Karli  Langosh

Karli Langosh

1616638500

Build Your Own DevTools

Build Your Own DevTools

Diagnostics tools are not something you should build yourself in an hour…
Unless you want to learn about some great APIs available in Node.js
In this workshop, we’ll use async_hooks and perf_hooks for, yes you guessed it, fun and profit.

#node #api

What is GEEK

Buddha Community

Build Your Own DevTools

The Best Way to Build a Chatbot in 2021

A useful tool several businesses implement for answering questions that potential customers may have is a chatbot. Many programming languages give web designers several ways on how to make a chatbot for their websites. They are capable of answering basic questions for visitors and offer innovation for businesses.

With the help of programming languages, it is possible to create a chatbot from the ground up to satisfy someone’s needs.

Plan Out the Chatbot’s Purpose

Before building a chatbot, it is ideal for web designers to determine how it will function on a website. Several chatbot duties center around fulfilling customers’ needs and questions or compiling and optimizing data via transactions.

Some benefits of implementing chatbots include:

  • Generating leads for marketing products and services
  • Improve work capacity when employees cannot answer questions or during non-business hours
  • Reducing errors while providing accurate information to customers or visitors
  • Meeting customer demands through instant communication
  • Alerting customers about their online transactions

Some programmers may choose to design a chatbox to function through predefined answers based on the questions customers may input or function by adapting and learning via human input.

#chatbots #latest news #the best way to build a chatbot in 2021 #build #build a chatbot #best way to build a chatbot

Riyad Amin

Riyad Amin

1571046022

Build Your Own Cryptocurrency Blockchain in Python

Cryptocurrency is a decentralized digital currency that uses encryption techniques to regulate the generation of currency units and to verify the transfer of funds. Anonymity, decentralization, and security are among its main features. Cryptocurrency is not regulated or tracked by any centralized authority, government, or bank.

Blockchain, a decentralized peer-to-peer (P2P) network, which is comprised of data blocks, is an integral part of cryptocurrency. These blocks chronologically store information about transactions and adhere to a protocol for inter-node communication and validating new blocks. The data recorded in blocks cannot be altered without the alteration of all subsequent blocks.

In this article, we are going to explain how you can create a simple blockchain using the Python programming language.

Here is the basic blueprint of the Python class we’ll use for creating the blockchain:

class Block(object):
    def __init__():
        pass
    #initial structure of the block class 
    def compute_hash():
        pass
    #producing the cryptographic hash of each block 
  class BlockChain(object):
    def __init__(self):
    #building the chain
    def build_genesis(self):
        pass
    #creating the initial block
    def build_block(self, proof_number, previous_hash):
        pass
    #builds new block and adds to the chain
   @staticmethod
    def confirm_validity(block, previous_block):
        pass
    #checks whether the blockchain is valid
    def get_data(self, sender, receiver, amount):
        pass
    # declares data of transactions
    @staticmethod
    def proof_of_work(last_proof):
        pass
    #adds to the security of the blockchain
    @property
    def latest_block(self):
        pass
    #returns the last block in the chain

Now, let’s explain how the blockchain class works.

Initial Structure of the Block Class

Here is the code for our initial block class:

import hashlib
import time
class Block(object):
    def __init__(self, index, proof_number, previous_hash, data, timestamp=None):
        self.index = index
        self.proof_number = proof_number
        self.previous_hash = previous_hash
        self.data = data
        self.timestamp = timestamp or time.time()
    @property
    def compute_hash(self):
        string_block = "{}{}{}{}{}".format(self.index, self.proof_number, self.previous_hash, self.data, self.timestamp)
        return hashlib.sha256(string_block.encode()).hexdigest()

As you can see above, the class constructor or initiation method ( init()) above takes the following parameters:

self — just like any other Python class, this parameter is used to refer to the class itself. Any variable associated with the class can be accessed using it.

index — it’s used to track the position of a block within the blockchain.

previous_hash — it used to reference the hash of the previous block within the blockchain.

data—it gives details of the transactions done, for example, the amount bought.

timestamp—it inserts a timestamp for all the transactions performed.

The second method in the class, compute_hash , is used to produce the cryptographic hash of each block based on the above values.

As you can see, we imported the SHA-256 algorithm into the cryptocurrency blockchain project to help in getting the hashes of the blocks.

Once the values have been placed inside the hashing module, the algorithm will return a 256-bit string denoting the contents of the block.

So, this is what gives the blockchain immutability. Since each block will be represented by a hash, which will be computed from the hash of the previous block, corrupting any block in the chain will make the other blocks have invalid hashes, resulting in breakage of the whole blockchain network.

Building the Chain

The whole concept of a blockchain is based on the fact that the blocks are “chained” to each other. Now, we’ll create a blockchain class that will play the critical role of managing the entire chain.

It will keep the transactions data and include other helper methods for completing various roles, such as adding new blocks.

Let’s talk about the helper methods.

Adding the Constructor Method

Here is the code:

class BlockChain(object):
    def __init__(self):
        self.chain = []
        self.current_data = []
        self.nodes = set()
        self.build_genesis()

The init() constructor method is what instantiates the blockchain.

Here are the roles of its attributes:

self.chain — this variable stores all the blocks.

self.current_data — this variable stores information about the transactions in the block.

self.build_genesis() — this method is used to create the initial block in the chain.

Building the Genesis Block

The build_genesis() method is used for creating the initial block in the chain, that is, a block without any predecessors. The genesis block is what represents the beginning of the blockchain.

To create it, we’ll call the build_block() method and give it some default values. The parameters proof_number and previous_hash are both given a value of zero, though you can give them any value you desire.

Here is the code:

def build_genesis(self):
        self.build_block(proof_number=0, previous_hash=0)
 def build_block(self, proof_number, previous_hash):
        block = Block(
            index=len(self.chain),
            proof_number=proof_number,
            previous_hash=previous_hash,
            data=self.current_data
        )
        self.current_data = []  
        self.chain.append(block)
        return block

Confirming Validity of the Blockchain

The confirm_validity method is critical in examining the integrity of the blockchain and making sure inconsistencies are lacking.

As explained earlier, hashes are pivotal for realizing the security of the cryptocurrency blockchain, because any slight alteration in an object will result in the creation of an entirely different hash.

Thus, the confirm_validity method utilizes a series of if statements to assess whether the hash of each block has been compromised.

Furthermore, it also compares the hash values of every two successive blocks to identify any anomalies. If the chain is working properly, it returns true; otherwise, it returns false.

Here is the code:

def confirm_validity(block, previous_block):
        if previous_block.index + 1 != block.index:
            return False
        elif previous_block.compute_hash != block.previous_hash:
            return False
        elif block.timestamp <= previous_block.timestamp:
            return False
        return True

Declaring Data of Transactions

The get_data method is important in declaring the data of transactions on a block. This method takes three parameters (sender’s information, receiver’s information, and amount) and adds the transaction data to the self.current_data list.

Here is the code:

def get_data(self, sender, receiver, amount):
        self.current_data.append({
            'sender': sender,
            'receiver': receiver,
            'amount': amount
        })
        return True

Effecting the Proof of Work

In blockchain technology, Proof of Work (PoW) refers to the complexity involved in mining or generating new blocks on the blockchain.

For example, the PoW can be implemented by identifying a number that solves a problem whenever a user completes some computing work. Anyone on the blockchain network should find the number complex to identify but easy to verify — this is the main concept of PoW.

This way, it discourages spamming and compromising the integrity of the network.

In this article, we’ll illustrate how to include a Proof of Work algorithm in a blockchain cryptocurrency project.

Finalizing With the Last Block

Finally, the latest_block() helper method is used for retrieving the last block on the network, which is actually the current block.

Here is the code:

def latest_block(self):
        return self.chain[-1]

Implementing Blockchain Mining

Now, this is the most exciting section!

Initially, the transactions are kept in a list of unverified transactions. Mining refers to the process of placing the unverified transactions in a block and solving the PoW problem. It can be referred to as the computing work involved in verifying the transactions.

If everything has been figured out correctly, a block is created or mined and joined together with the others in the blockchain. If users have successfully mined a block, they are often rewarded for using their computing resources to solve the PoW problem.

Here is the mining method in this simple cryptocurrency blockchain project:

def block_mining(self, details_miner):
            self.get_data(
            sender="0", #it implies that this node has created a new block
            receiver=details_miner,
            quantity=1, #creating a new block (or identifying the proof number) is awarded with 1
        )
        last_block = self.latest_block
        last_proof_number = last_block.proof_number
        proof_number = self.proof_of_work(last_proof_number)
        last_hash = last_block.compute_hash
        block = self.build_block(proof_number, last_hash)
        return vars(block)

Summary

Here is the whole code for our crypto blockchain class in Python:

import hashlib
import time
class Block(object):
    def __init__(self, index, proof_number, previous_hash, data, timestamp=None):
        self.index = index
        self.proof_number = proof_number
        self.previous_hash = previous_hash
        self.data = data
        self.timestamp = timestamp or time.time()
    @property
    def compute_hash(self):
        string_block = "{}{}{}{}{}".format(self.index, self.proof_number, self.previous_hash, self.data, self.timestamp)
        return hashlib.sha256(string_block.encode()).hexdigest()
    def __repr__(self):
        return "{} - {} - {} - {} - {}".format(self.index, self.proof_number, self.previous_hash, self.data, self.timestamp)
class BlockChain(object):
    def __init__(self):
        self.chain = []
        self.current_data = []
        self.nodes = set()
        self.build_genesis()
    def build_genesis(self):
        self.build_block(proof_number=0, previous_hash=0)
    def build_block(self, proof_number, previous_hash):
        block = Block(
            index=len(self.chain),
            proof_number=proof_number,
            previous_hash=previous_hash,
            data=self.current_data
        )
        self.current_data = []  
        self.chain.append(block)
        return block
    @staticmethod
    def confirm_validity(block, previous_block):
        if previous_block.index + 1 != block.index:
            return False
        elif previous_block.compute_hash != block.previous_hash:
            return False
        elif block.timestamp <= previous_block.timestamp:
            return False
        return True
    def get_data(self, sender, receiver, amount):
        self.current_data.append({
            'sender': sender,
            'receiver': receiver,
            'amount': amount
        })
        return True        
    @staticmethod
    def proof_of_work(last_proof):
        pass
    @property
    def latest_block(self):
        return self.chain[-1]
    def chain_validity(self):
        pass        
    def block_mining(self, details_miner):       
        self.get_data(
            sender="0", #it implies that this node has created a new block
            receiver=details_miner,
            quantity=1, #creating a new block (or identifying the proof number) is awared with 1
        )
        last_block = self.latest_block
        last_proof_number = last_block.proof_number
        proof_number = self.proof_of_work(last_proof_number)
        last_hash = last_block.compute_hash
        block = self.build_block(proof_number, last_hash)
        return vars(block)  
    def create_node(self, address):
        self.nodes.add(address)
        return True
    @staticmethod
    def get_block_object(block_data):        
        return Block(
            block_data['index'],
            block_data['proof_number'],
            block_data['previous_hash'],
            block_data['data'],
            timestamp=block_data['timestamp']
        )
blockchain = BlockChain()
print("GET READY MINING ABOUT TO START")
print(blockchain.chain)
last_block = blockchain.latest_block
last_proof_number = last_block.proof_number
proof_number = blockchain.proof_of_work(last_proof_number)
blockchain.get_data(
    sender="0", #this means that this node has constructed another block
    receiver="LiveEdu.tv", 
    amount=1, #building a new block (or figuring out the proof number) is awarded with 1
)
last_hash = last_block.compute_hash
block = blockchain.build_block(proof_number, last_hash)
print("WOW, MINING HAS BEEN SUCCESSFUL!")
print(blockchain.chain)

Now, let’s try to run our code to see if we can generate some digital coins…

Wow, it worked!

Conclusion

That is it!

We hope that this article has assisted you to understand the underlying technology that powers cryptocurrencies such as Bitcoin and Ethereum.

We just illustrated the basic ideas for making your feet wet in the innovative blockchain technology. The project above can still be enhanced by incorporating other features to make it more useful and robust.

Learn More

Thanks for reading !

Do you have any comments or questions? Please share them below.

#python #cryptocurrency

What is BUILD Finance (BUILD) | What is BUILD Finance token | What is BUILD token

BUILD Finance DAO

The document is non-binding. Some information may be outdated as we keep evolving.

BUILD Philosophy

BUILD Finance is a decentralised autonomous venture builder, owned and controlled by the community. BUILD Finance produces, funds, and manages community-owned DeFi products.

There are five core activities in which the venture BUILDers engage:

  1. Identifying business ideas,
  2. Organising teams,
  3. Sourcing capital,
  4. Helping govern the product entities, and
  5. Providing shared services.

BUILD operates a shared capabilities model, where the DAO provides the backbone support and ensures inter-entity synergies so that the product companies can focus on their own outcomes.

BUILD takes care of all organisational, hiring, back/mid office functions, and the product companies focus on what they can do best, until such time where any individual product outgrows the DAO and becomes fully self-sustainable. At that point, the chick is strong enough to leave the nest and live its own life. The survival of the fittest. No product entity is held within DAO by force.

Along the way, BUILD utilises the investment banking model, which, in its essence, is a process of creating assets, gearing them up, and then flipping them into a fund or setting them as income-generating business systems, all this while taking fees along the way at each step. BUILD heavily focuses on integrating each asset/product with each other to boost productive yield and revenues. For example, BUILD’s OTC Market may be integrated with Metric Exchange to connect the liquidity pools with the trading traffic. The net result – pure synergy that benefits each party involved, acting in a self-reinforcing manner.

El Espíritu de la Colmena (The Spirit of the Beehive)

BUILD is a hive and is always alive. While some members may appear more active than others, there’s no central source of control or “core teams” as such. BUILD is work in progress where everyone is encouraged to contribute.

Following the natural free market forces, BUILD only works on those products that members are wanting to work on themselves and that they believe have economic value. Effectively, every builder is also a user of BUILD’s products. We are DeFi users that fill the gaps in the ecosystem. Any member can contribute from both purely altruistic or ultra-mercantile intentions – it’s up to the wider community to decide what is deemed valuable and what product to support. The BUILD community is a sovereign individual that votes with their money and feet.

BUILD members = BUILD users. It’s that simple.

$BUILD TOKEN

Tokenomics

$BUILD token is used as a governance token for the DAO. It also represents a pro-rata claim of ownership on all DAO’s assets and liabilities (e.g. BUILD Treasury and $bCRED debt token).

The token was distributed via liquidity mining with no pre-sale and zero founder/private allocation. The farming event lasted for 7 days around mid-Sep 2020. At the time, BUILD didn’t have any products and held no value. Arguably, $BUILD has still zero value as it is not a legal instrument and does not guarantee or promise any returns to anyone. See the launch announcement here https://medium.com/@BUILD_Finance/announcing-build-finance-dc08df585e57​

Initial supply was 100,000 $BUILD with 100% distributed via fair launch. Subsequently, the DAO unanimously voted to approve minting of extra 30,000 $BUILD and allocate them as:

  • 15,000 $BUILD (11.5%) to the founding member of the DAO (@0xdev0) with 1-year gradual vesting, and
  • 15,000 $BUILD (11.5%) to the DAO treasury as development funds.

For the proposal of the above see: https://forum.letsbuild.finance/t/proposal-2-fund-the-development-of-defi-lending-platform/24​

The voting took place at a later retired web-page https://vote.letsbuild.finance. The governance has since moved to Snapshot (link below). The results of the old proposals are not visible there, however, on-chain voting contract can be see here: https://etherscan.io/address/0xa8621477645f76b06a41c9393ddaf79ddee63daf#readContract​

$Build Token Repartition

Vesting Schedule

Minting keys are not burnt = $BUILD supply is not fixed as token holders can vote on minting new tokens for specific reasons determined by the token holders. For example, the DAO may mint additional tokens to incentivise usage of its products, which would, in turn, increase the value flow or TVL. Dilution is not in the economic benefit of the token holders, hence any such events has to be considered carefully.

Access to minting function is available via on-chain governance. A safe buffer is established in a form of the contract-enforced 24 hour delay, which should provide a sufficient time for the community to flag. Meaning that before such a transaction could be executed, everyone would be able to act in advance by withdrawing their funds / exiting from BUILD. Any malicious minting would, theoretically, result in an immediate market sell-off of $BUILD, making it economically detrimental to do such an action. This makes it highly improbable that any malicious minting would be performed_._

GOVERNANCE

All components of the BUILD DAO and the control over its have been decentralised:

  • All contracts (incl. the Treasury and Basis Gold) can be operated by $BUILD holders with on-chain proposals (see https://docs.build.finance/build-knowledge-base/on-chain-voting);
  • All social accounts (Discord, Telegram, and Twitter) are managed by multiple moderators;
  • All frontends (Metric Exchange, Basis Gold, and the BUILD homepage) are auto-deployed and managed by multiple devs.

TREASURY & DEVELOPMENT

BUILD DAO Treasury

The BUILD treasury has over $400k that can be managed by on-chain proposals and used in whichever way the community desires. For example, to hire developers. Having a functioning product, enough funds in the treasury and a fully decentralised governance has been a long-term goal since the inception in September 2020, and now it’s finally here.

Current holdings are (might be outdated):

  • Capital budget (dev / incentives fund) - 11,025 $BUILD (~$94k);
  • Operational budget (product development) - 204,300 $aDAI;
  • Ownership stake - 200,000 $METRIC (~$84k);
  • Ownership stake - 199,900 $UPDOWN(~$62k);
  • Ownership stake - 5,400 $HYPE (~$1.3k);
  • Ownership stake - 2% of $BSGS supply.
  • TOTAL: ~$445k

Funding of the Development

In an early stage, the development will be funded by an allocation of bCRED debt tokens for development expenses. After the first product was built (i.e. Metric Exchange), the DAO sold 5,000 $BUILD for 203,849 $DAI which will now be used for funding of other products or a combination of revenue + a smaller token allocation. This is up to the community to decide.

Smart Contract Audit

Contracts are not audited. It’s up to the BUILD community governance to decide how to spend our funds. If the community wants to spend any amount for auditing, a voting proposal can be initiated. As with any decisions and proposals, the cost-benefit analysis must be employed in regards to the economical sense of spending any funds on audit vs developing more products and expanding our revenue streams.

DAO Liabilities and $bCRED

$bCRED is a token that allowed the DAO to reward members for work before the DAO source sufficient funds. Effectively, $bCRED is a promissory note or an IOU to give back $DAI at 1:1 ratio, when the DAO starts generating revenues. Read more about $bCRED here: https://medium.com/@BUILD_Finance/what-is-bcred-b97e4cc75f8c.

“BUILDER” User Role in Discord

Since Discord is our primary coordination mechanism, we need to make effort to keep it focused on producing value. During the launch of METRIC, we’ve doubled our total number of users! This made it very difficult for existing users to explain what BUILD is about to new users and created a lot of confusion.

To help improve the quality of conversations, we’ve introduced a new user role called BUILDer. BUILDers will have write-access to product development channels while everyone else will only be able to read them. This should keep those product changes focused on actual productive conversations and make them more informative.

“GUARDIAN” Role in Discord

To increase our collective output as a community, a governance vote introduced an incentivisation mechanism for community contribution, tipping, and other small projects using our unique bCRED token (but may change in the future as required). These tokens are stewarded by active community members — “guardians’’ — who are free to allocate these funds to tip people for proactive work. Current guardians are @Son of Ishtar and @0xdev0, although anyone can propose the tip for anyone else. For more details see Proposal #15.

Hence, Guardians are defined as members of the DAO who are entrusted with a community budget for tipping other members for performing various small tasks.

PRODUCT SUITE & ROADMAP

  • Metric Exchange - is a DEX aggregator that allows for limit orders trading for any ERC-20 token via 0x relayer. Development continues with the product owner SHA_2048 and inputs from vfat. Live at metric.exchange.
  • Basis Gold - a synthetic, algorythmically-adjusted token pegged to the price of gold (sXAU) with elastic supply. Live at https://basis.gold/.
  • Updown Finance - binary options for volatility trading instrument (alpha is live at updown.finance).
  • Vortex - a lending & borrowing platform, which will target the long tail of assets that are currently not served by the existing DeFi money markets. Aiming to launch by March’2021.

The other immediate focus right now will be to make good use of our newly available funding and hire several product managers for other projects.

Please note that nothing is here set in stone. Just like any other start-up, we’ll keep experimenting, learning, and evolving. What’s listed here is just our current trajectory but it might change at any point.

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Thank you for reading!

#blockchain #cryptocurrency #build finance #build

Создайте свой собственный блокчейн криптовалюты на Python

Криптовалюта - это децентрализованная цифровая валюта, в которой используются методы шифрования для регулирования генерации денежных единиц и проверки перевода средств. Анонимность, децентрализация и безопасность - одни из его основных характеристик. Криптовалюта не регулируется и не отслеживается каким-либо централизованным органом, правительством или банком.

Блокчейн, децентрализованная одноранговая (P2P) сеть, состоящая из блоков данных, является неотъемлемой частью криптовалюты. Эти блоки хранят информацию о транзакциях в хронологическом порядке и придерживаются протокола для межузловой связи и проверки новых блоков. Данные, записанные в блоках, не могут быть изменены без изменения всех последующих блоков.

В этой статье мы собираемся объяснить, как создать простой блокчейн с помощью языка программирования Python.

Вот базовый план класса Python, который мы будем использовать для создания блокчейна:

class Block(object):
    def __init__():
        pass
    #initial structure of the block class 
    def compute_hash():
        pass
    #producing the cryptographic hash of each block 
  class BlockChain(object):
    def __init__(self):
    #building the chain
    def build_genesis(self):
        pass
    #creating the initial block
    def build_block(self, proof_number, previous_hash):
        pass
    #builds new block and adds to the chain
   @staticmethod
    def confirm_validity(block, previous_block):
        pass
    #checks whether the blockchain is valid
    def get_data(self, sender, receiver, amount):
        pass
    # declares data of transactions
    @staticmethod
    def proof_of_work(last_proof):
        pass
    #adds to the security of the blockchain
    @property
    def latest_block(self):
        pass
    #returns the last block in the chain

Теперь давайте объясним, как работает класс блокчейна.

Начальная структура класса блоков

Вот код нашего начального класса блока:

import hashlib
import time
class Block(object):
    def __init__(self, index, proof_number, previous_hash, data, timestamp=None):
        self.index = index
        self.proof_number = proof_number
        self.previous_hash = previous_hash
        self.data = data
        self.timestamp = timestamp or time.time()
    @property
    def compute_hash(self):
        string_block = "{}{}{}{}{}".format(self.index, self.proof_number, self.previous_hash, self.data, self.timestamp)
        return hashlib.sha256(string_block.encode()).hexdigest()

Как вы можете видеть выше, конструктор класса или метод инициации ( init ()) выше принимает следующие параметры:

self- как и любой другой класс Python, этот параметр используется для ссылки на сам класс. С его помощью можно получить доступ к любой переменной, связанной с классом.

index - он используется для отслеживания положения блока в цепочке блоков.

previous_hash - он использовался для ссылки на хэш предыдущего блока в цепочке блоков.

data—it предоставляет подробную информацию о проведенных транзакциях, например, купленную сумму.

timestamp—it вставляет отметку времени для всех выполненных транзакций.

Второй метод в классе, compute_hash, используется для создания криптографического хэша каждого блока на основе вышеуказанных значений.

Как видите, мы импортировали алгоритм SHA-256 в проект блокчейна криптовалюты, чтобы помочь в получении хэшей блоков.

Как только значения будут помещены в модуль хеширования, алгоритм вернет 256-битную строку, обозначающую содержимое блока.

Итак, это то, что дает неизменяемость блокчейна. Поскольку каждый блок будет представлен хешем, который будет вычисляться из хеша предыдущего блока, повреждение любого блока в цепочке приведет к тому, что другие блоки будут иметь недопустимые хеши, что приведет к поломке всей сети блокчейна.

Построение цепочки

Вся концепция блокчейна основана на том факте, что блоки «связаны» друг с другом. Теперь мы создадим класс цепочки блоков, который будет играть важную роль в управлении всей цепочкой.

Он будет хранить данные транзакций и включать другие вспомогательные методы для выполнения различных ролей, таких как добавление новых блоков.

Поговорим о вспомогательных методах.

Добавление метода конструктора

Вот код:

class BlockChain(object):
    def __init__(self):
        self.chain = []
        self.current_data = []
        self.nodes = set()
        self.build_genesis()

Метод конструктора init () - это то, что создает экземпляр блокчейна.

Вот роли его атрибутов:

self.chain - в этой переменной хранятся все блоки.

self.current_data - в этой переменной хранится информация о транзакциях в блоке.

self.build_genesis () - этот метод используется для создания начального блока в цепочке.

Создание блока генезиса

build_genesis()Метод используется для создания начального блока в цепочке, то есть, блок без каких - либо предшественников. Блок генезиса - это то, что представляет собой начало блокчейна.

Чтобы создать его, мы вызовем build_block()метод и дадим ему значения по умолчанию. Оба параметра proof_numberи previous_hashимеют нулевое значение, хотя вы можете присвоить им любое значение, которое пожелаете.

Вот код:

def build_genesis(self):
        self.build_block(proof_number=0, previous_hash=0)
 def build_block(self, proof_number, previous_hash):
        block = Block(
            index=len(self.chain),
            proof_number=proof_number,
            previous_hash=previous_hash,
            data=self.current_data
        )
        self.current_data = []  
        self.chain.append(block)
        return block

Подтверждение действительности блокчейна

Этот confirm_validityметод имеет решающее значение для проверки целостности цепочки блоков и проверки отсутствия несоответствий.

Как объяснялось ранее, хэши имеют решающее значение для обеспечения безопасности блокчейна криптовалюты, потому что любое небольшое изменение в объекте приведет к созданию совершенно другого хэша.

Таким образом, confirm_validityметод использует серию операторов if для оценки того, был ли скомпрометирован хэш каждого блока.

Кроме того, он также сравнивает хеш-значения каждых двух последовательных блоков для выявления любых аномалий. Если цепочка работает правильно, возвращается истина; в противном случае возвращается false.

Вот код:

def confirm_validity(block, previous_block):
        if previous_block.index + 1 != block.index:
            return False
        elif previous_block.compute_hash != block.previous_hash:
            return False
        elif block.timestamp <= previous_block.timestamp:
            return False
        return True

Объявление данных транзакций

get_dataМетод имеет важное значение в объявлении данных об операциях на блоке. Этот метод принимает три параметра (информацию об отправителе, информацию о получателе и сумму) и добавляет данные транзакции в список self.current_data.

Вот код:

def get_data(self, sender, receiver, amount):
        self.current_data.append({
            'sender': sender,
            'receiver': receiver,
            'amount': amount
        })
        return True

Выполнение доказательства работы

В технологии блокчейн Proof of Work (PoW) относится к сложности, связанной с майнингом или генерацией новых блоков в блокчейне.

Например, PoW может быть реализован путем определения числа, которое решает проблему всякий раз, когда пользователь выполняет некоторую вычислительную работу. Любой в сети блокчейн должен найти номер сложным для идентификации, но легким для проверки - это основная концепция PoW.

Таким образом, это препятствует распространению спама и нарушению целостности сети.

В этой статье мы покажем, как включить алгоритм Proof of Work в проект криптовалюты на блокчейне.

Завершение с последним блоком

Наконец, вспомогательный метод latest_block () используется для получения последнего блока в сети, который на самом деле является текущим блоком.

Вот код:

def latest_block(self):
        return self.chain[-1]

Внедрение Blockchain Mining

Теперь это самый интересный раздел!

Изначально транзакции хранятся в списке непроверенных транзакций. Майнинг относится к процессу размещения непроверенных транзакций в блоке и решения проблемы PoW. Это можно назвать вычислительной работой, связанной с проверкой транзакций.

Если все было правильно выяснено, блок создается или добывается и объединяется вместе с другими в цепочке блоков. Если пользователи успешно добыли блок, они часто получают вознаграждение за использование своих вычислительных ресурсов для решения проблемы PoW.

Вот метод майнинга в этом простом проекте блокчейна криптовалюты:

def block_mining(self, details_miner):
            self.get_data(
            sender="0", #it implies that this node has created a new block
            receiver=details_miner,
            quantity=1, #creating a new block (or identifying the proof number) is awarded with 1
        )
        last_block = self.latest_block
        last_proof_number = last_block.proof_number
        proof_number = self.proof_of_work(last_proof_number)
        last_hash = last_block.compute_hash
        block = self.build_block(proof_number, last_hash)
        return vars(block)

Резюме

Вот весь код нашего класса криптоблокчейна на Python:

import hashlib
import time
class Block(object):
    def __init__(self, index, proof_number, previous_hash, data, timestamp=None):
        self.index = index
        self.proof_number = proof_number
        self.previous_hash = previous_hash
        self.data = data
        self.timestamp = timestamp or time.time()
    @property
    def compute_hash(self):
        string_block = "{}{}{}{}{}".format(self.index, self.proof_number, self.previous_hash, self.data, self.timestamp)
        return hashlib.sha256(string_block.encode()).hexdigest()
    def __repr__(self):
        return "{} - {} - {} - {} - {}".format(self.index, self.proof_number, self.previous_hash, self.data, self.timestamp)
class BlockChain(object):
    def __init__(self):
        self.chain = []
        self.current_data = []
        self.nodes = set()
        self.build_genesis()
    def build_genesis(self):
        self.build_block(proof_number=0, previous_hash=0)
    def build_block(self, proof_number, previous_hash):
        block = Block(
            index=len(self.chain),
            proof_number=proof_number,
            previous_hash=previous_hash,
            data=self.current_data
        )
        self.current_data = []  
        self.chain.append(block)
        return block
    @staticmethod
    def confirm_validity(block, previous_block):
        if previous_block.index + 1 != block.index:
            return False
        elif previous_block.compute_hash != block.previous_hash:
            return False
        elif block.timestamp <= previous_block.timestamp:
            return False
        return True
    def get_data(self, sender, receiver, amount):
        self.current_data.append({
            'sender': sender,
            'receiver': receiver,
            'amount': amount
        })
        return True        
    @staticmethod
    def proof_of_work(last_proof):
        pass
    @property
    def latest_block(self):
        return self.chain[-1]
    def chain_validity(self):
        pass        
    def block_mining(self, details_miner):       
        self.get_data(
            sender="0", #it implies that this node has created a new block
            receiver=details_miner,
            quantity=1, #creating a new block (or identifying the proof number) is awared with 1
        )
        last_block = self.latest_block
        last_proof_number = last_block.proof_number
        proof_number = self.proof_of_work(last_proof_number)
        last_hash = last_block.compute_hash
        block = self.build_block(proof_number, last_hash)
        return vars(block)  
    def create_node(self, address):
        self.nodes.add(address)
        return True
    @staticmethod
    def get_block_object(block_data):        
        return Block(
            block_data['index'],
            block_data['proof_number'],
            block_data['previous_hash'],
            block_data['data'],
            timestamp=block_data['timestamp']
        )
blockchain = BlockChain()
print("GET READY MINING ABOUT TO START")
print(blockchain.chain)
last_block = blockchain.latest_block
last_proof_number = last_block.proof_number
proof_number = blockchain.proof_of_work(last_proof_number)
blockchain.get_data(
    sender="0", #this means that this node has constructed another block
    receiver="LiveEdu.tv", 
    amount=1, #building a new block (or figuring out the proof number) is awarded with 1
)
last_hash = last_block.compute_hash
block = blockchain.build_block(proof_number, last_hash)
print("WOW, MINING HAS BEEN SUCCESSFUL!")
print(blockchain.chain)

Теперь давайте попробуем запустить наш код, чтобы посмотреть, сможем ли мы сгенерировать несколько цифровых монет ...

Вау, сработало!

Заключение

Вот и все!

Мы надеемся, что эта статья помогла вам понять базовую технологию, на которой работают такие криптовалюты, как Биткойн и Эфириум.

Мы просто проиллюстрировали основные идеи, как сделать ваши ноги влажными в инновационной технологии блокчейн. Вышеупомянутый проект все еще можно улучшить, добавив другие функции, чтобы сделать его более полезным и надежным.

Construisez votre propre blockchain de crypto-monnaie en Python

La crypto-monnaie est une monnaie numérique décentralisée qui utilise des techniques de cryptage pour réguler la génération d'unités monétaires et vérifier le transfert de fonds. L'anonymat, la décentralisation et la sécurité font partie de ses principales caractéristiques. La crypto-monnaie n'est réglementée ou suivie par aucune autorité centralisée, gouvernement ou banque.

Blockchain, un réseau peer-to-peer décentralisé (P2P), composé de blocs de données, fait partie intégrante de la crypto-monnaie. Ces blocs stockent chronologiquement des informations sur les transactions et adhèrent à un protocole de communication inter-nœuds et de validation de nouveaux blocs. Les données enregistrées dans les blocs ne peuvent pas être modifiées sans la modification de tous les blocs suivants.

Dans cet article, nous allons expliquer comment créer une blockchain simple à l'aide du langage de programmation Python.

Voici le plan de base de la classe Python que nous utiliserons pour créer la blockchain :

class Block(object):
    def __init__():
        pass
    #initial structure of the block class 
    def compute_hash():
        pass
    #producing the cryptographic hash of each block 
  class BlockChain(object):
    def __init__(self):
    #building the chain
    def build_genesis(self):
        pass
    #creating the initial block
    def build_block(self, proof_number, previous_hash):
        pass
    #builds new block and adds to the chain
   @staticmethod
    def confirm_validity(block, previous_block):
        pass
    #checks whether the blockchain is valid
    def get_data(self, sender, receiver, amount):
        pass
    # declares data of transactions
    @staticmethod
    def proof_of_work(last_proof):
        pass
    #adds to the security of the blockchain
    @property
    def latest_block(self):
        pass
    #returns the last block in the chain

Maintenant, expliquons comment fonctionne la classe blockchain.

Structure initiale de la classe Block

Voici le code de notre classe de bloc initiale :

import hashlib
import time
class Block(object):
    def __init__(self, index, proof_number, previous_hash, data, timestamp=None):
        self.index = index
        self.proof_number = proof_number
        self.previous_hash = previous_hash
        self.data = data
        self.timestamp = timestamp or time.time()
    @property
    def compute_hash(self):
        string_block = "{}{}{}{}{}".format(self.index, self.proof_number, self.previous_hash, self.data, self.timestamp)
        return hashlib.sha256(string_block.encode()).hexdigest()

Comme vous pouvez le voir ci-dessus, le constructeur de classe ou la méthode d'initiation ( init ()) ci-dessus prend les paramètres suivants :

self— comme toute autre classe Python, ce paramètre est utilisé pour faire référence à la classe elle-même. Toute variable associée à la classe est accessible en l'utilisant.

index - il est utilisé pour suivre la position d'un bloc dans la blockchain.

previous_hash — il faisait référence au hachage du bloc précédent dans la blockchain.

data—it donne des détails sur les transactions effectuées, par exemple, le montant acheté.

timestamp—it insère un horodatage pour toutes les transactions effectuées.

La deuxième méthode de la classe, compute_hash , est utilisée pour produire le hachage cryptographique de chaque bloc en fonction des valeurs ci-dessus.

Comme vous pouvez le voir, nous avons importé l'algorithme SHA-256 dans le projet de blockchain de crypto-monnaie pour aider à obtenir les hachages des blocs.

Une fois les valeurs placées dans le module de hachage, l'algorithme renvoie une chaîne de 256 bits indiquant le contenu du bloc.

C'est donc ce qui donne à la blockchain l'immuabilité. Étant donné que chaque bloc sera représenté par un hachage, qui sera calculé à partir du hachage du bloc précédent, la corruption de n'importe quel bloc de la chaîne fera que les autres blocs auront des hachages invalides, entraînant la rupture de l'ensemble du réseau blockchain.

Construire la chaîne

Tout le concept d'une blockchain est basé sur le fait que les blocs sont « enchaînés » les uns aux autres. Maintenant, nous allons créer une classe blockchain qui jouera le rôle essentiel de gestion de l'ensemble de la chaîne.

Il conservera les données des transactions et inclura d'autres méthodes d'assistance pour remplir divers rôles, tels que l'ajout de nouveaux blocs.

Parlons des méthodes d'aide.

Ajout de la méthode constructeur

Voici le code :

class BlockChain(object):
    def __init__(self):
        self.chain = []
        self.current_data = []
        self.nodes = set()
        self.build_genesis()

La méthode constructeur init () est ce qui instancie la blockchain.

Voici les rôles de ses attributs :

self.chain — cette variable stocke tous les blocs.

self.current_data — cette variable stocke des informations sur les transactions dans le bloc.

self.build_genesis() — cette méthode est utilisée pour créer le bloc initial de la chaîne.

Construire le bloc Genesis

La build_genesis()méthode est utilisée pour créer le bloc initial dans la chaîne, c'est-à-dire un bloc sans aucun prédécesseur. Le bloc de genèse est ce qui représente le début de la blockchain.

Pour le créer, nous appellerons la build_block()méthode et lui donnerons des valeurs par défaut. Les paramètres proof_numberet previous_hashreçoivent tous deux une valeur de zéro, bien que vous puissiez leur donner la valeur que vous désirez.

Voici le code :

def build_genesis(self):
        self.build_block(proof_number=0, previous_hash=0)
 def build_block(self, proof_number, previous_hash):
        block = Block(
            index=len(self.chain),
            proof_number=proof_number,
            previous_hash=previous_hash,
            data=self.current_data
        )
        self.current_data = []  
        self.chain.append(block)
        return block

Confirmation de la validité de la blockchain

La confirm_validityméthode est essentielle pour examiner l'intégrité de la blockchain et s'assurer qu'il n'y a pas d'incohérences.

Comme expliqué précédemment, les hachages sont essentiels pour assurer la sécurité de la blockchain de crypto-monnaie, car toute légère modification d'un objet entraînera la création d'un hachage entièrement différent.

Ainsi, le confirm_validityprocédé utilise une série d'instructions if pour évaluer si le hachage de chaque bloc a été compromis.

De plus, il compare également les valeurs de hachage de tous les deux blocs successifs pour identifier toute anomalie. Si la chaîne fonctionne correctement, elle renvoie true ; sinon, il retourne faux.

Voici le code :

def confirm_validity(block, previous_block):
        if previous_block.index + 1 != block.index:
            return False
        elif previous_block.compute_hash != block.previous_hash:
            return False
        elif block.timestamp <= previous_block.timestamp:
            return False
        return True

Déclaration des données des transactions

La get_dataméthode est importante pour déclarer les données des transactions sur un bloc. Cette méthode prend trois paramètres (informations de l'expéditeur, informations du destinataire et montant) et ajoute les données de transaction à la liste self.current_data.

Voici le code :

def get_data(self, sender, receiver, amount):
        self.current_data.append({
            'sender': sender,
            'receiver': receiver,
            'amount': amount
        })
        return True

Effectuer la preuve de travail

Dans la technologie blockchain, la preuve de travail (PoW) fait référence à la complexité impliquée dans l'extraction ou la génération de nouveaux blocs sur la blockchain.

Par exemple, le PoW peut être mis en œuvre en identifiant un numéro qui résout un problème chaque fois qu'un utilisateur effectue un travail informatique. Toute personne sur le réseau blockchain devrait trouver le numéro complexe à identifier mais facile à vérifier - c'est le concept principal de PoW.

De cette façon, cela décourage le spam et compromet l'intégrité du réseau.

Dans cet article, nous allons illustrer comment inclure un algorithme de preuve de travail dans un projet de crypto-monnaie blockchain.

Finaliser avec le dernier bloc

Enfin, la méthode helper last_block() est utilisée pour récupérer le dernier bloc sur le réseau, qui est en fait le bloc actuel.

Voici le code :

def latest_block(self):
        return self.chain[-1]

Mise en œuvre du minage de la blockchain

Maintenant, c'est la section la plus excitante!

Initialement, les transactions sont conservées dans une liste de transactions non vérifiées. Le minage fait référence au processus consistant à placer les transactions non vérifiées dans un bloc et à résoudre le problème de PoW. Il peut être appelé le travail informatique impliqué dans la vérification des transactions.

Si tout a été compris correctement, un bloc est créé ou extrait et joint aux autres dans la blockchain. Si les utilisateurs ont réussi à exploiter un bloc, ils sont souvent récompensés pour avoir utilisé leurs ressources informatiques pour résoudre le problème de PoW.

Voici la méthode de minage dans ce projet simple de blockchain de crypto-monnaie :

def block_mining(self, details_miner):
            self.get_data(
            sender="0", #it implies that this node has created a new block
            receiver=details_miner,
            quantity=1, #creating a new block (or identifying the proof number) is awarded with 1
        )
        last_block = self.latest_block
        last_proof_number = last_block.proof_number
        proof_number = self.proof_of_work(last_proof_number)
        last_hash = last_block.compute_hash
        block = self.build_block(proof_number, last_hash)
        return vars(block)

Sommaire

Voici le code complet de notre classe crypto blockchain en Python :

import hashlib
import time
class Block(object):
    def __init__(self, index, proof_number, previous_hash, data, timestamp=None):
        self.index = index
        self.proof_number = proof_number
        self.previous_hash = previous_hash
        self.data = data
        self.timestamp = timestamp or time.time()
    @property
    def compute_hash(self):
        string_block = "{}{}{}{}{}".format(self.index, self.proof_number, self.previous_hash, self.data, self.timestamp)
        return hashlib.sha256(string_block.encode()).hexdigest()
    def __repr__(self):
        return "{} - {} - {} - {} - {}".format(self.index, self.proof_number, self.previous_hash, self.data, self.timestamp)
class BlockChain(object):
    def __init__(self):
        self.chain = []
        self.current_data = []
        self.nodes = set()
        self.build_genesis()
    def build_genesis(self):
        self.build_block(proof_number=0, previous_hash=0)
    def build_block(self, proof_number, previous_hash):
        block = Block(
            index=len(self.chain),
            proof_number=proof_number,
            previous_hash=previous_hash,
            data=self.current_data
        )
        self.current_data = []  
        self.chain.append(block)
        return block
    @staticmethod
    def confirm_validity(block, previous_block):
        if previous_block.index + 1 != block.index:
            return False
        elif previous_block.compute_hash != block.previous_hash:
            return False
        elif block.timestamp <= previous_block.timestamp:
            return False
        return True
    def get_data(self, sender, receiver, amount):
        self.current_data.append({
            'sender': sender,
            'receiver': receiver,
            'amount': amount
        })
        return True        
    @staticmethod
    def proof_of_work(last_proof):
        pass
    @property
    def latest_block(self):
        return self.chain[-1]
    def chain_validity(self):
        pass        
    def block_mining(self, details_miner):       
        self.get_data(
            sender="0", #it implies that this node has created a new block
            receiver=details_miner,
            quantity=1, #creating a new block (or identifying the proof number) is awared with 1
        )
        last_block = self.latest_block
        last_proof_number = last_block.proof_number
        proof_number = self.proof_of_work(last_proof_number)
        last_hash = last_block.compute_hash
        block = self.build_block(proof_number, last_hash)
        return vars(block)  
    def create_node(self, address):
        self.nodes.add(address)
        return True
    @staticmethod
    def get_block_object(block_data):        
        return Block(
            block_data['index'],
            block_data['proof_number'],
            block_data['previous_hash'],
            block_data['data'],
            timestamp=block_data['timestamp']
        )
blockchain = BlockChain()
print("GET READY MINING ABOUT TO START")
print(blockchain.chain)
last_block = blockchain.latest_block
last_proof_number = last_block.proof_number
proof_number = blockchain.proof_of_work(last_proof_number)
blockchain.get_data(
    sender="0", #this means that this node has constructed another block
    receiver="LiveEdu.tv", 
    amount=1, #building a new block (or figuring out the proof number) is awarded with 1
)
last_hash = last_block.compute_hash
block = blockchain.build_block(proof_number, last_hash)
print("WOW, MINING HAS BEEN SUCCESSFUL!")
print(blockchain.chain)

Maintenant, essayons d'exécuter notre code pour voir si nous pouvons générer des pièces numériques…

Waouh, ça a marché !

Conclusion

C'est ça!

Nous espérons que cet article vous a aidé à comprendre la technologie sous-jacente qui alimente les crypto-monnaies telles que Bitcoin et Ethereum.

Nous venons d'illustrer les idées de base pour se mouiller les pieds dans la technologie innovante de la blockchain. Le projet ci-dessus peut encore être amélioré en incorporant d'autres fonctionnalités pour le rendre plus utile et robuste.