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Ethereum Block Header Structure

Uncle Mining, An Ethereum Consensus Protocolflaw

Uncle Mining, An Ethereum Consensus Protocolflaw

Uncle Mining, an Ethereum Consensus ProtocolFlaw A year ago I was hired by Eth Dev Ltd through Coinspect to perform a security audit on the Ethereum design. One of our findings was that the uncle reward strategy in Ethereum was weird, and could lead to miners abusing the uncle rewards to almost triple the money supply. We discovered this problem because I had been working on the same problem for a long time, and posting in cryptocurrency mailing lists and in this blog about a variation of Nakamoto consensus protocol called DECOR+ , that is based on sharing block rewards between competing blocks. At that time I explained the flaw and suggested to limit the number of uncles to prevent an unbounded money supply function. I assumed the Ethereum core team would pick the DECOR+ protocol sooner or later, but Ethereum has now gone through several programmed hard-forks, and the problem still remains. Last week, and the night before a presentation of the RSK (a.k. Rootstock) smart-contract platform, I decided to explore the problem a little more, and I found to my surprise that the uncle mining strategy theoretically works in Ethereum at very low thresholds, and therefore the current Ethereum consensus protocol is certainly not incentive compatible. Uncle mining strategy consist of forcing you own blocks into uncles (blocks not in the best chain) in order to earn uncle rewards while preventing your blocks from contributing to the block difficulty adjustments. Uncle mining is a greedy strategy (or even it can be considered dishonest), as the greedy miners get monetary compensations while providing less of the expected service to the network: uncle mining does contribute to securing the network due to GHOST weighting, but does not contribute to increasing the network transaction p Continue reading >>

Peacerelay: Connecting The Many Ethereum Blockchains

Peacerelay: Connecting The Many Ethereum Blockchains

PeaceRelay: Connecting the many Ethereum Blockchains Last week I attended the IC3-Ethereum bootcamp at Cornell University, Ithaca. The bootcamp was designed as an one-week long hackathon in which attendants, including both academic and industry people, were split into groups to work on different projects. I proposed and lead PeaceRelay, one of the ten selected projects. Project leaders pitched their projects to the attendants on the first day, after that people could register and select which project they want to work on for the rest of the bootcamp. I was fortunate to work with Nate Rush and Nicholas Lin on PeaceRelay during the bootcamp. PeaceRelay is inspired by BTCRelay , a Bitcoin light-client running within a smart contract on Ethereum. BTCRelay allows Ethereum smart contracts to verify Bitcoin transactions, thus enabling Ethereum accounts to receive payment from Bitcoin. PeaceRelay is built with a similar goal but for different chain: allowing communication/ interaction between two different Ethereum blockchains, i.e Ethereum and Ethereum Classic. Via PeaceRelays services, Ethereum contracts can read and verify transactions, account states on Ethereum Classic and vice versa. PeaceRelay is much more interesting than BTCRelay at the moment, since it enables two-way relay between Ethereum and Ethereum Classic, thus enabling what is also called two way peg in sidechain. Basically, PeaceRelay allows one to move ETC to Ethereum and move it back to Ethereum Classic network by deploying PeaceRelay on both Ethereum and Ethereum Classic networks. How PeaceRelay works is quite simple. Lets first discuss how BTCRelay or any general chain relay works. There is an Ethereum contract that stores all Bitcoin block headers relayed/ submitted by users, or relayers. In case you are Continue reading >>

Ethereum Wallet Syncing Problems

Ethereum Wallet Syncing Problems

One of the most common problems with the Ethereum Wallet application is keeping the blockchain in sync with the Ethereum network. This page describes some of the common issues users may encounter while trying to sync the blockchain and potential methods to work around the problems. Note that Ethereum Wallet will not display your account balance correctly when it is not synced fully or correctly. Check that your the clock on your computer is close to real time. Change your system settings so that your system clock is synced to an NTP (Network Time Protocol) server. Slow Syncing Between Blocks 2,283,397 And 2,717,576 You may be encountering some problems syncing Ethereum Wallet (or Mist) to the Mainnet blockchain. A common problem when syncing Ethereum Wallet's blockchain data is that the syncing slows down between blocks 2,283,397 and 2,620,384 due to the attack on the Ethereum network (reference Why is my node synchronization stuck/extremely slow at block 2,306,843? ). The syncing also slows down between blocks 2,675,055 and 2,717,576 due to the state clearing process to remove the 20 million empty accounts created by the network attack. If you have a problem with slow syncing, the easiest way to recover from this slowdown is to remove your blockchain data and restart Ethereum Wallet. Ethereum Wallet will then perform a fast sync which skips over these attack blocks. WARNING: Make sure you back up your keystore directory so you don't accidentally delete your account information. Depending on your operating system, you will find the chaindata subdirectory in: Alternatively, you can run geth removedb to remove the blockchain data. Start Ethereum Wallet. It should now start fast syncing the blockchain data. Alternatively, run geth --syncmode "fast" --cache 1024 console an Continue reading >>

A Gentle Introduction To Ethereum

A Gentle Introduction To Ethereum

Ethereum builds on blockchain and cryptocurrency concepts, so if you are not familiar with these, its worth reading a gentle introduction to bitcoin and a gentle introduction to blockchain technology first. This article assumes the reader has a basic familiarity with how Bitcoin works. Ethereum is software running on a network of computers that ensures that data and small computer programs called smart contracts are replicated and processed on all the computers on the network, without a central coordinator. The vision is to create an unstoppable censorship-resistant self-sustaining decentralised world computer. The officialwebsite is Itextends the blockchain concepts from Bitcoin which validates, stores, and replicates transaction data on many computers around the world (hence the term distributed ledger). Ethereum takes this one step further, and also runs computer code equivalently on many computers around the world. What Bitcoin does for distributed data storage, Ethereum does for distributed data storage plus computations. The small computer programsbeing run are called smart contracts, and the contractsare run by participants on their machines using asort ofoperating system called a Ethereum Virtual Machine. To run Ethereum, you can download (or write yourself if you have the patience) some software called an Ethereum client. Just like BitTorrent or Bitcoin, the Ethereum client will connect over the internet to other peoples computers running similar client softwareand start downloading the Ethereum blockchain from them to catch up. It will also independently validate that each block conforms to the Ethereum rules. What does the Ethereum client software do? You can use itto: Create new transactions and smart contracts Your computer becomes a node on the network, r Continue reading >>

Merkling In Ethereum

Merkling In Ethereum

Merkle trees are a fundamental part of what makes blockchains tick. Although it is definitely theoretically possible to make a blockchain without Merkle trees, simply by creating giant block headers that directly contain every transaction, doing so poses large scalability challenges that arguably puts the ability to trustlessly use blockchains out of the reach of all but the most powerful computers in the long term. Thanks to Merkle trees, it is possible to build Ethereum nodes that run on all computers and laptops large and small, smart phones, and even internet of things devices such as those that will be produced by Slock.it . So how exactly do these Merkle trees work, and what value do they provide, both now and in the future? First, the basics. A Merkle tree, in the most general sense, is a way of hashing a large number of chunks of data together which relies on splitting the chunks into buckets, where each bucket contains only a few chunks, then taking the hash of each bucket and repeating the same process, continuing to do so until the total number of hashes remaining becomes only one: the root hash. The most common and simple form of Merkle tree is the binary Mekle tree, where a bucket always consists of two adjacent chunks or hashes; it can be depicted as follows: So what is the benefit of this strange kind of hashing algorithm? Why not just concatenate all the chunks together into a single big chunk and use a regular hashing algorithm on that? The answer is that it allows for a neat mechanism known as Merkle proofs: A Merkle proof consists of a chunk, the root hash of the tree, and the branch consisting of all of the hashes going up along the path from the chunk to the root. Someone reading the proof can verify that the hashing, at least for that branch, is c Continue reading >>

Understanding The Ethereum Trie

Understanding The Ethereum Trie

The other day I finally got around to reading the entire ethereum yellow paper and to figuring out how the modified Merkle-patricia-tree (trie) works. So lets go through a brief but hopefully complete explanation of the trie, using examples. A block in the ethereum blockchain consists of a header, a list of transactions, and a list of uncle blocks. Included in the header is a transaction root hash, which is used to validate the list of transactions. While transactions are sent over the wire from peer to peer as a simple list, they must be assembled into a special data structure called a trie to compute the root hash. Note that this data structure is not needed except to verify blocks (and hence of course to mine them), and can technically be discarded once a block has been verified. However, it is implied that the transaction lists are stored locally in a trie, and serialized to lists to send to clients requesting the blockchain. Of course, that client will then reconstruct the transaction list trie for each block to verify the root hash. Note that RLP (recursive length prefix encoding) , ethereums home-rolled encoding system, is used to encode all entries in the trie. A trie is also known as a radix tree , and the ethereum implementation introduces a couple modifications to boost efficiency. In a normal radix tree, a key is the actual path taken through the tree to get to the corresponding value. That is, beginning from the root node of the tree, each character in the key tells you which child node to follow to get to the corresponding value, where the values are stored in the leaf nodes that terminate every path through the tree. Supposing the keys come from an alphabet containing N characters, each node in the tree can have up to N children, and the maximum depth of Continue reading >>

From Bitcoin To Ethereum

From Bitcoin To Ethereum

In response to: Cryptocurrencies and Blockchains (Vol. 2, No. 4). Jean-Paul Delahaye explains clearly in his article how the bitcoin protocol works, as well as the enthusiasm and fear it elicits. The major innovation behind bitcoin is the creation of an ecosystem that allows for a decentralized consensus. Users no longer need a reliable central authority to interact with each other. While it is difficult to predict how blockchain technology will become important in our everyday activities over the next few yearsincreasing our happiness, or notthe enthusiasm it elicits is growing. It could have many applications, of which cryptocurrencies are only an initial example. Among the platforms arousing great interest is Ethereum, which allows users to manage and interact with smart-contracts. Ethereum promises applications that work exactly as they were programmed and cannot be interrupted, censored, or modified in any way. It has been spoken of as one of the building blocks of web 3.0! Understanding precisely how all this works in practice is a fascinating subject. How can a user, interacting with the network via only his smartphone, quickly verify that a transaction has been saved on the blockchain? One approach uses the concept of a Merkle tree. This is an important data structure used in computing and cryptography, and I would like to follow up Delahayes article by explaining this point. Another legitimate question that one might ask with reference to the mechanism of transaction validation is: why do bitcoins have real economic value? There is more to bitcoin than simply a currency of exchange. To illustrate this, I will examine in some detail a transaction inscribed in the bitcoin blockchain. This has nothing to do with any financial transaction, on the contrary, it is c Continue reading >>

Block Structure In Cryptocurrencies

Block Structure In Cryptocurrencies

In this article I'm going to provide a brief review of block structure in cryptocurrencies. A variety of cryptocurrencies, starting with Bitcoin are based on blockchain structure. In blockchain multiple transactions modifying cryptocurrency state are grouped into blocks generated according consensus protocol. Blocks are ordered by linking to previous block thus the term blockchain. As blocks are chained, the work to change the block would include redoing all the blocks after it. So block should contain at least transactional data modifying current state, consensus data approving the right to generate a block and a link to previous block. Block structures of different cryptocurrencies are represented below. To fight with the blockchain boat problem, and also in order to provide support for light clients, most of blockchains distinguish block header from the block payload to be able to prune old transactions from the blockchain keeping it secure. The header should be enough to verify consensus data and choose the chain with the best score (cumulative difficulty in Bitcoin jargon) determined by corresponding consensus algorithm. Besides of consensus data and a link to previous block header should contain some digest of transactions to make transactional data immutable. Root hash of authenticated data structure build on top of transactions is usually used for this purposes allowing to prove existence (or non-existence) of a specified transaction in a block. Once block structure may change during cryptocurrency development, it's usually good idea to have block version in header. Blocks of proof-of-work currencies are immutable by design, because it's required to solve computational puzzle one more time to change any data in a block, but proof-of-stake currencies ( Nxt and B Continue reading >>

Go-ethereum/block.go At Master Ethereum/go-ethereum Github

Go-ethereum/block.go At Master Ethereum/go-ethereum Github

// The go-ethereum library is free software: you can redistribute it and/or modify // it under the terms of the GNU Lesser General Public License as published by // the Free Software Foundation, either version 3 of the License, or // The go-ethereum library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU Lesser General Public License for more details. // You should have received a copy of the GNU Lesser General Public License // along with the go-ethereum library. If not, see Continue reading >>

Blockchain - Ethereum Block Architecture - Ethereum Stack Exchange

Blockchain - Ethereum Block Architecture - Ethereum Stack Exchange

Where can I find a description (preferably a diagram like below) showing the block structure in an Ethereum blockchain? Lets first start with my adaptation adaptation of this figure illustrating the Bitcoin block structure: Enter Ethereum and things get a wee bit more complex. After reading through this and this , and as per @ eth 's recommendation this , my best interpretation is the figure below: The header field definitions are available in section 4.3 of the yellow paper . Uncles is a hash (of a list of uncles), Yellow Paper has: "The Keccak 256-bit hash of the ommers list portion of this block". Codehash is just a hash since contracts are immutable. The pointers point to "hash of whole block header" (the Keccak-256 hash of all the bytes in the block header). To have a full diagram, should really consult the Yellow Paper... eth Jan 29 '16 at 22:53 Updated response after consulting the YP. Starting to get clearer now. Thanks! zanzu Feb 1 '16 at 12:34 Why are the transactions from block N linked to those of block N+1? Sebi Jun 10 '16 at 8:31 These links correspond to contract state that has not changed in between blocks. Referencing the state from the previous blocks instead of replicating is more efficient from a block size perspective. zanzu Jun 10 '16 at 9:49 Continue reading >>

Blockchain: What Is In A Block?

Blockchain: What Is In A Block?

In my previous article, I tried to described the concept of a blockchain with code. This time, I'll try to describe the structure of a single block. I will use the Bitcoin blockchain to explain blocks, but keep in mind that the concepts will remain more or less the same. It could be useful to read my last article to understand a few things first. A block is a container data structure. In the Bitcoin world, a block contains more than 500 transactions on average. The average size of a block seems to be 1MB ( source ). In Bitcoin Cash ( a hard fork from the Bitcoin blockchain ), the size of a block can go up to 8MB. This enables more transactions to be processed per second. Anyway, a block is composed of a header and a long list of transactions. Let's start with the header. The header contains metadata about a block. There are three different sets of metadata: The previous block hash. Remember that in a blockchain, every block is inherits from the previous block because we use the previous block's hash to create the new block's hash. For every block N, we feed it the hash of the block N-1. Mining competition. For a block to be part of the blockchain, it needs to be given a valid hash. This contains the timestamp, the nonce and the difficulty. Mining is another crucial part of the blockchain technology, but it is outside the scope of this article. The third part is a merkle tree root. This is a data structure to summarize the transactions in the block. And we will leave it at that for now. More on this later. To identify a block, you have a cryptographic hash, a digital signature if you will. This is created by hashing the block header twice with the SHA256 algorithm. For example, this is a block . I will refer to this block as an example for this article. The block header Continue reading >>

White Paper Ethereum/wiki Wiki Github

White Paper Ethereum/wiki Wiki Github

Introduction to Bitcoin and Existing Concepts The concept of decentralized digital currency, as well as alternative applications like property registries, has been around for decades. The anonymous e-cash protocols of the 1980s and the 1990s were mostly reliant on a cryptographic primitive known as Chaumian Blinding. [8] Chaumian Blinding provided these new currencies with high degrees of privacy, but their underlying protocols largely failed to gain traction because of their reliance on a centralized intermediary. In 1998, Wei Dai's b-money [9] became the first proposal to introduce the idea of creating money through solving computational puzzles as well as decentralized consensus, but the proposal was scant on details as to how decentralized consensus could actually be implemented. In 2005, Hal Finney introduced a concept of reusable proofs of work, [10] a system which uses ideas from b-money together with Adam Back's computationally difficult Hashcash [11] puzzles to create a concept for a cryptocurrency, but once again fell short of the ideal by relying on trusted computing as a backend. In 2009, a decentralized currency was for the first time implemented in practice by Satoshi Nakamoto, [1c] [1d] combining established primitives for managing ownership through public key cryptography with a consensus algorithm for keeping track of who owns coins, known as "proof of work." The mechanism behind proof of work was a breakthrough because it simultaneously solved two problems. First, it provided a simple and moderately effective consensus algorithm, allowing nodes in the network to collectively agree on a set of updates to the state of the Bitcoin ledger. Second, it provided a mechanism for allowing free entry into the consensus process, solving the political problem of Continue reading >>

How Does Ethereum Work, Anyway?

How Does Ethereum Work, Anyway?

Odds are youve heard about the Ethereum blockchain, whether or not you know what it is. Its been in the news a lot lately, including the cover of some major magazines, but reading those articles can be like gibberish if you dont have a foundation for what exactly Ethereum is. So what is it? In essence, a public database that keeps a permanent record of digital transactions. Importantly, this database doesnt require any central authority to maintain and secure it. Instead it operates as a trustless transactional system a framework in which individuals can make peer-to-peer transactions without needing to trust a third party OR one another. Still confused? Thats where this post comes in. My aim is to explain how Ethereum functions at a technical level, without complex math or scary-looking formulas. Even if youre not a programmer, I hope youll walk away with at least better grasp of the tech. If some parts are too technical and difficult to grok, thats totally fine! Theres really no need to understand every little detail. I recommend just focusing on understanding things at a broad level. Many of the topics covered in this post are a breakdown of the concepts discussed in the yellow paper. Ive added my own explanations and diagrams to make understanding Ethereum easier. Those brave enough to take on the technical challenge can also read the Ethereum yellow paper. A blockchain is a cryptographically secure transactional singleton machine with shared-state.[1]Thats a mouthful, isnt it? Lets break it down. * Cryptographically securemeans that the creation of digital currency is secured by complex mathematical algorithms that are obscenely hard to break. Think of a firewall of sorts. They make it nearly impossible to cheat the system (e.g. create fake transactions, erase tra Continue reading >>

Blockchain Developer Api For Ethereum | Blockcypher

Blockchain Developer Api For Ethereum | Blockcypher

# ^# / \ _ _# / ^ \ |_) | _ _ | / ._ |_ _ ._#< > |_) | (_) (_ |< \_ \/ |_) | | (/_ |# \ v / / |# \ /# v Welcome to BlockCyphers Ethereum API documentation! If youre familiar with our Bitcoin endpoints, youll feel right at home with our Ethereum API. However, there are a few differences, and they stem in part from the fundamental differences between Bitcoin and Ethereum. In the most abstract sense, Bitcoin and Ethereum are cousins; they both have blocks of transactions linked together into a chain, they both use Proof of Work to reach consensus (for now, as Ethereum plans to move to Proof of Stake in a future release), they are both about decentralizing trust. But thats where the similarities end. Here are just some of Ethereums differences: There are no UTXOs, only accounts (of two varieties) Block time is significantly shorter; 15 second target instead of 10 minutes Miners get rewards for including references to orphan blocks (so called uncle blocks) Ethereums scripting language is far more expressive than Bitcoins; typically advanced transactions/contracts are constructed using a higher level language then converted into EVM bytecode Ethereum has no strict cap on monetary supply (ether supply) Transactions cost gas to run (denominated in ether) depending on how computationally expensive they are to run. Blocks also have total gas limits to prevent runaway computation/keep the network decentralized. In a nutshell, Bitcoin is about decentralized, trust-minimizing, sound money. Ethereum is about decentralized, trust-minimizing, sound computation. Much more detail about these differences can be read at the Ethereum Wiki here. You can find more information at the projects webpage as well. man curl | grep -A 3 "DESCRIPTION"DESCRIPTIONcurl is a tool to transfer data from or Continue reading >>

Blockchain Tests Ethereum Homestead 0.1 Documentation

Blockchain Tests Ethereum Homestead 0.1 Documentation

The 160-bit address to which all fees collected from the successful mining of this block betransferred, as returned by the COINBASE instruction. A scalar value corresponding to the difficulty level of this block. This can be alculatedfrom the previous blocks difficulty level and the timestamp, as returned by the DIFFICULTY instruction. A scalar value equal to the current limit of gas expenditure per block, as returned by the GASLIMIT instruction. A scalar value equal to the number of ancestor blocks. The genesis block has a number of zero. A scalar value equal to the reasonable output of Unixs time() at this blocks inception, as returned by the TIMESTAMP instruction. The Keccak 256-bit hash of the parent blocks header, in its entirety The Bloom filter composed from indexable information (logger address and log topics)contained in each log entry from the receipt of each transaction in the transactions list. An arbitrary byte array containing data relevant to this block. This must be 1024 bytes or fewer. A scalar value equal to the total gas used in transactions in this block. A 256-bit hash which proves that a sufficient amount of computation has been carried out on this block. The Keccak 256-bit hash of the root node of the trie structure populated with the receipts of each transaction in the transactions list portion of the block. The Keccak 256-bit hash of the root node of the state trie, after all transactions are executed and finalisations applied. The Keccak 256-bit hash of the root node of the trie structure populated with each transaction in the transactions list portion of the block. The Keccak 256-bit hash of the uncles list portion of this block pre section: as described in State Tests. postState section: as described in State Tests (section - post). blocks s Continue reading >>

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