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Blockchain Android Tutorial

Creating Your First Blockchain With Java. Part1.

Creating Your First Blockchain With Java. Part1.

pineapple express, star trek, late night programming, Desperados ( with lime ) & looking beyond 22338618. Creating Your First Blockchain with Java. Part1. The aim of this tutorial series, is to help you build a picture of how one could develop blockchain technology. Create your first (very) basic blockchain. Implement a simple proof of work ( mining ) system. ( I will assume you have a basic understanding of Object Oriented Programming ) Its worth noting that this wont be a fully functioning, ready for production block chain. Instead this is a proof of concept implementation to help you understand what a blockchain is for future tutorials. You can support this and future tutorials:) We will be using Java but you should be able to follow along in any OOP language. Ill be using Eclipse but you can use any new fancy text editor ( though youll miss out on a lot of good bloat ). Dont worry if your eclipse looks different to mine. Ill be using a dark theme in eclipse because^ Optionally, you can grab GSON library by google (who are they???). This will allow us to turn an object into Json \o/. Its a super useful library that we will also be using further down the line for peer2peer stuff, but feel free to use an alternate method. In Eclipse create a (file > new > ) Java project. Ill call my Project noobchain and create a new Class by the same name (NoobChain). Dont be copying my project name now ( ) A blockchain is just a chain/list of blocks. Each block in the blockchain will have its own digital signature, contain digital signature of the previous block, and have some data ( this data could be transactions for example ). Each block doesnt just contain the hash of the block before it, but its own hash is in part, calculated from the previous hash. If the previous blocks data Continue reading >>

Create Your Own Bitcoin Wallet App Or Integrate Bitcoin As A Payment Option In Your Mobile App

Create Your Own Bitcoin Wallet App Or Integrate Bitcoin As A Payment Option In Your Mobile App

Create Your Own Bitcoin Wallet App or Integrate Bitcoin As a Payment Option in Your Mobile App So much has changed in the past ten years. Not so long ago, people used to transfer money from one bank to another bank using their laptops. Now, there is a completely new digital currency out there. Meet Blockchain the first virtual currency created in 2009 by an anonymous developer called Satoshi Nakamoto. However, what we will be discussing in this article is this: What is bitcoin wallet app. What are the benefits and opportunities of Bitcoin in mobile payments. Bitcoin Wallet App is a secure digital wallet used to send, receive, and store bitcoins. In order to use a cryptocurrency such as Bitcoin, a cryptocurrency wallet is needed. A cryptocurrency wallet is a software which stores public and private keys and interacts with different blockchain to allow users to send or receive digital currency. Just like Bitcoins, most coins have their own official wallet, while some also recommend third-party wallets. Benefits of Bitcoin Wallet App For Your Online Business One of the common questions online businesses ask today is that Why they should be interested in developing Bitcoin Wallet App of their own? Or, Why should they integrate Bitcoin as a mobile payment option in their business? The answer to these questions and the main benefits of Bitcoin Wallet App are as follow. Bitcoin Is The Most Simplest Form of Exchange: The nature of Bitcoin makes this digital currency a perfect solution for the cross-border transactions. Compared to other payment options, Bitcoin is the fastest among all. You can purchase bitcoin online for any other currency through an exchange. You can also mine bitcoins on your own. Although, it will require you to set a machine aside and have it run endlessl Continue reading >>

Android Example - [b4x] Blockchain Example - Create Your Own Cryptocurrency (part 1/2) | B4x Community - Android, Ios, Desktop, Server And Iot Programming Tools

Android Example - [b4x] Blockchain Example - Create Your Own Cryptocurrency (part 1/2) | B4x Community - Android, Ios, Desktop, Server And Iot Programming Tools

B4X Community - Android, iOS, desktop, server and IoT programming tools A digital ledger in which transactions made in bitcoin or another cryptocurrency are recorded chronologically and publicly. In more general terms, its a public database where new data are stored in a container called a block and are added to an immutable chain (hence blockchain) with data added in the past. In the case of Bitcoin and other cryptocurrencies, these data are groups of transactions. Blockchain technology has given rise to new, fully digital currencies like Bitcoin and Litecoin that arent issued or managed by a central authority. This brings new freedom to individuals who believe that todays banking systems are a scam or subject to failure. Blockchain has also revolutionized distributed computing in the form of technologies like Ethereum, which has introduced interesting concepts like smart contracts. Here's a B4X port of the first part of the example found in this page. The example is presented in B4J format, but the code should be compatible with any B4X product. Regarding part 2, I'll try the Python implementation this Saturday and once I feel comfortable with it, I'll try to port it into B4X. Meanwhile, here's the original article: Yes just read it. PoW difficiulty adjustmen is needed for an actual cryptocurrency , it wil not be enough obviosuly but it will be a good tutorial to learn how blockchain works ! I have inadvertently created a PoW (proof-of-work) algorithm 2 years ago, it was related to finding strings in random numbers, such as PI. If I recall, 5 character strings would take ~1-2 minutes to be found. Perhaps that could be a good starting point... I have inadvertently created a PoW (proof-of-work) algorithm 2 years ago, it was related to finding strings in random numbers, Continue reading >>

3 Ways To Set Up A Bitcoin Wallet (how To Guide)

3 Ways To Set Up A Bitcoin Wallet (how To Guide)

This guide will show you how to create and set up your first Bitcoin wallet (an “account”). But first: A “wallet” is basically the Bitcoin equivalent of a bank account. It allows you to receive bitcoins, store them, and then send them to others. There are two main types of wallets. A software wallet is one that you install on your own computer or mobile device. You are in complete control over the security of your coins, but they can sometimes be tricky to install and maintain. A web wallet or hosted wallet is one that is hosted by a third party. They are often much easier to use, but you have to trust the provider to maintain high levels of security to protect your coins. There are four main wallets that we recommend for beginners. Coinbase is a web wallet with a simple design and a number of very useful features that make it excellent for beginners. You can send and receive bitcoins via email and buy and sell bitcoins directly from Coinbase. A full-featured Android app enables access to all account functions on the go. Coinbase’s founders have a proven startup track record and have raised money from very prominent venture capitalists. This gives Coinbase a level of legitimacy unparalleled in the Bitcoin space. They are also one of the only large Bitcoin companies to never suffer a major hack. Click here to sign up. Electrum is a software wallet that enables you to set up a strong level of security very quickly. During the simple installation process, you are given a twelve word phrase that will allow you to recover all of your bitcoins in the event that your computer fails. Your wallet is also encrypted by default which helps protect your coins against hackers. Electrum is available for Windows, OSX, and Linux and is our recommended software wallet for begi Continue reading >>

Building Your First Blockchain App With Eris

Building Your First Blockchain App With Eris

Start an Eris keys service for authentication with: This command starts a service based on the keys service definition, these definitions are found inside the ~/.eris/services folder. Eris creates some by default for pre-defined application types (e.g. Tor , ipfs , and bigchaindb ), but you can also create your own . Now create some keys to allow particular users access to the service and application: Save the key for later use, replacing the key value with the key you just generated: eris keys export E0F4BA1E6D15503074239A663101547074889574 And use the following command to check what keys are available across your host machine and containers: If you want to read more about keys with Eris, then I recommend their key tutorial . Next, create a blockchain with a name (library_chain) and a type (simplechain): eris chains make library_chain --account-types=Root:2,Full:1 simplechain If you dig inside the hidden ~/.eris folder you will see the files generated from this command. Inside ~/.eris/chains/library_chain are a series of files: genesis.json: Tells eris how to instantiate a particular blockchain, providing the genesis state of the blockchain. accounts.csv and validators.csv: You can use two files later to create a new genesis.json if it gets lost. addresses.csv: Has the addresses and the names of the nodes. Now youre ready to instantiate the Blockchain: eris chains new library_chain --dir ~/.eris/chains/library_chain/library_chain_full_000 Check that the chain exists and is running: A smart contract is a popular blockchain-related term for an agreement that the blockchain will analyze transactions you send it. As a simple Eris related example, you will create a contract that sets a value and then gets it back again. Start by creating a folder for the application and mo Continue reading >>

How One Can Implement Blockchain For Android Development??

How One Can Implement Blockchain For Android Development??

I have seen many tutorial on blockchain but they all are some how assuming the learner to be web developer or kind of related field. Is there some stuff for android developer to learn so that we can use android studio with blockchain technology.? first you need to understand what blockchain is, it's just a distributed database Ayush Gupta Jan 28 at 4:52 Essentially you need to understand what is blockchain and how it works? the blockchain is distributed system where there is no central node to handle all transaction. All transaction handled by the miner. The blockchain is the combination of blocks. Each block contains the hash value of the previous block and current block. If previous block hash code changed, current block hash code has to change too. Please see code below to understand simple how blocks interconnected and importance of hash code. public class Block {private int previoushash;private String [] transactions;private int blockhash;public Block(int previoushash, String[] transactions) { this.previoushash = previoushash; this.transactions = transactions; Object[] contents = {Arrays.hashCode(transactions), previoushash}; this.blockhash = Arrays.hashCode(contents);}public int getPrevioushash() { return previoushash;}public String[] getTransactions() { return transactions;}public int getBlockhash() { return blockhash;} public class Main {ArrayList blockchain = new ArrayList<>();public static void main(String [] args) { /* hash= digital signature Each block contains: -list of transactions -previous hash -hash * */ System.out.println("Blochchain test initialized:\n"); String [] genesisTransactions = {"a send 10 bitcoin to elnur", "b send 3 bitcoin to elnur" , "c send 5 bitcoin to elnur"}; Block genesisBlock = new Block(0, genesisTransactions); System.out.println( Continue reading >>

3 Easy Steps: Creating Your New Bitcoin Wallet With Our Android App

3 Easy Steps: Creating Your New Bitcoin Wallet With Our Android App

Share your email with us to receive updates on Blockchain and the industry. Being able to send and receive bitcoins is only seconds away, after youve downloaded and installed Blockchains bitcoin wallet for Android. Did you know that you can also use our wallet on your Android tablet? In this guide, well show you how to create a new wallet using your Nexus 7 tablet, with tips included on how to ensure your wallet is safe and secure. The wallet creation process should be identical (or very close to it) for any Android device. If you havent yet, head over to the Google Play Store to download and install Blockchains Android Wallet . To create a new wallet, tap Open A New Wallet, as pictured below. Its time to create a pin! Make sure it is a unique string of four digits that you will remember. If youre afraid youll forget it, write it down and store it somewhere secure, like a safe! Its important you treat this pin number with the same significance youd treat the pin number for your debit or credit card. After you enter your pin a first time, youll then be asked to enter it again to confirm it. A checkbox will appear at the bottom of the screen, which says that you acknowledge and accept Blockchains terms of service. Put a checkmark in Accept and create wallet, and your wallet is almost ready! There are two additional security options available when setting up a new wallet. In the case that your phone becomes broken or lost, setting up a memorable password will allow you to access your bitcoins using our web wallet . We recommend creating a password that is a minimum of 16 characters and a combination of lowercase letters, uppercase letters, numbers and symbols. If youre worried you will forget it, write it down and store it somewhere safe, where only YOU have access. Anoth Continue reading >>

An Ethereum Api For Android App Developers

An Ethereum Api For Android App Developers

secure and innovative Android applications An Ethereum API for Android App Developers The time we first laid eyes upon the Ethereum project we were absolutely hyped because we imagined all the possibilities the Blockchain could hold for Android app development especially in terms of a fast and secure billing alternative for in-app purchases. As we got in touch with the technology and started working on Dapps ourselves we noticed not only the lack in Android support for Ethereum applications but the few existing Ethereum wallets were either scams or cross-platform apps not optimized for Android and with centralized nodes on 3rd-party servers. You might ask yourself now: Wait... but Ethereum on Android without connecting to a 3rd-party server? With a Full Node? That would take up way too much space on the device. That is correct. While there are ways to get a Full Node running directly on an Android device , it would take Gigabytes of space even in this early stage of the Ethereum Blockchain and until light clients are a thing we need alternatives. So we thought necessity is the mother of invention and started developing our own solution: Ethereum Android. Ethereum Android as a mobile portal toEthereum As Java developers we had a number of goals in mind: our solution should be a native Android application, offer a pleasant user-experience, and offer the user a simple way to connect to an Ethereum Full Node on a personal server. We wanted to build an Ethereum toolbox for Java developers, with all the tools developers are used to work with. Ethereum Android consists of three parts: the Server Node which is based on ethereumj , the wallet app which offers the similar functionality to the Mist Browser of Ethereum, and most importantly for developers: an API to access the Eth Continue reading >>

How To Make A Paper Bitcoin Wallet

How To Make A Paper Bitcoin Wallet

CoinDesk Launches 2017 Year in Review Opinion and Analysis Series One of the most popular options for keeping your bitcoins safe is something called a paper wallet. Here we explain how to transfer all those digital coins into a physical paper form using just a printer. Note that in this guide well be talking about bitcoin. However, the basic concepts apply to any other cryptocurrency; for example, litecoin. A bitcoin wallet consists of two keys. The one youll already likely be familiar with is the public key, which is your wallet address and is how other people send bitcoins to you. The other part of your bitcoin wallet is the private key. It is this that enables you to send bitcoins to other people. The combination of the recipients public key and your private key is what makes a cryptocurrency transaction possible. It is important to understand that, if anyone else obtains the private key of your wallet, they can withdraw your funds this is why its absolutely essential that nobody else discovers it. So, if you keep your coins in either an online wallet, or a hard-drive-based software wallet, you are vulnerable to attacks by hackers or malware that can log your keystrokes. Furthermore, a stolen PC or a hard-drive crash could also see you waving bye-bye to your digital treasure. Used with care, a paper wallet can protect you from these possibilities. A paper wallet is a document that contains copies of the public and private keys that make up a wallet. Often it will have QR codes, so that you can quickly scan them and add the keys into a software wallet to make a transaction. The benefit of a paper wallet is that the keys are not stored digitally anywhere, and are therefore not subject to cyber-attacks or hardware failures. The disadvantage of a paper wallet is that pa Continue reading >>

3 Best Bitcoin App Sdk For Ios And Android With Samples

3 Best Bitcoin App Sdk For Ios And Android With Samples

Bitcoin nowadays is not only a cryptocurrency or a digital payment system. Actually, thanks to its unique features bitcoin has become a real instrument for investment, saving and even earning more money. In this article we want to talk about 3 most popular bitcoin appSDK, that can help you to develop your own app. Thank their functionality you can create bitcoin wallet, a tool for investors, bitcoin game or any other app connected with this cryptocurrency. Also to check the popularity of analyzed SDKs our team of mobile app developers created three real examples of bitcoin wallets. See them below From 2.9 to 5.8 million people use cryptocurrency wallets in 2017, most of them work with bitcoins. Blockchain is regarded as the most popular bitcoin wallet in the world. Nowadays more than 14 million wallets are registered in BC worldwide. Moreover, Blockchain has a full stack of free APIs for developers, so we start our analysis with it. Supported platforms: Android, iOS, Windows, Mac OS, Linux Blockchain is very popular service. It supports many programming languages in form of libraries for its API (Python, Java, NET, Ruby, PHP, Node etc.). Receive Payments V2 API KEY: an easy way for websites to receive payments in bitcoins. This option is completely free and safe. It is ideal for business and personal using. Blockchain Wallet API KEY: full access to all functions of this service like creating a wallet, making payments, sending transactions, address management and so on. To receive any of the keys one must request API from BC. The application contains a name of person/organization, e-mail, and URL of the website or app. Post a project or a job and get estimations and offers from developers This process is supposed to exclude different ways of fraud or using keys for unfa Continue reading >>

Developing Apps For Blockchains

Developing Apps For Blockchains

Oops. I said I wasnt going to blog about Bitcoin for a while, but Coinbase recently took an official position stating that Ethereum is now at the forefront of the digital currency space . I can only agree with 99% of Freds writing: his analysis of the problems of Bitcoins developer community mirrors my own . But I noticed a small misconception in Freds post that I wanted to quickly correct, and thatll lead on nicely to a discussion of writing blockchain apps. He said: Bitcoins scripting language is intentionally restrictive. You might liken it to programming with an advanced graphing calculator functionality is limited. As a result, you can only do basic things. It is also hard to understand and use. Rather than most modern programming languages where the code is almost readable like a sentence, it looks like unintelligible machine code . As a result, it took Mike Hearn, a talented ex-Google developer, a whopping 8 months to write a first version of a fairly simple crowdfunding application . Fred is talking about Lighthouse, a P2P Bitcoin Kickstarter equivalent that uses the block chain: Its true that Bitcoins so-called Script is an assembly language rather than a scripting language as the name implies. But that isnt why it took eight months to write Lighthouse. It would have taken nearly as long even if it was built on top of Ethereum because the way Lighthouse uses scripting is trivial. Working with Bitcoin script was probably only about 2% of the total effort. If we as an industry misunderstand the pain points in developing decentralised financial applications then we wont be able to fix them. And in case youre wondering, yes Im still working on blockchain-type technology, this time at R3 on Corda, announced in this blog post , so Im still thinking about these thing Continue reading >>

Create Your Own Blockchain In 30 Minutes

Create Your Own Blockchain In 30 Minutes

s.saurel 27 January 2018 Create your own Blockchain in 30 minutes 2018-01-27T22:07:06+00:00 Java , Tutorials 3 Comments The Blockchain is a technological revolution at the heart of the success of Bitcoin and other crypto currencies. For some, the Blockchain is a revolution comparable to what the Internet was in its day. In this article, we propose you to create your own Blockchain in 30 minutes by using the Java programming language. It will allow you to better discover how the Blockchain works internally. Design and Create the Blocks for the Blockchain Creating the Blockchain by using the Blocks You can also discover this tutorial in video on YouTube: Design and Create the Blocks for the Blockchain First, we are going to design the Blocks for the Blockchain. Basically, a block contains the following information: Timestamp to store the creation date of the Block Data stored in the Block. For the Bitcoin and the other crypto currencies, data are transactions Hash of the current Block to ensure integrity of its content This gives us the following code for the properties of the Block : The hash of the blocks of our Blockchain will be calculated by relying on the cryptographic hashing algorithm SHA-256 which you will find all the details on wikipedia: . Luckily, the Java language SDK offers a standard implementation of this algorithm. It will not be necessary to code it ourselves. The cryptography algorithms offered by Java are recoverable via the MessageDigest class, which allows you to retrieve the instance of an algorithm by entering the name of the getInstance() method. It then remains to enter in parameter of the digest() method a textual representation of the blockss content to hash for getting the result of its hashing via the SHA-256 algorithm in the form of an arr Continue reading >>

Github - Blockchain/my-wallet-v3-android: Blockchain Android Wallet

Github - Blockchain/my-wallet-v3-android: Blockchain Android Wallet

Next-generation HD (BIP32, BIP39, BIP44) bitcoin, ethereum and bitcoin cash wallet. Install Android Studio: Run the bootstrap script from terminal via scripts/bootstrap.sh. This will install the Google Java code style as wellas the official Android Kotlin code style and remove any file header templates. The script may indicate that you needto restart Android Studio for it's changes to take effect. If there are build errors, in Android Studio go to Tools -> Android -> SDK Manager and install any available updates. All new code must be in Kotlin. We are using the official Kotlin style guide, which can be applied in Android Studio viaPreferences -> Editor -> Code Style -> Kotlin -> Set from -> Predefined style -> Kotlin Style Guide. It should benoted that this is not currently the default in Android Studio, so please configure this if you have recentlyreinstalled AS. Alternatively, simply run the bootstrap script and ktlint will configure your IDE for you. All code must be tested if possible, and must pass CI. Therefore it must introduce no new Lint errors, and must passKtlint. Before committing any new Kotlin code I could recommend formatting your files in Android Studio withCMD + ALT + L and running ./gradlew ktlint locally. You can if you so wish run ./gradlew ktlintFormat whichwill fix any style violations. Be aware that this may need to be run twice to apply all fixes as of 0.20. Unit tests for the project can be run via scripts/ci_unit_tests.sh. This also generates coverage reports. Continue reading >>

3 Best Bitcoin App Sdk For Ios And Android With Samples

3 Best Bitcoin App Sdk For Ios And Android With Samples

3 best bitcoin app SDK for iOS and Android with samples Bitcoin nowadays is not only a cryptocurrency or a digital payment system. Actually, thanks to its unique features bitcoin has become a real instrument for investment, saving and even earning more money. In this article we want to talk about 3 most popular bitcoin appSDK,thatcan help you to develop your own bitcoin app. Thank their functionality you can create bitcoin wallet, a tool for investors, bitcoin game or any other app connected with this cryptocurrency. Also to check the popularity of analyzed SDKs our team of mobile app developers created three real examples of bitcoin wallets. See them below From 2.9 to 5.8 million people use cryptocurrency wallets in 2017, most of them work with bitcoins. Blockchainis regarded as the most popular bitcoin wallet in the world. Nowadays more than 14 million wallets are registered inBCworldwide. Moreover, Blockchain has a full stack of free APIs for developers, so we start our analysis with it. Supported platforms: Android, iOS, Windows, Mac OS, Linux Blockchainis very popular service. It supports many programming languages in form of libraries for its API (Python, Java, NET, Ruby, PHP, Node etc.). Receive Payments V2API KEY: an easy way for websites to receivepaymentsin bitcoins. This option is completely free and safe. It is ideal for business and personal using. Blockchain WalletAPIKEY: full access to all functions of this service like creating a wallet, making payments, sending transactions, address management and so on. To receive any of the keys one must request API fromBC.The application contains a name of person/organization, e-mail, and URL of the website or app. This process is supposed to exclude different ways of fraud or using keys for unfair purposes. So that Continue reading >>

Chainhero - Tutorial: How To Build Your First App With Blockchain?

Chainhero - Tutorial: How To Build Your First App With Blockchain?

This tutorial wont explain in detail how Hyperledger Fabric works. I will just give some tips to understand the general behavior of the framework. If you want to get a full explanation of the tool, go to the official documentation there is a lot of work there that explains what kind of blockchain, Hyperledger Fabric is. This tutorial has been made on Ubuntu 16.04, but the Hyperledger Fabric framework is compatible with Mac OS X, Windows and other Linux distributions. We will use the Go language to design a first application, because the Hyperledger Fabric has been built also in Go and the Fabric SDK Go is really simple to use. In addition, the chaincode (smart contract) can be written in Go too. So the full-stack will be only in Go! There are other SDK if you want to, like for NodeJS, Java or Python. Hyperledger Fabric uses Docker to easily deploy a blockchain network. In addition, in the v1.0, some component (peers) also deploys docker containers to separate data (channel). So make sure that the platform supports this kind of virtualization. Hyperledger Fabric is a platform for distributed ledger solutions underpinned by a modular architecture delivering high degrees of confidentiality, resiliency, flexibility and scalability. It is designed to support pluggable implementations of different components and accommodate the complexity and intricacies that exist across the economic ecosystem. See the full explaination from the official documentation, in the introduction part: Hyperledger Fabric Blockchain This tutorial was made on Ubuntu 16.04, but there is some help for make the installation in Windows, Mac OS X and other Linux distributions. The required version for docker is 1.12 or greater, this version is already available in the package manager on Ubuntu. Just insta Continue reading >>

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