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Questions tagged [blockchain]

The Ethereum blockchain is a distributed database based on the Ethereum whitepaper specification and stores both the full transaction list and the most recent state.

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How to set up a Private network and connect peers in geth?

I am trying to setup a private network and trying to connect peers. Currently I'm trying it on my laptop and desktop (both of them are connected to different internet). I run the below command in ...
0
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1answer
12 views

timed commitment using ethereum blockchain

I read this paper: https://eprint.iacr.org/2013/784.pdf that introduces the idea of Bitcoin-based time commitment scheme. In which if the commiter does not open his commitment before a specific time ...
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1answer
149 views

How can I show on web3j a list of all the instructors added on my blockchain?

I need to show on an html a list of all the instructors that are set up on the list pragma solidity ^0.4.18; contract Owned { address owner; function Owned() public { owner = msg.sender; } ...
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1answer
140 views

State tree diagram with real world ethereum transaction

Newbee here. Just getting used to StackExchange interface and protocol. Apologies up front for any feeling of misgiving. Would anyone be able to provide an ethereum state trie diagram depicting how ...
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1answer
29 views

Execute smart contract only if the wallet contains some tokens [on hold]

i created an erc20 token and i'm trying to create a smart contract that stores some informations in a blockchain just if the wallet contain my tokens. How can i do this? Have i to work on the token ...
0
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1answer
23 views

Transferring funds from a contract to an account using adresses

I had been trying for a long to transfer the complete fund with one of my contracts to a specific account. But nothing seems to be working. pragma solidity >= 0.4.22; contract reg{ address ...
0
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1answer
18 views

How do we extract the content of a hash manifest generated by swarm after a download?

As far I know, whenever we upload a file or a directory using: swarm up File we get back a hash that is the manifest containing the uploaded file. However, I am not sure I do understand how to ...
0
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1answer
158 views

Posting data from raspberry pi on blockchain and retrieving it back

I am new to blockchain technology. I just want to know if it is possible to post the data from raspberry pi on blockchain (ethereum) and retrieve the posted data for viewing. My question is if its ...
3
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1answer
147 views

What is the shared nibble of this extension node?

I have an extension node here: Key: 000b17906abb9f83c5e190bc3d0bed212e66bf44d99997c53c2071e1413194b6 Value: [ 3866a6d45a815576000da23c1a017179233e9d6437806aef7c2264588739d0, ...
0
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1answer
25 views

How Ethereum stores its data in the blockchain [duplicate]

I am new to ethereum and the blockchain, but I am wondering about blockchain databases. Mainly I am wondering how exactly the database data and the blockchain merge. For instance, in a database you ...
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2answers
195 views

web3 (then property) in ethereum node

Would you please help: When I run the below command in my nodejs console I get the below error: (I am using web3 0.20.0) on Windows 10 web3.eth.getAccounts().then(list => {accts = list}) ...
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1answer
7k views

Send ether to contract address in web3.js

I want to send ether to this contract's contribute function using web3.js I'm trying below code for the same but this doesn't work for me. var AbiOfContract = 'abi_code'; var contractAddress = "...
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3answers
18k views

What is the cost to store 1KB, 10KB, 100KB worth of data into the ethereum blockchain?

Whatever is stored in the blockchain is immutable which means I can fetch this data back in the future. As of today (2016-feb), How does one store a 1kb, 10kb, or 100kb or arbitary data/text in the ...
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1answer
204 views

Miner and Validator, who can validate a contract?

I am still confused with the process from creation to validation of transaction or contract verification. Actually the terminology makes me confused such as voter, validation, miner, honest node, ...
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0answers
19 views

What is the current state of integrating sharding into ethereum? [closed]

I recently found articles about the topic 'sharding' and how it could help scale ethereum to make it faster in the end. Can anyone tell me what is the current state of integrating sharding into the ...
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1answer
233 views

How to make API calls from a .NET Application to an Ethereum Private Network

I'm starting on blockchain development and I have a question: I was wondering if it is possible to make RPC calls to a private ethereum network (handling user private keys is not a problem in our ...
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1answer
16 views

Is there multiple chains of block in ethereum network?

Since blockchain is a chain of blocks, In ethereum, 1. is there only one chain of blocks 2. are there multiple chains of blocks.
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1answer
19 views

How does number of miners impact in processing the business logic(smart contract) in Blockchains

Does a number of validating devices/miners have an impact on processing business logic? If I understand correctly, as the number of validating devices increases, the time it takes to reach the ...
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1answer
183 views

How to connect IPC and RPC to transact fake ethers?

I have setup 2 nodes, 1 on testRPC and the other on geth(using cmd and mist). How to sync both the nodes so that I can write a crowdfunding smartcontract for the accounts in both the private nodes to ...
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2answers
25 views

Saving the actual data vs. hash of the data - which one is better?

I am new to etheruem, I would like to create a smart contract for keeping document data. From 2 designs below, can I know the pro and con of each one, please? put the array of raw JSON data to the ...
0
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1answer
178 views

How a smart contract works and when is activated?

I am trying to understand how a smart contracts works and what are the steps from requesting to receiving some amount of coin (let's say ethereum). I have some questions.. When a smart contract is ...
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0answers
25 views

What filesystem should I use for geth and leveldb?

I used old LGA775 machine for running geth node. Its mobo has older sata 3gb/s (benchmark showed that ssd bottlenecked there) and only 4gb of DDR2, with windows installed. So syncing is a real pain ...
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1answer
202 views

oraclize calling a REST API

I am trying to call a third party REST API that I developed using spring boot, and I want to call a function(param1,param2) in the API from the oracle using the oraclize_query() (POST request), but I ...
5
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2answers
719 views

Is it recommended to run Ethereum supernodes?

In the early days of bitcoin there was a demand for system administrators who were able to run supernodes to support the network with stable nodes and high bandwidth. Litecoin is still recommending ...
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2answers
218 views

Unlocking Ethereum wallet using Geth JSON-RPC

When I use ETH with JSON-RPC I have error "message": "authentication needed: password or unlock» and If I manually unlock I have other error "message": "insufficient funds for gas * price + value" Any ...
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3answers
43 views

How to store private data on blockchain to be readable from a contract?

I'm writting DApp on Ethereum (Solidity) and I need to find a solution how to store a private data on blockchain, when I also need to proceed them somehow. If it is only about storing, I can use some ...
0
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1answer
13 views

Is it possible to provide some manual data to create private key for the ethereum account?

We were trying to provide some manual data to create the private key if I want to create a new ethereum account using this private key.
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1answer
213 views

How to generate a seed for multi-currency wallet?

I am developing a mobile wallet that supports multiple currencies (including Ethereum). As of now, it only supports one currency. The RPC wallet creation function for this currency returns a private ...
0
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1answer
221 views

Where does geth store data except for the AppData\Roaming\Ethereum folder?

The AppData\Roaming\Ethereum folder on my computer weighs 5GB, but geth has reduced my disk space by a lot more than 5GB. Where else does it store data?
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1answer
22 views

Questions about blockchain

I am a newbie with blockchain and I have a few questions please, I've already googled but I have misunderstood some points: How data is stored in the block in blockchain? in bit format, text or other?...
2
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1answer
31 views

How an Ethereum Node stores data?

How an Ethereum client stores the blockchain data in the disk? I know two of the major Ethereum clients is go-ethereum and parity, so I'm also asking if they store data in a different way or if there ...
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3answers
190 views

Mist / Ethereum Wallet question

I bought a very small amount of ETH on coinbase just to try it, and I wanted to create my own wallet to get it out. However, I've been trying to get Mist working for 3 days and it is always stuck on ...
0
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1answer
30 views

How to return the struct data

How to return the struct data struct Transaction { address from; address payable to; uint amount; } I am returning like this function transactionDetails() external view returns(...
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1answer
40 views

how to validate and execute an ethereum transaction

I'm confused about how to validate a transaction in Ethereum. In fact, according to my simple knowledge, I know that the transaction row is signed and then the signature of the transaction is ...
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3answers
210 views

Does Using Infura Breaks Decentralization?

Decentralized applications have a philosophy: they are immutable,secure and trustless applications. You can connect to Blockchain and be sure about that features. Infura is a great tool when ...
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1answer
205 views

Multiple addresses initialization in constructor function

Usually we have one address initialization in constructor function. And that address becomes owner of the contract. While studying erc721 token and going through several examples online i found ceo ...
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1answer
932 views

Find out latest block hash in Ethereum using JSON-RPC

I am developing an ethereum block explorer in PHP and have established an JSON-RPC communication with my server geth node successfully. Nevertheless, I am kind of stuck when trying to find out the ...
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1answer
70 views

Does the ethereum ecosystem exist out of one or multiple blockchains?

Most of my knowledge is based on BTC which doesn't have the concept of (ERC-20) 'Tokens' so I have a question related to that: Does the Ethereum 'ecosystem' with its hundreds or even thousands of ...
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2answers
310 views

Smart Contract - Update implementation using a Relay with delegateCall

I know that smart contracts are supposed to be immutable and that's the whole point, but to expect someone to implement a logic that never changes (no upgrade or no bugs) from day 1 is also ...
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0answers
131 views

How to get multiple values in single Oraclize query? without JSON Parsing

I am developing a smart contract. I already made my own Token. so I wanna transfer my Tokens to my friends. But I wanna handle it easily, so I made XML what can be loaded on Internet to use ...
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2answers
298 views

Geth windows console - get Transaction and balance problem [duplicate]

I have setup a geth client in windows. By using below command I am able to run geth. geth --rinkeby --verbosity "0" console I created an account then pasted my public key on twitter to get funded ...
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2answers
482 views

Ethereum wallet/Geth incredibly slow to sync, help?

So I've noticed some people having the issue similar to mine, entitling their post as "very VERY slow to sync" and other variations of that, however they're complaining at around 100 blocks every ...
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1answer
19 views

Can anyone please help me how can I start with blockchain testing,Deploy application and testing app [closed]

I am completely new to blockchain testing.Can someone please help me with how can I start with blockchain testing and procedure from where I should start and material for the same if possible.
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2answers
431 views

How to connect peers which are on different computers in geth on private network?

I am trying to setup a private network and trying to connect peers. Currently I'm trying it on my laptop and virtual machine(VM) runing on the same laptop (both of them are connected to internet). I ...
0
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1answer
246 views

How ERC20 Token balance are recovered during Ethereum chain rolling-back

My Answer: Ok, the problem is really with Ganache ... If I use geth, everything is alright. ... ... sorry for your time ... ---------------- The Original Question -------------------- My ...
3
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1answer
89 views

How secured are private data stored on blockchain?

I'm quite new in Ethereum world and I'm still little bit confused about this: If I store any data on blockchain, is it readable from anyone? Let's say I have this is Solidity: ... string private ...
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2answers
295 views

signing a transaction on web3js with private key and broadcasting to nodes

I am having an issue with ethereum based project. I made web3 API to communicate to the blockchain. I did this two ways. both call the same function on same address: METHOD 1 (Using Unlocked ...
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1answer
373 views

Deploying Solidity Contract Using Web GUI and web3

Any guide or step by step Tutorial for deploying a solidity smart using a GUI and accessing the meta mask account ? Please Help
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1answer
20 views

is data structures necessary for a blockchain developer?

I want to know if i had to study data structures and algorithms for being a blockchain developer or a smart contract developer
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1answer
230 views

How to connect not local node to private Blockchain?

Is there any way to connect NOT LOCAL node to running private Blockchain? So, there are 3 virtual machines in one local network. They are syncronized private blockchain. They have static-nodes.json ...