Questions tagged [blocks]

This tag is for questions dealing with the structure of blocks.

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Block number as part of header rationale

It seems to me that block number is something that can be derived correctly by a node locally (from the parent block relationship). What was the purpose of including it in block header -> making it a ...
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1answer
25 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: ...
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1answer
14 views

Blockhash Minus-256 Problem [duplicate]

What is meant by Blockhash Minus-256 Problem? I am reading an article at: Bad Randomness It talks about Blockhash Minus-256 problem but does not explain much about it. As a result I can’t ...
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1answer
26 views

Is Ethereum block header a list?

Decoding a RLP encoded block using Eth specifications do we get header as list? But as per format i.e., [[blockHeader,transactionList,uncleList],totalDifficulty], blockHeader should have been string. ...
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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 ...
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1answer
576 views

How to retrieve ERC20 from a hacked address monitored by a bot?

Check it out: https://discordapp.com/channels/554623348622098432/633092550407749652/714325610050355260 The address that was hacked: https://etherscan.io/address/...
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1answer
42 views

Is there any library to estimate timestamp of future block?

I am in need of a library that estimates a date or some sort of timestamp when fed with a future block number (on mainnet or any major testnet). For instance, https://etherscan.io/block/countdown/...
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1answer
90 views

Looking for an Ethereum sniffer

I have been looking for a sniffer similar to Bitcoin P2P Network Sniffer (https://github.com/sebicas/bitcoin-sniffer) which could allow me to connect to Ethereum nodes and listen to blocks and ...
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1answer
29 views

Spending funds before the block is mined

Suppose I have an application that receives funds from users and instantly moves them into an associated cold storage account. If one of our nodes detects a transaction broadcast to one of our ...
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72 views

How is etherscan calculating block size (bytes) from gas used?

https://etherscan.io/block/9980912 It says "The block size is actually determined by the block's gas limit". Not sure how to convert gas used to bytes and geth doesn't provide the block size in bytes....
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3answers
358 views

Transaction receiving ether from a contract address

Are transactions sending ether from contract addresses to normal addresses listed in block.transactions or are they not trivial to detect? If not in block.transactions than how to detect?
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1answer
19 views

web3.eth.getBlock isn't triggered

Basically, i want get the callback result of first method to get each index value in pass it to the second method to scan this value, in this case is an ethereum transaction to get the input value. ...
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What’s the transaction ordering inside a block? [duplicate]

The game I found a game where each gambler needs to pay 0.02 ᴇᴛʜ to register a secret before the game before the games switch to status==reveal each day. Then, during the status==reveal period no ...
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1answer
42 views

Getting the last synced block is 0

I am trying to get last synced block but it always 0. So I have run geth --syncmode fast -cache 4096 --rpc Here is a logs INFO [12-19|09:47:50.058] Imported new state entries count=...
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1answer
41 views

How will Proof of Stake affect blockhash generation

When (and if) Ethereum switches to proof of stake, how will the hash of blocks (most likely) be set?
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30 views

When is a “shard block” cross-linked into a “finalized beacon block”?

In Ethereum 2.0, a shard block for being finalized needs to be linked into a finalized beacon block. Under which conditions a "shard block" cross-linked into a "finalized beacon block"? Having 2/3 of ...
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1answer
87 views

How do Miner choose transactions for a block?

i am wondering how a Miner chooses the transactions, he want to mine inside a block. For example, a Miner has got the Transactions T1 and T2 at the moment he starts a new mining work. This Miner is ...
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1answer
31 views

Are there block rewards for ETH2 validators during Phase0

ETH2 is rolling out in multiple phases. The first phase (typically called phase 0) is the minimal beacon chain. Does this chain already include block rewards? If not, what's the incentive to stake ETH ...
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1answer
63 views

How transactions are selected by the miners?

The deployment of transaction executions is bounded by the block gas limit that changes dynamically. If a block fits only one transaction, then the gas limit per transaction is, in theory, the same as ...
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1answer
40 views

Will block numbers be sequential on a sharded blockchain

When Ethereum shards (assuming it does) will the block numbers across the multiple shards be unique? I doubt it (I don't think the shards can have sequential block numbers and be independent of the ...
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1answer
26 views

What's the difference between a Slot and a Block?

I'm running a private beacon chain with the Lighthouse client with some local validators: Mar 23 10:35:08.281 INFO Block from local validator block_slot: 13009, block_root: 0x2bab…25a6, ...
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1answer
32 views

What is the block number of the first block mined in a private blockchain network deployed on say Quorum?

I am working on POCs on Azure Blockchain Service. While working on quickstarts, I observed that while deploying my 'Hello Blockchain!' smart contract, the block number of the block mined was 34136. ...
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1answer
41 views

What if a malicious validator denies to sign a new block in a shard committee in Ethereum 2.0?

In Ethereum 2.0 (Sharding Blockchain), a new block requires to be signed by all the validators as members of a committee, where blockchain has been sharded in smaller parts for supporting parallel ...
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2answers
404 views

Modify number of confirmations

By default there are 24 confirmations but I am running a testnet with just 3 miners and I would like to change this number bucause it makes not sense to have 24. I have been checking ...
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2answers
71 views

Who are the miners?

In blockchain there are some miners who calculate hash and get reward but my question is who are the miners or how can I be a miner (assume). If there are then I can be connected to a miner? I am ...
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0answers
36 views

Blocks can't contain more than 81 transactions

I'm building a private blockchain with Parity clients. For performance testing, I'm submitting many identical transactions. One of the nodes has a GPU miner attached. There are 2 issues I cannot ...
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1answer
220 views

How to read previous blocks data?

I'm new to block chain technology. I'm trying to store and read blocks using testRPC along web3.js. I'm able to get the latest block data but not able to fetch previous blocks data. Please some one ...
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1answer
36 views

4.3.1. Transaction Receipt-Yellow Paper

I am trying to understand the following function which appears in section 4.3.1 of the Ethereum Yellow Paper: The function description state it "prepares" a transaction receipt, does it mean that the ...
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1answer
18 views

What is the max number of Blocks which can be created in Quorum

I have nodes running from past few days, with almost 4100+ transactions successfully completed. When i try to interact with the contracts again to add/modify details it shows error Error when ...
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1answer
227 views

How to get erc20 contract deploy time / block number

I am building a framework for ERC20 tokens. Aim is to scan all events (Transfer and Approve) generated by ERC20 contract, for which I am using web3.js getPastEvents. I have set the toBlock to web3....
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2answers
60 views

How does Ethereum prevents a node from mining a block with tempered transaction?

My question is rather simple, and I found this question in the Bitcoin StackExchange that somehow relates to mine, although, for the Bitcoin Blockchain, which I'm not sure if Ethereum solves the ...
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2answers
38 views

Can anybody here help me in understanding how transactions and block is getting verified [closed]

Please help me in understanding how transactions are getting verified and also how blocks are getting verified before appending it to the canonical chain.
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1answer
21 views

Integrity of old blocks in the blockchain

I am learning Ethereum using Geth, and I am testing PoA-Clique networks. Now I have a conceptual doubt about old blocks integrity. Suppose I have a private blockchain network of only one miner node ...
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1answer
40 views

Multiple GasLimits on my Private Ethereum network?

I am wondering if it is available to make multiple gas limit block in one of my private networks. The multiple gas limits blocks in a private network means that size 10, 100, 1000 and so on, those are ...
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1answer
556 views

How to get the value of the transaction?

I am using web3.py but I need help to know the value of the transaction sent. I know that the information is stored in the input but how do I parse the string. I know nothing about ABI. Here is the ...
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1answer
1k views

My friend sent me a screenshot of a transaction hash, but when I search for it I find divergent data. What happened?

This is the transaction hash: 0x90e923ee01d9dfeb95ee176819eeec67d247fc6cb009c8cdc4d8ae1939e5ecc6 And this is the screenshot my friend sent me: If you check the hash in Etherscan, some informations ...
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2answers
4k views

Relationship between Transaction Trie and Receipts Trie

Reading through the Yellow paper, I can see that each block header includes the Keccak 256 hash of the root of the trie for transactions and transaction receipts. I am struggling to understand how and ...
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1answer
23 views

Make sure I don't jump any blocks

I'm making a simple program to track transactions in and out of an address, I have a function that gets the latest block and then I run it consecutively. When I run the function sometimes the block ...
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0answers
19 views

What happens if in the genesis file, I put something different than 0(0x0) for the “number” property?

From what I have understood, the number property from the genesis file represents the block number (to match block structure). So, logically, it should be 0x0 because the genesis file is the first ...
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1answer
56 views

Private Clique network, where can I get block sealer and block reward?

Private blockchain PoA validation algorithm Using geth attach MY-GETH-CLIENT, I want to check the sealer of a block as well as its reward. Using eth.getBlock(BLOCK-NUMBER), the miner field is ...
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1answer
30 views

Writing string to separate block in Ethereum

Is it possible to take input of a string from client side and using smart contract write that string data to a new block inside the Ethereum blockchain mainet or any testnet? Basically take in ...
2
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1answer
61 views

How to calculate average time it takes for a transaction to be added to Ethereum blockchain?

In the following article (LINK) we read: "despite the fact that at the time of this writing a new block is produced approximately every 10–20 seconds the average time it actually takes for a ...
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1answer
40 views

Web3: can last block be replaced?

I'm using web3py's getBlock function to get the latest block. I am right now caching the latest 50 blocks so that I reduce the amount of workload in my geth node, and to improve overall speed in my ...
2
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1answer
41 views

Can the block number be set back in ganache?

I know about tools like ganache-time-traveler that let you advance the block number. But is it possible to go back to a lower value?
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1answer
19 views

In ethereum network how data structured and is every data stored, is public?

Let's say, 3 companies are using ethereum network. Company A Company B Company C Company A put some data, block01 and block02. So ethereum network looks like, Genesis Block -> block01 -> block02 ...
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4answers
8k views

How can I get the data of the latest 10 blocks via web3.js?

How can I get latest 10 block data by using web3.js like most block explorer does?
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2answers
28 views

Does a transaction that consumes the block gas limit take an entire block by itself?

Does a transaction that requires the entire block gas limit to be executed (currently ~8M) take the entire block by itself? And if that's true, will that transaction take longer to get confirmed than ...
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3answers
15k views

Is it possible to cancel a transaction?

Is it possible to cancel a transaction broadcast to the blockchain? Suppose I broadcast a transaction and want to cancel it before it has been mined. Is this possible? This could be useful on ...
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1answer
22 views

Can I rely on certain oracle to know the precise and reliable timestamp?

I am learning the security impact of smart contract on system properties like block.timestamp and block.number. I understood that block.timestamp can be controlled by the miner to certain degree and ...
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3answers
360 views

Increase block number on Ganache

How can we increase block.number on Ganache for testing purpose ? If not possible do you know an alternative like passing X fake transactions to artificially increase block.number. Or if we have to ...

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