Questions tagged [block-header]

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Fetching block template from node

The most famous opensource pool uses eth_getBlockByNumber method with parameter "pending" to get block template and generate jobs from it. But now, in parity, I found that this parameter is deprecated ...
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25 views

What is the m_seal fields in the block header used for?

Can someone please explain what these extra fields in the block header are and what are they for? Edit: Oh, I just understood myself -- mixHash and nonse are stored here. But why is this data ...
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1answer
40 views

Verify a block exists

I want to verify that a block exists in a trust-less manner - i.e. with on chain validation. This rules out the option of using an oracle. I'm aware of this function: blockhash(uint blockNumber) ...
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1answer
192 views

Block header hash calculation [duplicate]

What inputs go into the RLP and Keccak function to calculate the block header hash? I looked up the header struct. Which of those values are fed into the RLP, Keccak? Were nonce and mixed hash left ...
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1answer
85 views

block hash from block-header rlp [duplicate]

Given the RLP of a block header, how do i get the block hash? https://github.com/ethereum/go-ethereum/blob/master/core/types/block.go#L99 The above link says: Hash returns the block hash of the ...
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1answer
218 views

block-header hash verification

As part of a validation service I am working on, I need to be able to verify that the blockHeader hash was created correctly. Based on my understanding following are the steps to regenerate the header ...
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2answers
77 views

can only change header's extra data to mine a new block? [closed]

Fix 'nonce' and 'mixDigest', only change 'extra' to mine a new block.
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1answer
23 views

Strange Ropsten Bug - transactionsRoot and recieptsRoot has same value

I'm testing some stuff on Ropsten network and I've found strange block: 4138624 When I run (using web3 injected in Metamask): web3.eth.getBlock(4138624,function(err,res){ console.log(res); }) I'm ...
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1answer
34 views

Why is LH repeated in equation 35 of the yellow paper?

Excerpt from page 5 of the yellow paper, version e94ebda: I understand that LX is the preparation function for serialising X, as follows: LB for blocks LH for block headers LU for ommer block ...
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55 views

how to check if a block has a transaction to an address only by using the block header

Question is self explanatory. How can I check if a block has a transaction to or from an address only by using the block header? Question is prompted by this comment - How to explore all ...
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1answer
70 views

Addresses in paths of State Patricia Trie

Every block header has 3 patricia trees. In State Patricia Trie, the paths are the sha3 of the ethereum addresses, and the value for any particular address is encoded with RLP. But, what addresses ...
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1answer
76 views

What would an Etheruem-like blockchain look like if each block were just an IPFS hash?

I see a lot of people tout the enormous benefits of using IPFS as a store of data. Meanwhile, the Ethereum blockchain is over 1TB in size, with quesitonable need to keep the earlier blocks. In ...
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2answers
358 views

Is a block number unique or does it change if the block becomes uncle? Does the transaction hash include a block hash as input?

Is a block number unique or do I need to save block hash to identify a block? Does transaction hash include a block hash as input?
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2answers
339 views

How Geth and Parity resolve timestamps when validating block headers?

Geth and Parity nodes differ in a fundamental way when they validate block headers. Background According to the yellow paper 4.3 timestamp: A scalar value equal to the reasonable output of Unix's ...
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0answers
224 views

Ethereum Node Connection Error

I'm having trouble getting into my Mist wallet as of a few days ago. Error starting protocol stack: missing block number for head header hash.Having trouble with Ethereum's mist wallet. I have the ...
3
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1answer
710 views

Block header format

Does anyone understand what each element of a block header represents? I have an example block header represented here: [ cd7bd64fba4cc782fe5474d3640882afece5887180591e72f80ce6916cf73526, ...
4
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2answers
485 views

How is the nonce in a the block header arrived at?

My understanding is that the nonce in the header of an Ethereum block is an integer within a certain range (greater than 0). However, when I look at the blocks through an online block explorer, such ...
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0answers
132 views

Rolled back headers dropping the peer right after. geth 1.6.0 [duplicate]

As you can see in this picture I get the same problem over and over again. Headers aren't downloading, they always roll back to header # 1379306. Does any body know what would be the problem here?
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1answer
203 views

Can contracts access the block header extraData field?

The yellow paper (see section 4.4) defines an extraData header field as follows: An arbitrary byte array containing data relevant to this block. This must be 32 bytes or fewer Can contracts ...
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1answer
68 views

How large are header scalar values?

The Yellow paper talks about "scalar values" in section 4.4 to describe block header fields. E.g. difficulty: A scalar value corresponding to the dif- ficulty level of this block. This can be ...
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1answer
1k views

How large are the Ethereum block headers?

I am interested in knowing the block header size to estimate the overhead of running an Ethereum light client.
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2answers
27k views

What is an Event?

What is an Event? Are they only used in Solidity? How are events defined? How are events initiated? Is there a standard term for an event's invocation (do you say an event "happened", "was called",...
1
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1answer
577 views

How are the blocks traversed?

How are the blocks traversed? Is it using a linked list concept to traverse? If I need to see all block details, will it traverse from the genesis block to the requested block or will it traverse ...
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1answer
609 views

Block header structure change under Proof of Stake?

The yellow paper describes the below block header structure: This includes difficulty, beneficiary, mixHash and nonce values. Presumably these will be redundant under Proof-of-Stake. How will the ...
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0answers
414 views

geth throwing header invalid error all the time

lately my ethereum node is repeatedly throwing this error: E0811 16:44:00.646126 core/blockchain.go:1128] uncle[0](30508438) header invalid: nonce for #2004585 [...
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1answer
436 views

What is the beneficiary in block header?

There is the data called "beneficiary" in block header. What is this data?
4
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1answer
437 views

Is block's timestamp current block's or previous block's timestamp?

When I call function giveTime, is the time stamp "now" from the block where my call is mined or from the previous block? contract Time { uint time; function giveTime() { time=now; } ...
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1answer
22k views

What is a block hash?

When we look at this block - what does the first number Hash: 0xfe88c94d860f01a17f961bf4bdfb6e0c6cd10d3fda5cc861e805ca1240c58553 actually mean? How is it calculated? "Nonce" is the value that is ...
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2answers
3k views

Why are there no leading zeroes in ethereum block hash?

The block hash has to be below certain difficulty, right? In bitcoin this means, that there are many leading zeroes in hash value, eg. for bitcoin block #402329 hash is ...
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1answer
642 views

What's the header hash displayed in the miner?

Is the "hash" value reported by geth: eth.getBlock("849245").hash, for example, the same "hash" that is given to the miner in the work package? Sorry if this is a naive query. The reason for the ...
22
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3answers
6k views

Can a contract safely rely on block.timestamp?

How safe is it to use block.timestamp as contract expiration time? If a miner provides an incorrect timestamp in a block header, how much can it be off before it is rejected by other nodes? Is there a ...
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6answers
49k views

Ethereum block architecture

Where can I find a description (preferably a diagram like below) showing the block structure in an Ethereum blockchain? Credits: Wikipedia