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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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1answer
22 views

Sound but incorrect change in Merkle-tree

From the whitepaper, The first step in in verifying block validity is: Check if the previous block referenced by the block exists and is valid. With regard to a merkle tree propogating change ...
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0answers
16 views

rinkeby inconsistent state?

I've got a very strang behaviour when running a oraclize call like in the following example: class Test is Oraclize... { uint64[] timestamps; uint64[] numbers; function pushItem(uint64 number)...
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0answers
11 views

Can anyone take me through the deployment of smart contract(written in solidity) and its accessibility using django framework?

I'm a begginer and I've written a smart contract in solidity,started a node that starts mining.I want to access the functions of smart contract from a UI(web app created using django).What do we need ...
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1answer
17 views

What are on chain smart contracts?

My answer would be: On-chain smart contracts -- A set of rules as a transaction committed to the blockchain and then called by subsequent transactions. With on-chain smart contracts, the code that ...
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1answer
29 views

Apart from array and mapping Is there anyway to store large number of user information in Ethereum blockcain?

I have a smart contract to store user information in Ethereum blockchain. For every new transaction entry gets added into map or array. This looks too costly in terms of storage. If I use map or array ...
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0answers
21 views

download Ethereum blockchain

the blockchain now has 6,170,500 blocks. To speed up the download I'm using the method at https://mudra.cloud/ethereum/blockchain.html Is this the fastest method? Does anyone know another faster ...
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0answers
21 views

Error using web3.js from OpenZeppelin

Please, i need hepl. I use truffle to test smart contract. I run "truffle develop", then "migrate". The contract has been stored in the network. Then i run the command "test". An error occurred: ...
2
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0answers
11 views

Retrieve CHAIN_ID of the executing chain from a Solidity contract

Is there a way to directly be able to retrieve CHAIN_ID information about the executing chain from a smart contract? I know that for any chain that has EIP-155 implemented, CHAIN_IDs are retrievable ...
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2answers
319 views

Action taken when data of a block gets tampered with

Let's say we have a Blockchain consisting of 10 blocks, indexed from 0(Genesis Block) to 9(The last block). If the data of a block, say block 5, is changed(maliciously), the data stored on the block, ...
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1answer
25 views

Why is the different “highest block” of --network id 3 and --testnet?

I think both of --network id 3 and --testnet mean to the Ropsten network. But, The result of "eth.syncing" differ from each. --testnet result "highestBlock: 3852529" $ geth --testnet console 2>&...
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1answer
18 views

Payable contract with multiple “options”?

I'm trying to create a contract that behaves differently based on the user's selection. I, however, have no idea how to let the user "select" the option. Currently I have a basic fallback function ...
1
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1answer
23 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 ...
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0answers
13 views

“consensus over state” vs. “consensus over events”?

Does someone know what is difference between "consensus over state" and "consensus over events" ? I found just title of a reference i.e. "Ian Grigg, blog post “The Message is the Medium,” 2017." ...
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1answer
22 views

If it's possible to change solidity code once deployed in ethereum blockchain [duplicate]

I deployed solidity code in ethereum blockchain. Now my client ask to add some function in the deployed solidity code and need update that code in same contract address but i do no if it's possible or ...
2
votes
1answer
17 views

What is an uncle block in Ethereum [duplicate]

I read a lot of sites and answers about uncle blocks in Ethereum, but I did not get it. I am coming from Bitcoin, it is completeley new for me. Can anyone explain me uncle blocks using a concrete ...
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0answers
19 views

How can I implement ethereum If I'm making an exchange service like cex.io [on hold]

I was wondering how cex.io manages ethereum service on their website. I know what happens with bitcoin. They have 1 wallet and daemon on their server for each coin. for example bitcoin. Then When I ...
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2answers
24 views

Could Ethereum Merge with another Coin?

Would it be possible for Ethereum to merge with another coin? If so, how would that work? I ask because GoChain is another infrastructure project which is Ethereum compatible and solves its TPS ...
0
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1answer
16 views

Launch more than one node connected to Rinkeby from the same machine (change the port doesnt work)

I would like to know if it is possible to launch more than one node connected to Rinkeby from the same machine through Geth and Mist. In a local testnet, it is possible to do it changing the --port ...
0
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1answer
30 views

Delegated Proof of Stake (DPOS) vs. Proo of Stake? [on hold]

What is the main difference between Delegated Proof of Stake (DPOS) vs. Proof of Stake? Is there any significant advantage for security? (since PoS in general suffers security problems.) And which ...
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0answers
18 views

How do I call withdraw function from a deployed contract?

I am testing a smart contract I wrote on the Ropsten testnet. The contract was deployed from my original account. I have deposited fake Ether into this deployed contract (Insurance). I want to be ...
0
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1answer
10 views

Access Block Document

I have a requirement where we need to save data(pdf) to blockchain so that any third party can access and view it later by the block address. I can't store the hash of the data on blockchain as the ...
0
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1answer
21 views

In ethereum if i submit any data is it stored in encrypted format? [on hold]

Does Blockchain perform encryption/decryption of data?How and where is data stored in ethereum case.
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1answer
30 views

Block time and confirmation time

I have been reading in different papers and comments these two concepts and I would like to know the difference between them(if there is, sometimes it is a bit confusing). I understand that the block ...
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2answers
34 views

Is there any other blockchain project that implements smart contract

Quite new to blockchain so my question maybe somewhat stupid. I have a blockchain project, where smart contract is required but it also has special requirement such as Proof-of-Importance. I have ...
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2answers
26 views

What is the currency of the field “value” in ERC20 transfers?

I'm trying to understand every fields in an erc20 transfers. But I don't find any informations about the currency of the value field : https://etherscan.io/tokentxns Can someone explain me ?
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0answers
13 views

“Invalid JSON RPC response” using web3.getPastEvent

I am using web3js to query a remote geth node (Geth/v1.8.14-unstable-35fcd2f4/linux-amd64/go1.10.3) for a particular event Ping emitted by a smart contract. myinstance = new web3.eth.Contract(myABI, ...
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0answers
18 views

trading a secret message with some person only after money is paid

I want to build a DAPP where person A trades a message with person B for ether. Since the message is secret, person A encrypts the message by using public key of person B and stores the message in ...
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0answers
20 views

Call a method of another contract via truffle console [duplicate]

I've 2 contract: contract A{ function method() public { //some stuff } } contract B{ A[] private a; function addA() public{ a.push(new A()); } function ...
0
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1answer
10 views

How to incentivize a smart contract DApp without issuing a native token?

Premise: I’m still learning here so I apologize if my question is too basic. My understanding is that technically a smart contract could be built using Ethereum blockchain... no need for native ...
3
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3answers
45 views

EVM - How is it connected to the Blockchain? [duplicate]

I have a few problems understanding the software architecture of the Blockchain. For me Blockchain is the database where all transactions, receipts, balances, etc are stored. But how is the connection ...
1
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0answers
14 views

Ethereum 2nd Layer Solutions, Side-Chains, Child-Chains, Root-Chains: [duplicate]

There are many projects implementing a so-called side-chain or a new chain which works as 2nd layer solution. What does this mean technically? How can one connect a 2nd layer chain with a root-chain e....
0
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1answer
55 views

What address deploys a contract in truffle test

I have a contract called AccessControl, in which the owner of the contract is set when it is deployed. I want to test that the method on it setCEO updates correctly, but in order to do this the ...
0
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1answer
33 views

Running a full node of ETH

I need to run a full node of ETH and its bound tokens for an experimental exchange site. How will I do to differentiate ETH from others tokens ? Is there a way to download the ETH blockchain ...
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0answers
20 views

Converting seconds from January 1, 1960 on a smart contract

I need to change the end time of our ICO to December 31, 2018. I remember there is a site that converts seconds from January 1, 1960. Does this sound familiar? TIA, Steven
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0answers
22 views

How to check last block in which storage variable was modified?

I am looking for method to quick chceck in which block variable was modified last. Assuming I have geth database synced in archive mode, that means I have all previous world states tries and accounts ...
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0answers
23 views

Difference between ethereum blockchain and Hyperledger blockchian

I have found the answers for this question, but still not getting proper answers, that's why I am posting it here for going into dive deeper. I just came to know that Hyperledger in permissioned ...
0
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1answer
58 views

web3.eth.blockNumber is undefined

I have a running blockchain on 128.230.208.73 . I have created local-node on my system using following commands: geth --datadir bkc_data --networkid 89992018 --bootnodes enode://...
0
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1answer
18 views

Initial Genesis difficulty on an ethereum clone

I've created an ethereum clone that i hope someday can become a public blockchain. This is working good so far, however i have a question regarding the initial setup for once i set this live. If i ...
4
votes
3answers
484 views

I get error couldn't find module 'ethereumjs-wallet/hdkey'

I was running this code deploy.js const HDWalletProvider = require('truffle-hdwallet-provider'); const Web3 = require('web3'); const { interface, bytecode } = require('./compile'); const provider = ...
2
votes
1answer
67 views

“being full node” vs.“being sync” : Are they the same?

When we try to be sync using Parity or geth, Does it mean that we are trying to be a full node ? And is it correct to say that: being sync = being a full node = keeping the entire blockchain ?
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1answer
32 views

Better open source blockchain explorer for Quorum blockchain

I was looking for open source blockchain explorers for Quorum blockchain other than https://github.com/blk-io/blk-explorer-free, Thanks
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0answers
14 views

What is a pivot block in ethereum?

i was exploring ethereum codebase and noticed it has been mentioned in so many places about pivot block. I couldn't get a definition on what it exactly means. Could someone explain me what considered ...
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1answer
22 views

How transaction manipulation handles in Blockchain?

I'm new to Blockchain and would like to understand few concepts in a detail. After reading about basics of Blockchain, one thing is unclear to me about tx. manipulation. For instance, A has some (i....
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0answers
40 views

Connecting to blockchain on azure using web3.js and websocket

right now, I am trying to write a service using web3 which will 'subscribe' to all 'perndingtransactions' on blockchain to perform further actions. web3 documentation says that 'Httpprovider' cant be ...
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0answers
4 views

Structure deep copy omits mappings

I'm relatively new to Solidity development, and I've decided to make a sort of gradebook software. I'm trying to copy one of my Course structures from one list to another, like so: catalog.push(...
0
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2answers
27 views

Pass parameter to access modifier

how can I pass a parameter to an access modifier both in Solidity and Web3. Let's assume I have the following code: modifier passwordRequired(string _pw){ require(keccak256(_pw) == keccak256("...
1
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1answer
37 views

Blockchain size versus DAG file size

I am a neophyte(noob) in cryptocurrencies so I'm here at stackexchange with this question, what is the difference between blockchain size and dag file size? Because what actually confused me was the ...
0
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1answer
29 views

Calling contract function via web3.eth.sendTransaction doesnt work

Im learning how Blockchains work and created a private Blockchain to test some things. I deployed the following contract: contract Greeter { address creator; string greeting; ...
0
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1answer
20 views

Accessing older blocks from Geth: Returned error: missing trie node 94d34

When my Nodejs script uses web3 to query a geth node running in a private Ethereum network for an older block, I encounter the error UnhandledPromiseRejectionWarning: Error: Returned error: missing ...
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0answers
14 views

Refresh Peers from `static-nodes.json` Without Restarting geth

When running geth on a private Ethereum network, is it possible to edit the list of enodes in static-nodes.json and make geth pickup any new enodes in the new version of static-nodes.json without ...