Bitcoin: a peer-to-peer electronic money system<\/a> It was published by Satoshi Nakamoto. The article describes the combination of cryptographic techniques and a peer-to-peer network without the need to rely on a centralized authority (as banks do) to make payments from one person to another. <\/p>\n\n\n\nThe same article introduces a distributed system for storing information (now called "blockchain"), which has a much wider field of application than just payments or cryptocurrencies.<\/p>\n\n\n\n
Since then, interest in the blockchain has grown practically in all sectors. So Blockchain is now the technology under fully digital cryptocurrencies like Bitcoin, distributed computing technologies like Ethereum<\/strong>, and open source frameworks like Hyperledger Fabric<\/strong>, on which the IBM Blockchain Platform<\/strong>.<\/p>\n\n\n\nThe term Blockchain refers to a chain of blocks that establish a record only<\/strong>, agreed upon <\/strong>Y distributed <\/strong>in several nodes of a network. In the case of cryptocurrencies, it could be said that it is the accounting bitacora where all transactions are recorded. That is, in each block it is stored:<\/p>\n\n\n\nA number of valid records or transactions<\/li> Information regarding that block<\/li> Your link with the previous block and the next block<\/li><\/ul>\n\n\n\nEach block has a unique identifier of the type hash <\/strong>which represents the fingerprint of the block.<\/p>\n\n\n\nIn this sense, each block has a specific place and immovable <\/strong>within the chain, since in each block there is information from the hash of the previous block, and the one linked to the later one. <\/p>\n\n\n\nThe entire chain is stored in each node of the network that makes up the blockchain, an exact copy of the chain is stored in everyone <\/strong>the participating nodes of the network.<\/p>\n\n\n\nAs new transactions or registrations are created, these are verified <\/strong>Y validated <\/strong>by the nodes of the network and later added to a new block that is linked to the chain.<\/p>\n\n\n\nDiagram of the block chain<\/figcaption><\/figure><\/div>\n\n\n\nSince it is a technology distributed <\/strong>where each node in the network stores an exact copy of the string, the availability <\/strong>of information is guaranteed at all times. If a node in the network suffers breakdowns or attacks, the information is available in the other nodes.<\/p>\n\n\n\nThe integrity <\/strong>of the information is also insured given that being a record agreed upon<\/strong>, all the nodes contain the same information and to alter the information it would be necessary to modify it in the whole chain or in at least 51% of the nodes.<\/p>\n\n\n\nAt the same time, since each block is linked to the next block, once a new block is added to the chain, it becomes unalterable<\/strong>, if a block is modified, its relation with the chain is broken, therefore, all the information registered in the blocks is immutable <\/strong>Y life<\/strong>.<\/p>\n\n\n\nIn this sense, blockchain allows you to store information that can never be lose, modify or eliminate<\/em><\/strong>.<\/p>\n\n\n\nCertificates and digital signatures are used in each node of the network to verify the information and validate the transactions, as well as the data stored in the chain, thus enabling the authenticity<\/strong> of the information.<\/p>\n\n\n\nUses of Blockchain<\/h3>\n\n\n\n Blockchain can be used to certify and validate any type of information, as well as store important documents, such as deeds without relying on third parties.<\/p>\n\n\n\n
In general, any type of information that needs to be preserved intact and that must remain available in a secure, decentralized and cheaper way than through intermediaries. If this information is stored encrypted, its confidentiality can be guaranteed since only those who have the encryption key will be able to access it.<\/p>\n\n\n\n
Health sector<\/h3>\n\n\n\n Health records could be unified and stored in blockchain so that patients' medical records are kept safe and at the same time available to each authorized physician, regardless of health service.<\/p>\n\n\n\n
The pharmaceutical industry could use blockchain to validate and verify medicines and thereby avoid counterfeiting.<\/p>\n\n\n\n
Internet of Things (IoT)<\/h3>\n\n\n\n The challenge for blockchain rests with the millions of devices connected to the Internet, given that the centralized model will not support the number of devices that are increasing every time. With blockchain devices can communicate through the network safely, directly and reliably, without intermediaries.<\/p>\n\n\n\n
As it mentioned above, Blockchain<\/strong> allows to verify, validate, track and store all types of information, from digital certificates, logistics and messaging services, smart contracts, money, financial transactions, as well as democratic election systems, among others.<\/p>\n\n\n\nThe Blockchain Council<\/h2>\n\n\n\n The Blockchain Council (Blockchain Council) is an authorized group of experts and enthusiasts whose work is to promote research, development and evangelize about cases of use, products and knowledge related to technology. Blockchain<\/strong> to achieve a better world.<\/p>\n\n\n\nThe Blockchain technology is emerging rapidly with a wide scope in the future. <\/p>\n\n\n\n
Blockchain acts as a financial network, a software, a distributed ledger, etc. Due to this great variety of benefits and characteristics, companies are now changing their centralized and traditional work system to this futuristic technology.<\/p>\n\n\n\n
The Blockchain board creates an environment and creates awareness among companies, developers and society by educating them on Blockchain topics. <\/p>\n\n\n\n
Programming for Blockchain<\/h3>\n\n\n\n The blockchain council has several courses and certifications<\/a> interesting to develop applications for blockchain, there are even tutorials to develop and implement a public blockchain from scratch with a simple application to deploy it.<\/p>\n\n\n\nCreate access points for different blockchain functions, such as adding a transaction using the Flask microframework, running the programs on multiple machines to create a decentralized network. The examples also show the development of a user interface to interact with the blockchain and store information for any use such as payments, peer-to-peer, conversations, electronic commerce, etc.<\/p>\n\n\n\n
<\/div>\n\n\n\n
\n\n\n\n
Blockchain with Python<\/h2>\n\n\n\n In this example, a public blockchain is created, managed by the server_id application, and information is stored in JSON format<\/p>\n\n\n\n
{"author": "author_name", "content": "Information the author wants to share", "timestamp": "The time the content was created"}\n<\/pre>\n\n\n\nserver_host.py<\/p>\n\n\n\n
\n 266 lines (203 sloc)\n
<\/span>\n 7.44 KB\n <\/div>\n\n \n
\n \n <\/td>\n desde<\/span> hashlib import<\/span> sha256<\/td>\n <\/tr>\n \n <\/td>\n import<\/span> json<\/td>\n <\/tr>\n \n <\/td>\n import<\/span> time<\/td>\n <\/tr>\n \n <\/td>\n \n <\/td>\n <\/tr>\n \n <\/td>\n desde<\/span> flask import<\/span> Flask, request<\/td>\n <\/tr>\n \n <\/td>\n import<\/span> requests<\/td>\n <\/tr>\n \n <\/td>\n \n <\/td>\n <\/tr>\n \n <\/td>\n \n <\/td>\n <\/tr>\n \n <\/td>\n class<\/span> Block<\/span>:<\/td>\n <\/tr>\n \n <\/td>\n def<\/span> __init__<\/span>(self<\/span><\/span>, index<\/span>, transactions<\/span>, timestamp<\/span>, previous_hash<\/span>):<\/td>\n <\/tr>\n \n <\/td>\n self<\/span>.index =<\/span> index<\/td>\n <\/tr>\n \n <\/td>\n self<\/span>.transactions =<\/span> transactions<\/td>\n <\/tr>\n \n <\/td>\n self<\/span>.timestamp =<\/span> timestamp<\/td>\n <\/tr>\n \n <\/td>\n self<\/span>.previous_hash =<\/span> previous_hash<\/td>\n <\/tr>\n \n <\/td>\n self<\/span>.nonce =<\/span> 0<\/span><\/td>\n <\/tr>\n \n <\/td>\n \n <\/td>\n <\/tr>\n \n <\/td>\n def<\/span> compute_hash<\/span>(self<\/span><\/span>):<\/td>\n <\/tr>\n \n <\/td>\n "" "<\/span><\/span><\/td>\n <\/tr>\n \n <\/td>\n A function that return the hash of the block contents.<\/span><\/td>\n <\/tr>\n \n <\/td>\n "" "<\/span><\/span><\/td>\n <\/tr>\n \n <\/td>\n block_string =<\/span> json.dumps (self<\/span>.__dict__<\/span>, sort_keys<\/span>=<\/span>True<\/span>)<\/td>\n <\/tr>\n \n <\/td>\n return<\/span> sha256 (block_string.encode ()). hexdigest ()<\/td>\n <\/tr>\n \n <\/td>\n \n <\/td>\n <\/tr>\n \n <\/td>\n \n <\/td>\n <\/tr>\n \n <\/td>\n class<\/span> Blockchain<\/span>:<\/td>\n <\/tr>\n \n <\/td>\n #<\/span> difficulty of our PoW algorithm<\/span><\/td>\n <\/tr>\n \n <\/td>\n difficulty =<\/span> 2<\/span><\/td>\n <\/tr>\n \n <\/td>\n \n <\/td>\n <\/tr>\n \n <\/td>\n def<\/span> __init__<\/span>(self<\/span><\/span>):<\/td>\n <\/tr>\n \n <\/td>\n self<\/span>.unconfirmed_transactions =<\/span> []<\/td>\n <\/tr>\n \n <\/td>\n self<\/span>.chain =<\/span> []<\/td>\n <\/tr>\n \n <\/td>\n self<\/span>.create_genesis_block ()<\/td>\n <\/tr>\n \n <\/td>\n \n <\/td>\n <\/tr>\n \n <\/td>\n def<\/span> create_genesis_block<\/span>(self<\/span><\/span>):<\/td>\n <\/tr>\n \n <\/td>\n "" "<\/span><\/span><\/td>\n <\/tr>\n \n <\/td>\n A function to generate genesis block and appends it to<\/span><\/td>\n <\/tr>\n \n <\/td>\n the chain. The block has index 0, previous_hash as 0, and<\/span><\/td>\n <\/tr>\n \n <\/td>\n a valid hash.<\/span><\/td>\n <\/tr>\n \n <\/td>\n "" "<\/span><\/span><\/td>\n <\/tr>\n \n <\/td>\n genesis_block =<\/span> Block (0<\/span>, [], time.time (), "<\/span>0"<\/span><\/span>)<\/td>\n <\/tr>\n \n <\/td>\n genesis_block.hash =<\/span> genesis_block.compute_hash ()<\/td>\n <\/tr>\n \n <\/td>\n self<\/span>.chain.append (genesis_block)<\/td>\n <\/tr>\n \n <\/td>\n \n <\/td>\n <\/tr>\n \n <\/td>\n @<\/span>property<\/span><\/td>\n <\/tr>\n \n <\/td>\n def<\/span> last_block<\/span>(self<\/span><\/span>):<\/td>\n <\/tr>\n \n <\/td>\n return<\/span> self<\/span>.chain [–<\/span>1<\/span>]<\/td>\n <\/tr>\n \n <\/td>\n \n <\/td>\n <\/tr>\n \n <\/td>\n def<\/span> add_block<\/span>(self<\/span><\/span>, block<\/span>, proof<\/span>):<\/td>\n <\/tr>\n \n <\/td>\n "" "<\/span><\/span><\/td>\n <\/tr>\n \n <\/td>\n A function that adds the block to the chain after verification.<\/span><\/td>\n <\/tr>\n \n <\/td>\n Verification includes:<\/span><\/td>\n <\/tr>\n \n <\/td>\n * Checking if the proof is valid.<\/span><\/td>\n <\/tr>\n \n <\/td>\n * The previous_hash referred to in the block and the hash of the last block<\/span><\/td>\n <\/tr>\n \n <\/td>\n in the chain match.<\/span><\/td>\n <\/tr>\n \n <\/td>\n "" "<\/span><\/span><\/td>\n <\/tr>\n \n <\/td>\n previous_hash =<\/span> self<\/span>.last_block.hash<\/td>\n <\/tr>\n \n
![\"\"](\"https:\/\/www.jacobsoft.com.mx\/wp-content\/uploads\/2018\/10\/blockchain_esquema.png\")