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Ethereum Development Tutorial

Ethereum Development Tutorial

The purpose of this page is to serve as an introduction to the basics of Ethereum that you will need to understand from a development standpoint, in order to produce contracts and decentralized applications. For a general introduction to Ethereum, see the white paper , and for a full technical spec see the yellow papers, although those are not prerequisites for this page; that is to say, this page is meant as an alternative introduction to Ethereum specifically targeted towards application developers. Ethereum is a platform that is intended to allow people to easily write decentralized applications (apps) using blockchain technology. A decentralized application is an application which serves some specific purpose to its users, but which has the important property that the application itself does not depend on any specific party existing. Rather than serving as a front-end for selling or providing a specific party's services, a app is a tool for people and organizations on different sides of an interaction used to come together without any centralized intermediary. Even necessary "intermediary" functions that are typically the domain of centralized providers, such as filtering, identity management, escrow and dispute resolution, are either handled directly by the network or left open for anyone to participate, using tools like internal token systems and reputation systems to ensure that users get access to high-quality services. Early examples of apps include BitTorrent for file sharing and Bitcoin for currency. Ethereum takes the primary developments used by BitTorrent and Bitcoin, the peer to peer network and the blockchain, and generalizes them in order to allow developers to use these technologies for any purpose. The Ethereum blockchain can be alternately described Continue reading >>

Whisper Poc 2 Protocol Spec

Whisper Poc 2 Protocol Spec

This page, in addition to the Whisper Wire Specification, details the full Whisper protocol for the first proof-of-concept and sets the vision for the final design. It evolve alongside the Whisper protocol as the prototype is refined. From it you should be able to develop compliant Whisper implementations. This document is intended to give only the base specification. Many of the aspects leading to an implementation of Whisper are game theoretic and best not prescribed in the specification, but rather left to individual implementation teams to determine for themselves. Whisper combines aspects of both DHTs and datagram messaging systems (e.g. UDP). As such it may be likened and compared to both, not dissimilar to the matter/energy duality (apologies to physicists for the blatant abuse of a fundamental and beautiful natural principle). Whisper is a pure identity-based messaging system. Whisper provides a low-level (non-application-specific) but easily-accessible API without being based upon or prejudiced by the low-level hardware attributes and characteristics, particularly the notion of singular endpoints. Alternatively, Whisper may be likened to a DHT with a per-entry configurable TTL and conventions for the signing and encryption of values. In this sense, Whisper provides the ability to have multiply-indexable, non-unique entries (i.e. the same entry having multiple keys, some or all of which may be the same as other entries). As such, Whisper is not a typical communications system. It is not designed to replace or substitute TCP/IP, UDP, HTTP or any other traditional protocols; it is not designed to provide a connection oriented system, nor for simply delivering data betwixt a pair of specific network endpoints; it does not have a primary goal of maximising bandwidt Continue reading >>

Signal Protocol - Wikipedia

Signal Protocol - Wikipedia

This article is incomplete. This is because the article is currently missing information about how the Signal Protocol functions. A detailed description can be found in Cohn-Gordon et al. 2016 . Please help to improve it, or discuss the issue on the talk page . The Signal Protocol (formerly known as the TextSecure Protocol) is a non- federated cryptographic protocol that can be used to provide end-to-end encryption for voice calls, video calls, [3] and instant messaging conversations. [2] The protocol was developed by Open Whisper Systems in 2013 [2] and was first introduced in the open source TextSecure app, which later became Signal . It has since been implemented into closed source applications, such as WhatsApp , which is said to encrypt the conversations of "more than a billion people worldwide". [4] Facebook Messenger also say they offer the protocol for optional "secret conversations", as does Google Allo for its "incognito mode". The protocol combines the Double Ratchet Algorithm , prekeys, and a triple DiffieHellman (3-DH) handshake, [5] and uses Curve25519 , AES-256 and HMAC-SHA256 as primitives . [6] The Signal Protocol's development was started by Trevor Perrin and Moxie Marlinspike (Open Whisper Systems) in 2013. The first version of the protocol, TextSecure v1, was based on Off-the-Record Messaging (OTR). [7] [8] On 24 February 2014, Open Whisper Systems introduced TextSecure v2, [9] which migrated to the Axolotl Ratchet. [7] [10] The design of the Axolotl Ratchet is based on the ephemeral key exchange that was introduced by OTR and combines it with a symmetric-key ratchet modeled after the Silent Circle Instant Messaging Protocol (SCIMP). [1] It brought about support for asynchronous communication ("offline messages") as its major new feature, as well as Continue reading >>

Go Ethereum Mobile

Go Ethereum Mobile

It is a fast, cheap and low But theres still a long way to go. However, in an article on the Light client in the Ethereum blog, there are some things that DApp developers should be aware of about lightness. 7 Apr 2017 To provide Ethereum integration for your mobile applications, the very first thing you should be interested in doing is account management. Ethereum Wallet has integrated with ShapeShift, which makes it easy to accept Bitcoin and other altcoin payments Dec 07, 2017 The rise of cryptocurrencies was tested Thursday as the blockchain-based Ethereum network continued to be overrun by a surge in the trading of virtual kittens. Our prime objective is to build a mobile first network for Ethereum ERC20 tokens thats off chain. node, Package node sets up multi-protocol Ethereum nodes. Fatal(err). we must wait on the official Light Client for the mobile devices. The three best Ethereum mining pool options are You really cant go wrong joining any of the a mobile app that automatically turns your daily spending Read our Complete Beginner's Guide on How to Buy Ethereum Instantly using a on the go. com/ethereum/go-ethereum/wiki/Mobile-Clients:-Libraries Go Ethereum is now easier to integrate with mobile platforms. Ethereum (ETH) Price updated in real-time every minute 5 exchanges 7 ETH currency pairs No advertising More news for Go Ethereum Mobile Planning to make some modifications to the go-ethereum mobile code,so inorder to do that need to use "make android" command which will create the geth. Previously, ease of and mobile app. } build. Steps: Go to HOME SEND. The mobile version of the software allows traders to execute Whenever investors decide to go with an automated When will Ethereum mining end? The time bomb was originally planned to go off at the end of 2017 b Continue reading >>

David Burela | Burela's House-o-blog

David Burela | Burela's House-o-blog

David Burela blockchain , Community Report blockchain , Community Report , ethereum I was proud to be a sponsor, trainer and mentor at the Smart Cities Blockchain Hackathon SmartCitiesHack Melbourne brings together the brightest minds to develop innovative solutions, utilising IOT, Blockchain and Big Data to introduce smart technology to solve real world problems, in one of Australias largest cities. An impressive aspect of the hack is that there were 2 teams from a girls high school, one from a college, and one solo university student. It was great to see younger people getting involved and solving problems from their own unique perspective. The final demos that interested me the most were: And of course there was lots and lots of food sponsored by Microsoft A few guest speakers presented at the beginning of the day to help give insights into what type of challenges cities are facing. One of them was the CIO of the city of Palo Alto Cities of the future need to focus on 3 key things: Liveability, workability & sustainability. 6% of Australias GDP goes through Melbourne How do you prepare a city for autonomous vehicles. Digital identity. Who owns it, who can use it. How can gov policy keep up (some industries will be dead before legislation even comes in) We have such a massive influx of people moving into the cities. If we think traffic congestion is bad now, wait until the future! Thinks the issue is climate change trumps any other issue. Users dont want to deal with governments in giant waiting queues at centrelink. They want to just pull out a smartphone app and renew their license. Decentralised way to list rentable spaces e.g. conference rooms, lecture theatres. Can book it using blockchain, get a QR code, can enter the room. Do it peer to per so that you can red Continue reading >>

Whisper Overview Ethereum/wiki Wiki Github

Whisper Overview Ethereum/wiki Wiki Github

var shh = web3.shh;var appName = "My silly app!";var myName = "Gav Would";var myIdentity = shh.newIdentity();shh.post({ "from": myIdentity, "topics": [ web3.fromAscii(appName) ], "payload": [ web3.fromAscii(myName), web3.fromAscii("What is your name?") ], "ttl": 100, "priority": 1000});var replyWatch = shh.watch({ "topics": [ web3.fromAscii(appName), myIdentity ], "to": myIdentity});// could be "topic": [ web3.fromAscii(appName), null ] if we wanted to filter all such// messages for this app, but we'd be unable to read the contents.replyWatch.arrived(function(m){ // new message m console.log("Reply from " + web3.toAscii(m.payload) + " whose address is " + m.from);});var broadcastWatch = shh.watch({ "topic": [ web3.fromAscii(appName) ] });broadcastWatch.arrived(function(m){ if (m.from != myIdentity) { // new message m: someone's asking for our name. Let's tell them. var broadcaster = web3.toAscii(m.payload).substr(0, 32); console.log("Broadcast from " + broadcaster + "; replying to tell them our name."); shh.post({ "from": eth.key, "to": m.from, "topics": [ eth.fromAscii(appName), m.from ], "payload": [ eth.fromAscii(myName) ], "ttl": 2, "priority": 500 }); }}); post takes a JSON object containing four key parameters: shh.post({ "topics": t, "payload": p, "ttl": ttl, "workToProve": work }); topic, provided as either a list of, or a single, arbitrary data items that are used to encode the abstract topic of this message, later used to filter messages for those that are of interest; payload, provided similarly to topic but left as an unformatted byte array provides the data to be sent. ttl is a time for the message to live on the network, specified in seconds. This defaults to 50. work is the amount of priority you want the packet to have on the network. It is specified in Continue reading >>

Roundup Q2 - Ethereum Blog

Roundup Q2 - Ethereum Blog

Thanks to all the developers and team leads who contributed to the sections on their projects In the last month and a half, the Ethereum network went through a rapid growth in usage, to the point that it now processes as many transactions per second as Bitcoin. To accommodate the increased load, which has on a few occasions reached the networks full capacity for hours at a time, the community independently came together and miners voted to increase the gas limit to 6.7 million . We at the Foundation have been rapidly putting additional resources toward increasing the efficiency of the network, alongside planning longer-term changes that will greatly increase the networks scalability. The Ethereum research team came together in Singapore and discussed various topics to do with Casper, sharding and Ethereum protocol economics. A prototype of Casper the Friendly Finality Gadget/Fork Choice Rule in Python is close to being finished: A new version of the Mauve Paper is underway and reaching early draft stage, though possibly in the form of multiple papers discussing specific considerations and categories of attacks The pyethereum client has seen a substantial revamp, and version 2.0 has been released. See for download; in Ubuntu you can also do sudo pip install ethereum. Additionally, we have implemented experimental versions of: State tree pruning (reducing disk consumption by over 80%): On-disk state cache (makes state reads require one database read instead of O(log(n)): Metropolis testing is rapidly moving forward. We are actively seeking additional help with finishing testing. See: Guide on helping with the Metropolis testing effort: Public support channel for those who want to help with Metropolis testing: Guide written by Yoichi: We have started a substantial cross-c Continue reading >>

How To Whisper Ethereum/go-ethereum Wiki Github

How To Whisper Ethereum/go-ethereum Wiki Github

Whisper is a pure identity-based messaging system. Whisper provides a low-level (non-application-specific) but easily-accessible API without being based upon or prejudiced by the low-level hardware attributes and characteristics, particularly the notion of singular endpoints. This tutorial assumes you've read p2p 101 . If you haven't read it I suggest you read it. This tutorial will guide you to setting up a full p2p server with whisper capabilities. Let's quickly cover some of whisper's basic functionality and discuss it in greater detail later. The notion of envelopes and messages in whisper is somewhat blurred. An application shouldn't ever need to know the difference between the two and should only care about the information it's interested in. Therefor whisper comes with a subscribing mechanism which allows you watch/listen for specific whisper messages (e.g., to you, with a specific topic, etc). whisper.Watch(Filter{ From: myFriendsPubKey, Fn: func(msg *whisper.Message) { /* ... */ },}) Whenever you want to send message over the whisper network you need to prove to network you've done some significant work for sealing the message (such is the cost for sending messages) and thus the more work you put in to sealing the message the higher the priority the message will have when propagating it over the network. Whisper's Proof of Work consists of a simple SHA3 algorithm in which we try to find the smallest number within a given time frame. Giving the algorithm more time will result in a smaller number which means the message has a higher priority in the network. Messages are also sealed with a Time To Live. Whisper peers will automatically flush out messages which have exceeded their time to live (with a maximum up to 2 days). Additionally messages may also contain a Continue reading >>

Whisper Ethereum/wiki Wiki Github

Whisper Ethereum/wiki Wiki Github

In a nutshell whisper is a communication protocol for DApps to communicate with each other. DApps that need to publish small amounts of information to each other and have the publication last some substantial amount of time. For example, a currency exchange DApp may use it to record an offer to sell some currency at a particular rate on an exchange. In this case, it may last anything between tens of minutes and days. The offer wouldn't be binding, merely a hint to get a potential deal started. DApps that need to signal to each other in order to ultimately collaborate on a transaction. For example, a currency exchange DApp may use it to coordinate an offer prior to creating one (or two, depending on how the exchange is structured) transactions on the exchange. DApps that need to provide non-real-time hinting or general communications between each other. E.g. a small chat-room app. DApps that need to provide dark (plausible denial over perfect network traffic analysis) comms to two correspondents that know nothing of each other but a hash. This could be a DApp for a whistleblower to communicate to a known journalist exchange some small amount of verifiable material and arrange between themselves for some other protocol (Swarm, perhaps) to handle the bulk transfer. In general, think transactions, but without the eventual archival, any necessity of being bound to what is said or automated execution & state change. Low-latency, 1-1 or 1-N signalling messages. High latency, high TTL 1-* publication messages. Messages less than 64K bytes, typically around 256 bytes. UDP: Similar in API-level, native multicasting. No TTL, security or privacy safeguards. 0MQ : A distributed messaging system, no inherent privacy safeguards. Bitmessage : Similar in the basic approach of P2P netwo Continue reading >>

Text Publishing Technologies For Ethereum Dapps

Text Publishing Technologies For Ethereum Dapps

Text publishing technologies for Ethereum dapps Submitted by jbrown on Mon, 01/18/2016 - 11:33 Building something like a Reddit or Twitter dapp (distributed app) on Ethereum is certainly an attractive idea, but the obvious question is "where do the messages get stored?" If an autonomous Git or Wikipedia were built on Ethereum the storage requirements would be even greater. As outlined in a previous post , compressing text before storing it is a very good idea, especially if the storage medium is expensive. There are many different decentralized technologies that can be used to store and share these blobs . A key factor is permanence. I have analysed the properties of some of these technologies, ordered from most to least permanent: When a smart contract executes a transaction it can modify its state . The latest version of every contract's state is always available. Most expensive. Each non-zero byte in transaction payload costs 68 gas . That's 2,176 gas for 32 bytes. The smart contract must then store the blob in its state. Using a new 32-byte state slot costs 20,000 gas. Overwriting an existing slot costs 5,000. Zeroing an existing slot gives a refund of 15,000. There is an on-going discussion about charging rent for state storage. 0.050589 USD / kB at time of writing. This would be expected to go down in the long term as Ethereum becomes more efficient. It should be noted that if an external storage system is used, an identifier would probably need to be stored in contract state anyway. This should be taken into account when comparing costs. A contract can potentially read or write a blob stored in state, although reading may not be useful if the blob is compressed or encrypted. Autonomous bots could be written to respond to and/or create posts. 4kB with current blo Continue reading >>

Announcing Parity 1.8

Announcing Parity 1.8

Winter may be coming but the moment youve all been waiting for has finally arrived: Parity Tech is excited to announce the release of the BIGGER and BETTER 1.8.0. This release will see light client improvements: Proof-of-Authority chain compatibility, even with dynamic authority sets, and also feature compatibility with the Whisper v6 wire protocol. We're thrilled to say that we now officially support the Trezor hardware wallet. When plugging in your Trezor device you are presented with a Pin Matrix to unlock your device. Once unlocked, the hardware wallet will be added as an account in the Parity Wallet. Furthermore, we recently announced the launch of the Parity ICO Passport Service (PICOPS) . PICOPS is a new Know Your Customer (KYC) service that enables users to certify a single Ethereum address with their identity. In order to get an address certified one needs to pay a small fee and upload a picture of ones passport (optionally national ID or driver's licence in some countries). The document is checked against digital tampering, databases of stolen documents and sanction watchlists. Owners of certified addresses can then participate in ICOs that partner with PICOPS. Lastly, weve undertaken a major refactor of Paritys internals designed to completely decouple consensus logic from transaction and block verification logic. This allows us to reason not only about pluggable consensus, but also pluggable state transition systems. Moving onwards, this flexibility will enable us to unite the implementations of many different kinds of chains under a common interface. Light-client compatibility for PoA networks under dynamic authority sets. Secure Dapp certification & reputation system with sybil-resistance through PICOPS. You can use the new vouching mechanism to vouch for Continue reading >>

Dapps Not Need To Wait For Blocktime

Dapps Not Need To Wait For Blocktime

Ethereum-based slot machine platform for both MAKE&PLAY Blockchains are slow. So slow that almost any application that requires real time response merely cannot be implemented on-chain. Ethereum Foundation has estimated the blocktime to consistently increase throughout the rest of the year, from 20 seconds at the time of writing to 45 seconds on November. This surely will lay serious difficulties on real time DApps. There comes the question, do we really need to wait for the whole blocktime for every transactions in DApps? As Betteridges law says, we DONT. Though the actual modification of status on the smart contracts surely needs block confirmations including ETH balances, the results of the transactions and the modified status can be computed in advance to block confirmation if given the original source codes of the contract and the legitimate inputs to it. Any application which doesnt hesitate to reveal the non-compiled solidity codes of the contracts open in the public, enables its terminal clients to infer the results of the on-chain interactions, thus NOT having to wait for the on-chain confirmation. SlotNSlot project very well fits the condition. The smart contract codes will all be open public in Github repositories, and the same logics will be implemented in the client sides. Players on slot machines, or the bankers watching them play, need not to wait for the blockchain to give back the result of every round to proceed the games, as long as theyre confident that the transactions they see in the pending list will definitely be mined into the chain. In designing a two-party commit&reveal random number generation(RNG) for our service, our initial idea was to utilize Whisper, the p2p messaging protocol on Ethereum, to reduce the number of transactions required f Continue reading >>

Tools And Technologies In The Ethereum Ecosystem

Tools And Technologies In The Ethereum Ecosystem

Techie, Foodie, Traveler, Tinkering with Blockchain at www.zastrin.com Tools and Technologies in the Ethereum Ecosystem If you are a developer new to Ethereum/blockchain, it is possible you are overwhelmed (at least I was) trying to understand all the tools and technologies in the Ethereum ecosystem. So I decided to briefly describe the various components you come across frequently while starting to learn Ethereum. Hopefully this will help you get a big picture of the Ethereum ecosystem and how all the pieces fit together. Ethereum is a smart contract blockchain on which you can build decentralized applications (called smart contracts). If you are a technologist, this white paper is worth reading: . If you have built web applications before, I wrote a post comparing Ethereum blockchain and web application architecture which might help understand Ethereum at a high level. Geth is the official client software provided by the Ethereum Foundation . It is written in the Go programming language. This software packages a few components which is worth understanding: When you start this client daemon, it connects to other clients (also called nodes) in the network and downloads a copy of the blockchain. It will constantly communicate with other nodes to keep its copy of the blockchain up to date. It also has the ability to mine blocks and add transactions to the blockchain, validate the transactions in the block and also execute the transactions. It also acts as a server by exposing APIs you can interact with through RPC. This is a command line tool which lets you connect to your running node and perform various actions like create and manage accounts, query the blockchain, sign and submit transactions to the blockchain and so on. This is a desktop application used to communica Continue reading >>

Dapps Ethereum Homestead 0.1 Documentation

Dapps Ethereum Homestead 0.1 Documentation

Swarm is a distributed storage platform and content distribution service, a native base layer service of the Ethereum web 3 stack. The primary objective of Swarm is to provide a sufficiently decentralized and redundant store of Ethereums public record, in particular to store and distribute dapp code and data as well as block chain data. From an economic point of view, it allows participants to efficiently pool their storage and bandwidth resources in order to provide the aforementioned services to all participants. From the end users perspective, Swarm is not that different from WWW, except that uploads are not to a specific server. The objective is to peer-to-peer storage and serving solution that is DDOS-resistant, zero-downtime, fault-tolerant and censorship-resistant as well as self-sustaining due to a built-in incentive system which uses peer to peer accounting and allows trading resources for payment. Swarm is designed to deeply integrate with the devp2p multiprotocol network layer of Ethereum as well as with the Ethereum blockchain for domain name resolution, service payments and content availability insurance. Continue reading >>

Whisperv2 - Godoc

Whisperv2 - Godoc

( ) Whisper combines aspects of both DHTs and datagram messaging systems (e.g. UDP).As such it may be likened and compared to both, not dissimilar to thematter/energy duality (apologies to physicists for the blatant abuse of afundamental and beautiful natural principle). Whisper is a pure identity-based messaging system. Whisper provides a low-level(non-application-specific) but easily-accessible API without being based uponor prejudiced by the low-level hardware attributes and characteristics,particularly the notion of singular endpoints. func NewTopics(data ...[] byte ) [] Topic NewTopics creates a list of topics from a list of binary data elements, byiteratively calling NewTopic on each of them. func NewTopicsFromStrings(data ... string ) [] Topic NewTopicsFromStrings creates a list of topics from a list of textual dataelements, by iteratively calling NewTopicFromString on each of them. type Envelope struct { Expiry uint32 // Whisper protocol specifies int32, really should be int64 TTL uint32 // ^^^^^^ Topics [] Topic Data [] byte Nonce uint32 // contains filtered or unexported fields} Envelope represents a clear-text data packet to transmit through the Whispernetwork. Its contents may or may not be encrypted and signed. func NewEnvelope(ttl time . Duration , topics [] Topic , msg * Message ) * Envelope NewEnvelope wraps a Whisper message with expiration and destination dataincluded into an envelope for network forwarding. func (self * Envelope ) Hash() common . Hash Hash returns the SHA3 hash of the envelope, calculating it if not yet done. func (self * Envelope ) Open(key * ecdsa . PrivateKey ) (msg * Message , err error ) Open extracts the message contained within a potentially encrypted envelope. func (self * Envelope ) Seal(pow time . Duration ) Seal closes the Continue reading >>

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