All Questions

0
votes
0answers
11 views

Run geth in light mode on Rinkeby and Raspberry

I am trying to run geth --light --cache 64 --rinkeby but it stucks on INFO [02-12|08:58:16] IPC endpoint opened: /home/pi/.ethereum/rinkeby/geth.ipc. I am using geth on a Raspberry. The full output ...
0
votes
1answer
12 views

Recover myetherwallet account with json but without password

I have lost my usb stick which contained password for access to my myetherwallet. Are there any ways to recover that, only thing I have is .json file, can I get from it private key or is there any way ...
0
votes
1answer
22 views

Solidity ,Member“transfer”Not found or not visible after argument dependent lookup in address

pragma solidity ^0.4.11; /** * @title Ownable * @dev The Ownable contract has an owner address, and provides basic authorization control * functions, this simplifies the implementation of "user ...
0
votes
1answer
27 views

Is there any way to get all token transfers of a specific block number?

I am looking for a way to get all erc20 token transfers with specifying block number only. For ETH there is already a way exists here. I have done some search and found this method to find transfers ...
0
votes
2answers
16 views

Parity node is slow in syncing ethereum Ropsten net

I'm using a parity node for the purpose of checking transactions, address balances and generate new addresses via the RPC interface. I noticed lately that the balance of the addresses are not updated ...
0
votes
0answers
15 views

Contract deployed address

Is there a way to save the deployed contract address into a variable. Something related to a constructor that save the deployed address into the variable?
1
vote
1answer
16 views

Warning: Functions in interfaces should be declared external

I have a following interface function: pragma solidity ^0.4.24; interface myInterface { function registerUser(string memory email) public return (bool success); } contract myContract is ...
1
vote
1answer
25 views

What is the difference between these 2 smart contracts?

I noticed some smart contracts have there name,symbol, and supply set up like this example #1 and setup a defined constructor. Notice, they did not fill in the "string public symbol", "string public ...
0
votes
1answer
18 views

truffle migrate does not return anything

I am following the tutorial from Truffle to create a "pet shop" contract. I can follow everything until he tells me to truffle migrate. Here is the contract: pragma solidity ^0.5.0; contract ...
0
votes
0answers
8 views

eth information [on hold]

I have a question. Currently I collect eth information. But I can not find it anywhere. I found btc soon. Bitcoin btc = coin_type ( name = "Bitcoin", symbol = "btc", public_magic = "0488B21E", # ...
0
votes
0answers
12 views

How do i access tokes attached to Poloniex ETH wallet? [on hold]

I have a ETH wallet address that belongs to Poloniex, there is a contract attached to that with my tokens but i can "move" or trade with them, what steps do i take to gain access? is there a platform ...
0
votes
0answers
10 views

Understanding web3.eth.subscribe('newBlockHeaders')

I am running two nodes in a testnet. Node1 = miner and Node2 = peer of Node1 I suscribe to both nodes with web3.eth.subscribe('newBlockHeaders') since I want to obtain when a block with a ...
1
vote
2answers
18 views

What is the difference?

I noticed some smart contracts have the wallet address of the creator in the smart contract to send the tokens to the wallet like example #1: Example #1: constructor() public { symbol = "...
1
vote
0answers
8 views

Is it possible to set miner reward on Geth clique?

I have a private network set up with ethereum & PoA clique consensus. Using in geth client miner.setEtherbase(eth.coinbase) on miner nodes, doesn't seems to work. Inspecting in block explorer ...
2
votes
0answers
13 views

Wastage with shorter block time and how it is handled

Comparing to Bitcoin, Ethereum has much shorter block time. It is stated that Bitcoin has 10 minutes set to make least amount of wastage https://bitcoin.stackexchange.com/questions/1863/why-was-the-...
0
votes
0answers
21 views

Contract deployment not working anymore

So I have this following code that was working a couple of weeks ago and today I decided to run a few tests and it just doesn't do its job anymore. function approve(rid, guest_wallet, ctr_key, dti, ...
2
votes
0answers
20 views

How to get v,r,s parameters from transaction receipt in remix ide?

I am trying to get v,r,s parameters of a transaction so that I can use them to verify the signature. I am not sure but I think previously remix used to give these parameters in transaction receipt. I ...
0
votes
2answers
23 views

sending signed transactions from contract

Is it possible to send private key signed transactions directly from the contract? The thing I want to do is to create a similar function function sendTransactionForUser(_signedData, contractAddress)...
0
votes
0answers
12 views

Geth syncing fast Ropsten too long delays between importing new segments

i have a problem with my Geth Ropsten node. Time between importing new segments of chain is too long. For example logs from my docker container below geth-testnet_1_6d184080c9e1 | INFO [02-11|13:30:...
1
vote
0answers
33 views

Can solidity bytecode has unreachable code

I've compiled contract from https://theethereum.wiki/w/index.php/ERC20_Token_Standard (Sample Fixed Supply Token Contract: contract FixedSupplyToken version:0.5.1+commit.c8a2cb62) I try to make ...
0
votes
1answer
15 views

Real estate ionic application using blockchain and smart contract [closed]

I made a real estate application using ionic. Now I want to know how a real estate property contract will work under smart contract and how. Can someone please guide me with the whole process and the ...
0
votes
0answers
8 views

How to set sealers in extradata genesis block in PoA?

Which is the sintaxis to set up the sealers in extradata field? This is an example: "extraData": "...
1
vote
1answer
16 views

Get a Tx hash from truffle

I have implemented a function call in truffle(web3js): await this.token1.transferFrom(holder1, holder2, transferAmount, {from: holder1}); and now I want to get the tx hash for that specific function....
0
votes
1answer
24 views

Interfaces in solidity

I have one interface like the following: pragma solidity ^0.4.11; interface TokenInterface { function transfer(address recipient, uint amount) external returns(bool); } And the implementation in ...
0
votes
0answers
11 views

Pre Byzantium Transaction Status [duplicate]

How should I find the status of transaction(success/failed) that happened pre Byzantium in the Blockchain?
0
votes
0answers
20 views

Can i convert my HEX private key to RAW form?

Sorry guys if this is a basic question but i am new to this. I have got my private key only in HEX format. converting to raw and then importing or directly making a wallet using HEX private key. Is it ...
0
votes
0answers
17 views

VM error in Truffle

Running the code below returns a vm error: Error: Returned error: VM Exception while processing transaction: revert at Object.ErrorResponse (node_modules/truffle/build/webpack:/~/web3-eth/~/web3-...
0
votes
0answers
5 views

How to read the data from block?

In my smart contract, I am inserting plain text message. I can also update the message. After updating, if I want to see the previous message, is it possible? Can I see all the data in etherscan.io?...
1
vote
2answers
86 views

Variables in interfaces

Im trying to implement my first interface. But when I try to add a new variable, Remix tell me that can´t add variables in interfaces. It have sense to set the fixed variables that the extended ...
1
vote
1answer
23 views

Offchain encryption in Ethereum dapp

Im wrting a dapp which holds / manages sensitive data which might need to be encrypted and decrypted and push again into chain. I know it is not safe to encrypt data in smart contract,which is why Im ...
0
votes
1answer
20 views

ERC20 is an abstract contract or an interface and cannot be deployed

i am trying to deploy a test erc20 token with truffle on ganache-cli My migration file name 2_deploy_contracts.js here is the code for it: var erc20 = artifacts.require('./ERC20.sol'); module....
0
votes
1answer
19 views

Can't create child contract in mainnet?

address[] child; function createChildContract() onlyOwner public{ address newChild = new Child(msg.sender); child.push(newChild); emit ChildCreated(newChild); } contract Child { ...
-1
votes
1answer
26 views

Identity Verification [closed]

I am trying to build a certificate DAPP, where the universities will upload certificates/degrees of students to the blockchain. But How can I verify that the university is genuine and its the ...
-2
votes
2answers
26 views

How to check ETH contract deposit? [on hold]

I want to check ETH contract deposit. ETH contract deposit : (https://etherscan.io/tx/0xc4ae4e2444e91b02633cc771468585c954cc444e300ddceb659776287a4bdd39) { "blockHash": "...
0
votes
1answer
33 views

what is the web3 code for this function

function depositToken(address token,address User,uint amount)public { if (!ERC20(token).transferFrom(msg.sender, address(this), amount)) revert(); _balances[token][User] = _balances[token][User]+...
0
votes
0answers
16 views

Error in syncing of Ropsten testnet on geth node

I am using a geth node to sync with the ropsten testnet . For the last few days I have been encountering the following error frequently Error: invalid gas used (remote: 7987157 local: 7897475) All ...
1
vote
1answer
18 views

Is there any way that smart contract can access xacml policies?

I am trying to implement role based access control model using blockchain. How do i store these policies? Later my smartcontract should be able to allow or deny the rquest of user based on policie. ...
1
vote
0answers
15 views

Why does ecrecover() take signature parameters (v,r,s) instead of the full signature?

Is there any reason ecrecover() takes the (v, r, s) signature parameters instead of the full signature, given that these can be easily computed inside the function itself? I am asking because ...
0
votes
0answers
16 views

Which invocation of 'call' would invoke the fallback function?

Can somebody please guide me which 'if statement' would result in invoking the fallback function? if (msg.sender.call.value(balance)()) { totalBountyAmount -= balance; OR if (msg.sender.call....
0
votes
0answers
18 views

Subscribe to changes in contract balance (Web3j)

Using web3j I would like to subscribe to changes in a contract balance i.e deposits and withdraws. I would like to base this subscription over transactions (and not events) since the contract does ...
1
vote
0answers
17 views

Problem with more than one light node peer connection

I have the following nodes running : FULL NODE and LIGHT SERVER geth --datadir node1 --port 30303 --rpc --rpcport 3003 --rpcaddr 127.0.0.1 --ipcpath node1/geth.ipc --rpcapi="db,eth,net,web3,personal"...
0
votes
0answers
21 views

Whats a good ETH notary service since BTC based OP_RETRUN txns are taboo?

I want to notarize a SHA256 hash of a document I have. Before ETH I would have used a BTC OP_RETURN transaction service. Since BTC is trying to reduce notary spam, what would be a good ETH notary ...
5
votes
0answers
23 views

ELI5 what are erasure codes?

Reading this article, I understand that erasure codes are a potential solution to the data availability issue in sharding. That is, a light node can have higher certainty regarding the contents of a ...
0
votes
0answers
16 views

eth.getCode() always returns “0x”

I want to distinguish between contract addresses and smart contract addresses. But when running web3.eth.getCode() in the geth console with either a contract or a non-contract address, it returns "...
0
votes
1answer
12 views

Light node cannot connect peers

I am running a full node in a testnet and I am trying to connect a light node. I am using the following command: geth --datadir node1 --port 30313 --rpc --rpcport 3013 --rpcaddr 127.0.0.1 --ipcpath ...
0
votes
0answers
11 views

State verification during full sync

How does the state verification work when doing a full sync from scratch? Does the state get generated locally for each block using the transactions downloaded (in the transaction trie) and then ...
2
votes
2answers
24 views

Does a string message increase the gas usage of a `require` statement?

In solc 0.4.22 onward, it is possible to provide a string message containing details about the error that will be passed back to the caller (in require, assert and revert statements). Does the gas ...
0
votes
1answer
15 views

Read storage struct from a modifier

If i read a struct(storage) Human storage human = humans[2]; in my modifier is there a possibility that the function that uses this modifier can use the "human"? Otherwise i have to scope the storage ...
1
vote
0answers
17 views

Parsing Error while compiling pet-shop tutorial

I am just getting started with smart contract programming and was trying to implement the pet-shop example as per this tutorial https://medium.com/tomochain/how-to-build-a-dapp-on-tomochain-...
0
votes
1answer
14 views

Gas displayed on “Remix”

Is Gas displayed on "Remix" at function execution the same as when executed on the main net? I'm using the Javascript VM as the environment.

15 30 50 per page