms such as Ethereum, Hyperledger, Multichain, Open Ledger, Chain, Bitcoin Blockchain, Corda, etc. Some of them are still immature platforms. Thus, it is necessary to choose the most suitable platform for your desires based on your needs.
Ethereum platform is the most popular for creating blockchain projects. Due to the dynamism and responsiveness of the Ethereum community, as well as the richness of its documentation, the concept of the blockchain built on this platform means that the objects will be completely autonomous and belong only to themselves.
Hyperledger Fabric is the second by popularity platform.
Hyperledger Fabric is a relatively new platform for building a blockchain. Hyperledger Fabric has several distinctive features compared to other modern blockchain models; whether these characteristics are advantages or disadvantages often depends on the context.
Hyperledger Fabric is a software framework for developing applications and specialized blockchain-based business solutions.
One of the features of Hyperledger is the prinicipal rejection of creating your own cryptoactive assets. Hyperledger members develop projects especially as information technology.
Regardless of how the blockchain technology will be used, companies will either turn to their supplier partners for software development or work on technology development within the company.
It should be noted that regardless of whether the company makes the implementation of blockchain technology through an internal or external team, it is important that the company gain experience with blockchain technology, since the technology is new and complex for most companies.
For IT stores that want to implement a blockchain project, there is a very broad, though immature, ecosystem developing around blockchain technology. According to a recent report by 451 Research, there are nearly 300 Bitcoin and blockchain startups around the world working on developing technologies in the areas of financial, grocery, storage services, smart contracts(on Ethereum), social networks, supply chain management, identity management, retail and IoT. Most major IT manufacturers are actively working on the blockchain, in particular, IBM, which has allocated significant resources for the Hyperledger project for the Linux Foundation and Microsoft, which works with the R3 CEV banking industry consortium to enable testing of system chains using Microsoft Azure.
3. Create the first blockchain
To initialize a blockchain, you need to create the first block, then the blocks will be automatically created and structured. This unit must contain all the characteristics of the circuit. After that, the blocks will be available for all nodes (or users) of the network. To start creating a chain block, you need to create a JSON file. You need to specify several parameters: “nonce” (a normal cryptographic hash that generates a random value), “time tag” (the test time between two consecutive blocks), etc. After filling in the JSON file, everything depends on the Geth client. Create a folder containing a chain (chaindata) and initialize it.
To ensure the spread of blockchain technology, you must create your own cryptocurrency, which will help to quickly transfer data.
The goal is to be able to replicate as many commands as your network has nodes. For nodes to exchange data in a blockchain, they must be connected to each other. In order for Geth to connect to a node on the network and coordinate many actions, it must have its identifier called enode in Ethereum.
To ensure the spread of technology in the Ethereum ecosystem, it will be necessary to have cryptocurrency in Gas to get the necessary computing power from network participants.
4. Choose the most appropriate consensus protocol
The most important advantage of the blockchain is decentralization. This is a distributed database that the computers involved in it and called “nodes” jointly maintain. All nodes are registers, that is, they store the entire transaction history in a blockchain. The network cannot be destroyed by unloading any central server.
Information records, called “blocks”, are interconnected through a protocol program, and none of the existing blocks can be deleted or changed. Adding a new block is the only way to update a blockchain, any node can do this without any central command.
If a node ignores predefined standards and creates a block, other nodes ignore it. However, if an incompatible node continues to create blocks without adhering to standards and other nodes begin to create blocks on top of non-compliant blocks, then in the community will arise a conflict. A consensus mechanism is needed to prevent the emergence of incompatible nodes creating so-called forks.
There may be malicious nodes that suppress other network nodes using a “distributed denial of service” (DDoS) attack. Such nodes can trigger false actions. Preventing this also requires a consensus mechanism.
Choosing the right consensus protocol is a very important step in introducing the blockchain into the work of your organization, as it will greatly affect its operation and optimization. The main task of the consensus is to solve mathematical problems that require a large amount of computing power. For example, when one of the miners of a cryptocurrency finds the correct solution to a mathematical problem, the answer should be easily and quickly checked by all network participants, therefore there are different consensus systems, for example, Proof of Work (PoW) and Proof of Concept (PoC).
There are more than 25 consensus protocols, each of which has its own characteristics and disadvantages. The most popular at the moment are Proof of Work and Proof of Stake. They are the easiest to implement and understand.
Proof-of-Work (PoW) is used when the miner's technical equipment solves complex math problems. The miner receives a reward in the form of cryptocurrency for adding a verified block to the blockchain. Finding solutions is a complex process that requires significant computational power. As soon as the computer finds a solution, it sends a message to other computers in the community for verification. The solution is easy to verify because other computers are answered.
The key feature of this mathematical problem is asymmetry: it should be moderately difficult for the miner, but rather simple for the network as a whole. This is achieved using cryptography. Every miner in the network tries to find a solution to the problem first; at the same time, it can actually be found only by the brute force method, therefore, a successful solution requires many attempts.
Proof of Stake (PoS) is used when the miner blocks a predetermined number of coins to check a block of transactions. Cryptographic computing in PoS is much easier for computers. You need to prove only that you own a certain percentage of all coins available in a given currency. For example, if someone owns 2% of the total ether (ETH), he will be able to get 2% of all transactions through Ethereum. Some people think that PoS will be a fairer system than PoW, since technically anyone can become a miner. PoS offers a linear scale relative to the percentage of blocks that the miner can confirm based on the share of that person in the cryptocurrency. This means that a person who has ten times more coins can create only 10 times more blocks than another.
The idea of Proof-of-Stake was first proposed on the bitcointalk forum back in 2011; a year later, appeared the first cryptocurrencies using this method - Peercoin, ShadowCash, Nxt, BlackCoin, NuShares / NuBits, Qora and Nav Coin.