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.

Filter by
Sorted by
Tagged with
0
votes
0answers
8 views

Blockchain interoperability

i hope that you are doing well! I wanna build an Blockchain interoperability approach based on side chain and i don't know how to start, so if someone can help me please don't hesitate to text me i ...
0
votes
0answers
12 views

Web3- Sending data to Ganache and then loading a new page to retrieve the same data back

JAVASCRIPT const address = '0x2537155193458a51c99d840e3dBc1f60E004aA85'; var contract = new web3.eth.Contract(abi,address); console.log(contract); $('#invoice-btn').click(function(){ contract.methods....
0
votes
0answers
15 views

How to create a multisg account on Geth server?

As you know, multisig wallets are more secure approach in financial cryptocurrency businesses. In my researches, I found out how can I create a multisig wallet in Bitcoin blockchain using this link. ...
0
votes
0answers
15 views

Walletconnect Signing Transaction not creating request in client

The signing of Transaction is not creating confirm or reject request in the mobile client. Sign in using QR code is working We are using quorum as our RPC. Initialising of connector works but signing ...
0
votes
1answer
24 views

Weird exchange rate when buying DAI with Ether

I wrote code to buy DAI using ETH on Uniswap V2 as follows: function buyCryptoOnUniswap(uint256 etherCost , address cryptoToken) public payable returns(uint256){ //address cryptoToken = ...
0
votes
1answer
19 views

Finality in blockchain consensus

Is Absolute/ Immediate Finality a goal in blockchain consensus or does some areas work better under probabilistic finality such as Ethereum's Pow and to be PoS? (I know that some networks using BFT ...
-1
votes
0answers
10 views

Failing in my first blockchain [closed]

I am learning blockchain, but it has been impossible to pass from this error: Fatal:account unlock with HTTP access is forbidden. I am using Ubuntu in a virtual machine. Please help me
1
vote
0answers
14 views

How does chainlink solve the oracle problem? [closed]

I've heard a lot about Chainlink recently -- how Synthetix, Aave and other top Defipulse projects are using them. How exactly does Chainlink solve the oracle problem from a technical perspective?
4
votes
1answer
64 views

Why do I need decentralized oracles?

I've been reading a lot about how smart contracts work, and I'm a little new to the area, but why do we need decentralized oracles? It feels like I can just make an API call from wherever and it's OK?
1
vote
1answer
30 views

Is a Hash Function really useful in a Smart Contract Election?

Noob here. Was reading this: https://karl.tech/learning-solidity-part-2-voting/ From my basic understanding, a hash function: Receives an input (like x) and spits some result (like y) y is ...
1
vote
0answers
11 views

BlockNumber stuck on 0 while a private network node is looking for peers

I'm extremely new to Blockchain and mining, and I've followed this tutorial to create my first private blockchain. I am stuck when it comes to mining and I'm afraid I'm quite lost. Afte I've started ...
0
votes
1answer
33 views

how to connect ethereum local provider https://localhost:8545? [closed]

I am using infura web3 provider in ethereum but I don't want to use third party providers in my project so I want to use localhost:8545? how to use this provider? Is it connect to the ethereum node? ...
1
vote
2answers
19 views

Store encrypted data on-chain VS on cloud

So, I am currently doing research for a project and an interesting question was born. If I have data that I want to store encrypted, why to choose blockchain instead of a cloud provider? Since the ...
1
vote
1answer
37 views

Blockchain Consenus Protocols Comparison [closed]

Good day community, I do not know if this is the best place to ask as this is the Ethereum Stack Exchange, if not, please let me know. Thank you. I am currently busy with a Master's Project and really ...
0
votes
1answer
19 views

Hashes of all previous blocks are known but why the hash of block.number-1 is vulnerable and not the remaining 255 blocks?

I have read at different places that blackhash(block.number-1) is vulnerable (to miner's blockhash(block.number-1) vulnerability) because the hash is available but what about the other previous 255 ...
0
votes
0answers
14 views

want to get address of account from truffle console to one of the function in smart contract and set some values [closed]

i have 3 accounts in private node. i want to get addresses of two accounts from truffle console to set values in 1 of the function in my smart contract. when i copy paste account address in truffle ...
1
vote
1answer
30 views

How can i create my own version of Metamask? (Wallet, provider and a signer)

I have done a lot of research regarding the working of web3 and the new library called ether.js, Also how the seed phase work in the creation of wallet and addresses and the Hierarchical Deterministic ...
0
votes
1answer
15 views

What is the difference between coinbase address and normal address?

i am unable to find the difference between these two addresses. Do coinbase address also change after each transaction?
4
votes
1answer
109 views

What are the odds of getting same address or private-key or 12/24 set of mnemonic to 2 different people

Questions!! What are the chances that 2 people get the same set of those 12 or 24-word mnemonic?? In web3.js, there is a function ' web3.eth.accounts.wallet '... It spits out a set of accounts and ...
1
vote
0answers
49 views

Solidity function calls from javascript work locally but fail on ropsten,kovan etc with Error: Returned values aren't valid, did it run Out of Gas?

I have a smart contract whose function calls works fine when called locally using javascript and ganache. But when I deploy to ropsten and others, the calls to its functions fail with Error: Returned ...
0
votes
1answer
18 views

Proof that a variable is truly random [duplicate]

I have thinking of the wonder that an application could offer if it could prove that some of its data are truly random and so not controlled. Can the ethereum blockchain offer such a service and how ...
1
vote
0answers
20 views

How to speed up ethreum transaction after initiating

Is there any possibility to speed up transaction after creating transaction receipt. My project need to similar functionality we have with metamask is there a way we can accomplish this using any ...
1
vote
0answers
21 views

We need separate hyperledger stack exchange! [closed]

What do you guys say? I think we need a new community so that we don't mix hyperledger and ethereum questions.
1
vote
1answer
26 views

How does NONCE prevent a replay attack in case of knowing NONCE value?

I have a question about a nonce in the Ethereum network. I understand that a nonce helps to prevent a replay attack, but there is one particular part that I don't understand. I have applied my ...
1
vote
1answer
23 views

State only node

Is it possible for the network clients to just keep the latest network state (without keeping track of the past transactions) while not harming the network security? That is, is it really needed to ...
0
votes
1answer
23 views

ParserError: Expected primary expression - address payable - payable()

I'm trying to get myself familiarized with ethereum. So I was going through a repo, and tried to rum the code : function transferFundOnResolve(uint cid) private { // Could also be used: ...
0
votes
0answers
13 views

Any good recommendations on online courses for learning how to build decentralized apps?

There's one called DappUniversity, but wondering if there are any other courses. And where did you learn how to build dapps? Thank you!
1
vote
0answers
14 views

is “newBlockHeaders” in web3 emits a legit block?

I'm using web3.eth.subscribe('newBlockHeaders') to track transaction I sent to the blockchain. My question is that is the block emitted from "newBlockHeaders" legit or in other words, the block has ...
0
votes
0answers
8 views

How can we write the geth cache data on to the disk?

Recently we ran into an issue where all the nodes of our ethereum consortium network are crashed at once, as all are in same data center. In this crash, we lost the cached data of geth and so as a ...
1
vote
2answers
27 views

Which operations can change ethereum address balance?

I am writing a program that would monitor changes in balance of a set of ethereum addresses. I did the same for UTXO based coins, and the logic was pretty simple. All of the changes were directly ...
0
votes
1answer
49 views

Could not find a declaration file for module 'solc''

I have installed solc without any errors or warning, but when i am trying to run node compile.js command in cmd then i am getting following error On checking the code, i found that "const solc = ...
0
votes
1answer
17 views

Any email signIn based blockchain wallet APIs for integrating into web dapps & native dapps (Android, iOS)?

I'm looking for an email SignUp / SignIn based blockchain wallet which provides API for integration into web dapps and native mobile dapps (Android & iOS). During payment routine in dapps, this ...
0
votes
1answer
40 views

Blockhash: Register the block number

I am reading the following article from a website: bad randomness In the context of Blockhash the author says: For instance, a good protocol (formulating a random trial as a “bet”) is the following: ...
0
votes
0answers
16 views

Ethereum Logs since Beginning of Time

I can subscribe to all events in ethereum network (logs, pendingTransaction etc) so I can get only newly generated events (while I am subscribed). For my analysis I need to retrieve all logs from ...
1
vote
1answer
46 views

DApp examples containing complete source code

can someone provide me some high quality ethereum dapp codebase examples? This should comprise of not only the smart contract codebase but also the app codebase , complete with the front end UI (...
2
votes
1answer
28 views

What is meant by on-chain randomness? What is the difference between on-chain and off-chain operations in the context of randomness?

I want to understand on-chain and off-chain operations in the context of randomness. Kindly provide me an example so that its clear to me. I got one post here: What are offchain and onchain ...
1
vote
1answer
22 views

Maximum totalSupply of an ERC-20 token? And is it different for any other ERC specifictiond?

uint256 This storage implies that it should give us a max totalSupply of 2^256 - 1. A HUGE number. Note: I only need to store integers, not fractional values for my application. Is this true? Is ...
2
votes
0answers
25 views

Why does Ethereum use JSON-RPC and not gRPC?

I am fairly new to networking protocols especially JSON-RPC and gRPC as they are not nearly as common in web development as REST. I was reading around and seems like gRPC generally performs better. So ...
0
votes
0answers
39 views

How to send an array of structs from web3js to solidity contract?

I am getting an error when passing (javascript array of objects) from web3js, To solidity function that takes (array of structs) as a parameter. could you help me? below is the code and the error /...
0
votes
1answer
16 views

How would a miner include my tokens merged mining function in blocks they mine?

So I have a merged mining token. How would a miner include my function in the blocks they mine? pragma version: v0.4.26+commit.4563c3fc.js Merged mining code: function mineTokenReward() { ...
0
votes
0answers
26 views

Accessing modifier of another smart contract - Role Based Access Control

I am trying to create a simple role based access control system for the contracts I have created. I have two smart contracts, one named Users that stores all of the users details as well as the type ...
1
vote
1answer
35 views

How can I implement a custom blockchain?

I am doing a research project which requires me to implement a blockchain with pBFT consensus algorithm. The blockchain would be very simple - A client should be able to send 2 values, the validators ...
0
votes
1answer
24 views

Couldn't get any accounts!, Ethereum client is not configured correctly

I'm running testrpc on the default port 7545. I run truffle console and test with: web3.eth.getAccounts().then( function (result) { return result[0] }); This works fine. According to docs the ...
0
votes
1answer
28 views

Verifying ERC20 Contract that uses OpenZeppelin's library contracts

I deployed an ERC-20 Token contract and would like to now verify it on etherscan.io My contract utilizes Open-Zeppelin's library of contracts - which means it's importing one of their contracts into ...
0
votes
1answer
29 views

How Blockchain system maintenance is done without downtime in real world?

I have a question regarding the maintenance of blockchain system. Whenever any new release comes up then how are the changes made in blockchain without downtime in real world? or is downtime there? I ...
0
votes
0answers
23 views

How to schedule a transaction to a Contract? [duplicate]

I have a simple getter-setter contract. I want to schedule transactions for a method of my contract on a particular date and time. Do we have a function to schedule transactions to a contract in ...
0
votes
1answer
17 views

Current State concept in Blockchain

Anybody explains what does this statement means, 'Blockchain is not a snapshot of current state'.
2
votes
1answer
17 views

What is the difference between IPDB and Blockchain Databases?

I wanted to know what are the differences between IPFS, interplanetary file system and a block chain database like IPDB and BigChainDB
1
vote
1answer
19 views

Isn't the blockchain size going to be a huge problem in the future? [duplicate]

At the moment the blockchain is already quite large. And since the main idea behind the blockchain technology is to get away from services that provide the information and rather have the information ...
1
vote
0answers
39 views

Geth server syncs itself very slow on SSD storage

This is the second time I've lunched a Geth server with full mode on a server with the resources below: 4Core CPU 16GB RAM 400GB SSD But server keeps staying arount half of highestBlock and its ...

1
2 3 4 5
36