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Ethereum State Trie

Growing A Merkle Tree

Growing A Merkle Tree

Ethereum is a platform and a programming language that makes it possible for any developer to build and publish next-generation distributed applications. Ether, Ethereum's cryptofuel, powers the applications on the decentralized network. import Data.ByteStringimport Ethereum.Word4type Key = [Word4] -- hexadecimal digitstype Value = ByteStringdefaultValue = ByteString.empty lookup :: Key -> AssocList -> Valuelookup key = fromMaybe defaultValue . Prelude.lookup key update :: Key -> Value -> AssocList -> AssocListupdate key value list = (key, value) : list -- TODO: handle duplicates, default values data Trie = Branch [Trie] Value -- 16-element list | Empty lookup :: Trie -> Key -> Valuelookup Empty _ = defaultValuelookup (Branch _ value) [] = valuelookup (Branch children _) (nibble : rest) = let child = genericIndex children nibble in lookup child rest data Trie = Branch [Trie] Value | Shortcut [Word4] (Either Trie Value) | Emptylookup :: Trie -> Key -> Valuelookup (Shortcut prefix result) key = case (stripPrefix prefix key, result) of (Just [], Right value) -> value (Just suffix, Left child) -> lookup child suffix _ -> defaultValuelookup _ _ = ... Shortcut prefix (Right defaultValue) --> Empty Branch (replicate 16 Empty) value --> Shortcut [] (Right value) [...] a hash tree or Merkle tree is a tree in which every non-leaf node is labelled with the hash of the labels of its children nodes. Hash trees are useful because they allow efficient and secure verification of the contents of large data structures. newtype Hash = Hash ByteStringdata Trie = Branch [Hash] Value | Shortcut [Word4] (Either Value Hash) | Empty lookup :: Hash -> Key -> Valuelookup hash key = ??? lookup :: Hash -> Key -> IO Valuelookup root key = retrieveNode root >>= getVal where getVal Empty = return def Continue reading >>

Ethereum/solidity

Ethereum/solidity

if you see at the right the account that execute the function is supposed to be a voter the owner added however, it seems that ( the addvoters[msg.sender].adr == msg.sender) is false , but the 2 addresses are supposed to be the same ( this is what I want to have actually) Can somebody explain me where the satte of a state variable is stored? is it stored on the blockchain or on the RAM of the node? Can somebody tell me when the contract is compiled to bytecode and is on the blockchain how can somebody verify what the smart contract code is and check where he wants to use the smart contract or not? Is it necessary to include the source code somewhere + compiler information? Does this then deterministically compile everytime to the same bytecode? @gernotpokorny state of state variable is saved into state trie/tree. its not saved in RAM of node , it goes in blockchain datastore. I have Error: gas required exceeds allowance or always failing transaction when creating smart contract on remix. @bit-warrior what is meant with blockchain datastore? It is part of the blockchain? how to make contract with avoiding gas exceeds? @gernotpokorny smart contract will be saved on blockchain. Like for Geth, all the data related to the blockchain are saved in levelDB in form of different tries, like transaction trie, state tries, transaction receipt trrie. Level db is key-value database developed by Google. @bit-warrior Ok so that means something like variable-states are generated by the txs and stored on the harddrive of the node. Once a new tx comes in the db on the harddrive of the node gets modified. So erc20 tokens are essentially stored in a database on the node? @SkyClean where are you deploying ur contract local EVM or a outside network? @gernotpokorny ecr tokens are contract to Continue reading >>

The Ethereum-blockchain Size Will Not Exceed 1tb Anytime Soon.

The Ethereum-blockchain Size Will Not Exceed 1tb Anytime Soon.

The Ethereum-blockchain size will not exceed 1TB anytime soon. Before diving into this article, please read the two disclosures about my involvement (1,2) and the one on data accuracy (3) at the bottom of the article. At least once a month someone posts a chart on r/ethereum predicting the blockchain size of Ethereum will soon exceed 1 TB. I want to take that chance to clean up with some stories around the Ethereum-blockchain size in this article and try to explain why this chart is technically correct, but not the full picture. Let's have a look at this chart first. It shows the complete data directory size of an Ethereum node (red), Geth in this case, and a Bitcoin node (blue), probably Bitcoin-Core , plotted over time. While the Bitcoin graph is moving slightly upwards in a seemingly linear inclination, the Ethereum graph reminds the reader of an exponential growing slope. On Blocks, Block-History, States, and State-History Users accusing Ethereum of blockchain-bloat are not far off with their assumptions. But actually, not the chain is bloated but the Ethereum state. I want to examine some terminology from the Whitepaper before proceeding. Block. A bundle of transactions which, after proper execution, update the state. Each transaction-bundling block gets a number, has some difficulty, and contains the most recent state. State. The state is made up of all initialized Ethereum accounts. At the time of writing, there are around 12 million known accounts and contracts growing at a rate of roughly 100k new accounts per day . Block-History. A chain of all historical blocks, starting at the genesis block up to the latest best block, also known as the blockchain. State-History. The state of each historical block makes up the state history. I will get into the details on t Continue reading >>

Design Rationale | Ethereum Builder's Guide

Design Rationale | Ethereum Builder's Guide

Although Ethereum borrows many ideas that have already been tried and tested for half a decade in older cryptocurrencies like Bitcoin, there are a number of places in which Ethereum diverges from the most common way of handling certain protocol features, and there are also many situations in which Ethereum has been forced to develop completely new economic approaches because it offers functionality that is not offered by other existing systems. The purpose of this document will be to detail all of the finer potentially nonobvious or in some cases controversial decisions that were made in the process of building the Ethereum protocol, as well as showing the risks involved in both our approach and possible alternatives. The Ethereum protocol design process follows a number of principles: Sandwich complexity model: we believe that the bottom level architecture of Ethereum should be as simple as possible, and the interfaces to Ethereum (including high level programming languages for developers and the user interface for users) should be as easy to understand as possible. Where complexity is inevitable, it should be pushed into the "middle layers" of the protocol, that are not part of the core consensus but are also not seen by end users - high-level-language compilers, argument serialization and deserialization scripts, storage data structure models, the leveldb storage interface and the wire protocol, etc. However, this preference is not absolute. Freedom: users should not be restricted in what they use the Ethereum protocol for, and we should not attempt to preferentially favor or disfavor certain kinds of Ethereum contracts or transactions based on the nature of their purpose. This is similar to the guiding principle behind the concept of "net neutrality". One example o Continue reading >>

Performance Analysis

Performance Analysis

So with the latest benchmarks (available to see at parity.io), it's clear Parity has head and shoulders the fastest and lightest Ethereum block processing engine amongst the available clients. But aside from the big numbers, it's nice to understand a bit deeper about what's going on underneath. This is a quick dive into the differences between Parity and the currently most popular client on the Ethereum network, Geth. I haven't yet done similar stuff for EthereumJ or Eth, though I expect that might be fun, too. Note that throughout I'm talking about block-processing. In particular, each client processed the same ~1,000,000 blocks in the current "Frontier" Ethereum mainnet. Block processing means checking the proof-of-work and all the transaction signatures, executing EVM code, building and updating tries, managing the death row (in the state-pruning clients) and various verifications. I measured block processing through making the clients do a "full" sync (as opposed to Geth's --fast sync which doesn't do block processing, instead just duplicating the state trie from a remote host) from a pre-synced node running locally. It used to be that block-processing speed was the same as sync speed. With the advent of state-trie-duplicating (aka fast-syncing), this is no longer strictly true: nodes can sync without actually needing to process all those transactions that happened prior (ish - they still tend to process the last 1000 or so). Here we measure block-processing speed - though it's not an especially great proxy for understanding how fast a node can sync, it's still useful for understanding a few other aspects about how fast a node will go. Block processing speed governs how fast a miner will be able to confirm an incoming block and get back to mining on the right chain Continue reading >>

Ethon: Ethereum Ontology

Ethon: Ethereum Ontology

The world state, is a mapping between addresses (160-bit identifiers) of all accounts and their states (a data structure serialised as Recursive Length Prefix). The mapping is not stored on the blockchain itself but in a modified Merkle Patricia tree. An individual state is identified by the root hash of the trie. Instances of :WorldState can have the following properties: This property relates an EthOn concept to a definition in Simple English, intended especially for non-technical users. This property relates an EthOn concept with a suggested string representation. It can be used to give the term a name, e.g. in program code. The Keccak 256-bit hash of the root node of the state trie that represents this state. Groups all EthOn account object properties Superclass of all EthOn specific annotation properties. Groups all data properties specific to EthOn. Groups all EthOn message object properties. Groups all EthOn network data properties. Groups all EthOn network object properties. Groups all EthOn state object properties. Relates a message to the global state of the system after all the message has been executed. Relates an account to the Merkle Patricia tree that encodes its storage contents at a certain account state. This property is Functional because an account state can have only one instance of account storage and inverse functional because an account storage can have only one associated account state. Relates a state to a transition (i.e. a message) that creates a new state. This is a general relation to express part of relationships. The classic study of parts and wholes, mereology, has three axioms: 1. the part-of relation is Transitive - "parts of parts are parts of the whole" - If A is part of B and B is part of C, then A is part of C Reflexive - "Everyth 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 secure means 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 tr Continue reading >>

Patricia Tree Ethereum/wiki Wiki Github

Patricia Tree Ethereum/wiki Wiki Github

In a basic radix trie, every node looks as follows: Where i0 ... in represent the symbols of the alphabet (often binary or hex), value is the terminal value at the node, and the values in the i0 ... in slots are either NULL or pointers to (in our case, hashes of) other nodes. This forms a basic (key, value) store; for example, if you are interested in the value that is currently mapped to dog in the trie, you would first convert dog into letters of the alphabet (giving 64 6f 67), and then descend down the trie following that path until at the end of the path you read the value. That is, you would first look up the root hash in a flat key/value DB to find the root node of the trie (which is basically an array of keys to other nodes), use the value at index 6 as a key (and look it up in the flat key/value DB) to get the node one level down, then pick index 4 of that to lookup the next value, then pick index 6 of that, and so on, until, once you followed the path: root -> 6 -> 4 -> 6 -> 15 -> 6 -> 7, you look up the value of the node that you have and return the result. Note there is a difference between looking something up in the "trie" vs the underlying flat key/value "DB". They both define key/values arrangements, but the underlying DB can do a traditional 1 step lookup of a key, while looking up a key in the trie requires multiple underlying DB lookups to get to the final value as described above. To eliminate ambiguity, let's refer to the latter as a path. The update and delete operations for radix tries are simple, and can be defined roughly as follows: def update(node,path,value): if path == '': curnode = db.get(node) if node else [ NULL ] * 17 newnode = curnode.copy() newnode[-1] = value else: curnode = db.get(node) if node else [ NULL ] * 17 newnode = curnode.co Continue reading >>

State - Godoc

State - Godoc

Package state provides a caching layer atop the Ethereum state trie. type Account struct { Nonce uint64 Balance * big . Int Root common . Hash // merkle root of the storage trie CodeHash [] byte } Account is the Ethereum consensus representation of accounts.These objects are stored in the main account trie. type Database interface { // Accessing tries: // OpenTrie opens the main account trie. // OpenStorageTrie opens the storage trie of an account. OpenTrie(root common . Hash ) ( Trie , error ) OpenStorageTrie(addrHash, root common . Hash ) ( Trie , error ) // Accessing contract code: ContractCode(addrHash, codeHash common . Hash ) ([] byte , error ) ContractCodeSize(addrHash, codeHash common . Hash ) ( int , error ) // CopyTrie returns an independent copy of the given trie. CopyTrie( Trie ) Trie } Database wraps access to tries and contract code. type DumpAccount struct { Balance string `json:"balance"` Nonce uint64 `json:"nonce"` Root string `json:"root"` CodeHash string `json:"codeHash"` Code string `json:"code"` Storage map[ string ] string `json:"storage"`} GetNonce returns the canonical nonce for the managed or unmanaged account. Because GetNonce mutates the DB, we must take a write lock. func (ms * ManagedState ) RemoveNonce(addr common . Address , n uint64 ) RemoveNonce removed the nonce from the managed state and all future pending nonces func (ms * ManagedState ) SetNonce(addr common . Address , nonce uint64 ) SetNonce sets the new canonical nonce for the managed state func (ms * ManagedState ) SetState(statedb * StateDB ) SetState sets the backing layer of the managed state type NodeIterator struct { Hash common . Hash // Hash of the current entry being iterated (nil if not standalone) Parent common . Hash // Hash of the first full ancestor node (nil if curr Continue reading >>

State Tree Pruning - Ethereum Blog

State Tree Pruning - Ethereum Blog

One of the important issues that has been brought up over the course of the Olympic stress-net release is the large amount of data that clients are required to store; over little more than three months of operation, and particularly during the last month, the amount of data in each Ethereum clients blockchain folder has ballooned to an impressive 10-40 gigabytes, depending on which client you are using and whether or not compression is enabled. Although it is important to note that this is indeed a stress test scenario where users are incentivized to dump transactions on the blockchain paying only the free test-ether as a transaction fee, and transaction throughput levels are thus several times higher than Bitcoin, it is nevertheless a legitimate concern for users, who in many cases do not have hundreds of gigabytes to spare on storing other peoples transaction histories. First of all, let us begin by exploring why the current Ethereum client database is so large. Ethereum, unlike Bitcoin, has the property that every block contains something called the state root: the root hash of a specialized kind of Merkle tree which stores the entire state of the system: all account balances, contract storage, contract code and account nonces are inside. The purpose of this is simple: it allows a node given only the last block, together with some assurance that the last block actually is the most recent block, to synchronize with the blockchain extremely quickly without processing any historical transactions, by simply downloading the rest of the tree from nodes in the network (the proposed HashLookup wire protocol message will faciliate this), verifying that the tree is correct by checking that all of the hashes match up, and then proceeding from there. In a fully decentralized co Continue reading >>

Quorum And Constellation

Quorum And Constellation

Two projects Ive been working on for the past year: Quorum , written in Go, is a fork of Ethereum (geth) developed in partnership with Ethlab ( Jeff Wilcke , Bas van Kervel , et al) with some major changes: Transactions can be marked private. Private transactions go on the same public blockchain, but contain nothing but a SHA-3-512 digest of encrypted payloads that were exchanged between the relevant peers. Only the peers who have and can decrypt that payload will execute the real contracts of the transaction, while others will ignore it. This achieves the interesting property that transaction contents are still sealed in the blockchains history, but are known only to the relevant peers. Because not every peer executes every private transaction, a separate, private state Patricia Merkle trie was added. Mutations caused by private transactions affect the state in the private trie, while public transactions affect the public trie. The public state continues to be validated as expected, but the private state has no validation. (In the future, wed like to have the peers verify shared private contract states.) Two new consensus algorithms were added to supplant Proof-of-Work (PoW): QuorumChain, developed by Ethlab: a customizable, smart contract-based voting mechanism; as well as a Raft-based consensus mechanism, developed by Brian Schroeder and Joel Burget , which is based on the Raft implementation in etcd. (Neither of these are hardened/byzantine fault tolerant, but we hope to add a BFT alternative soon.) Peering and synchronization between nodes can be restricted to a known list of peers. Constellation , written in Haskell, is a daemon which implements a simple peer-to-peer network. Nodes on the network are each the authoritative destination for some number of public ke 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 >>

An Introduction To Ethereum And Smart Contracts: A Programmable Blockchain

An Introduction To Ethereum And Smart Contracts: A Programmable Blockchain

An Introduction to Ethereum and Smart Contracts: a Programmable Blockchain Bitcoin took the world by surprise in the year 2009 and popularized the idea of decentralized secure monetary transactions. The concepts behind it, however, can be extended to much more than just digital currencies. Ethereum attempts to do that, marrying the power of decentralized transactions with a Turing-complete contract system. In this post we will take a closer look at how Ethereum works and what makes it different from Bitcoin and other blockchains. Read on! In our previous post , we took a closer look at what blockchains are and how they help in making distributed, verifiable transactions a possibility. Our main example was Bitcoin: the world's most popular cryptocurrency. Millions of dollars, in the form of bitcoins, are traded each day, making Bitcoin one of the most prominent examples of the viability of the blockchain concept. Have you ever found yourself asking this question: "what would happen if the provider of this service or application disappeared?" If you have, then learning about Ethereum can make a big difference for you. Ethereum is a platform to run decentralized applications: applications that do not rely on any central server. In this post we will explore how Ethereum works and build a simple PoC application related to authentication. A blockchain is a distributed, verifiable datastore. It works by marrying public-key cryptography with the nobel concept of the proof-of-work. Each transaction in the blockchain is signed by the rightful owner of the resource being traded in the transaction. When new coins (resources) are created they are assigned to an owner. This owner, in turn, can prepare new transactions that send those coins to others by simply embedding the new owner Continue reading >>

Ipfs Parity Tech Documentation

Ipfs Parity Tech Documentation

Please subscribe to #4172 for more details on Paritys implementation progress. The eth-ipfs-bridge project allows early testing of the IPFS-implementation in Parity: kumavis/ipfs-eth-bridge This allows anyone on the network to access Ethereum objects by their canonical hash as encoded by CIDs: See also the explore-ethereum examples provided by js-ipfs: ipfs/js-ipfs/examples/explore-ethereum-blockchain The IPFS HTTP API is disabled by default. Enable it with --ipfs-api to expose it to localhost:5001. --ipfs-api Enable IPFS-compatible HTTP API. (default: false) --ipfs-api-port PORT Configure on which port the IPFS HTTP API should listen. (default: 5001) --ipfs-api-interface IP Specify the hostname portion of the IPFS API server, IP should be an interface's IP address or local. (default: local) --ipfs-api-cors URL Specify CORS header for IPFS API responses. (default: None) --ipfs-api-hosts HOSTS List of allowed Host header values. This option will validate the Host header sent by the browser, it is additional security against some attack vectors. Special options: "all", "none" (default: none). Continue reading >>

Vm Tests Ethereum Homestead 0.1 Documentation

Vm Tests Ethereum Homestead 0.1 Documentation

currentCoinbase: The current blocks coinbase address, to be returned by the COINBASE instruction. currentDifficulty: The current blocks difficulty, to be returned by the DIFFICULTY instruction. currentGasLimit: The current blocks gas limit. currentNumber: The current blocks number. currentTimestamp: The current blocks timestamp. address: The address of the account under which the code is executing, to be returned by the ADDRESS instruction. origin: The address of the executions origin, to be returned by the ORIGIN instruction. caller: The address of the executions caller, to be returned by the CALLER instruction. value: The value of the call (or the endowment of the create), to be returned by the CALLVALUE instruction. data: The input data passed to the execution, as used by the CALLDATA... instructions. Given as an array of byte values. See $DATA_ARRAY. code: The actual code that should be executed on the VM (not the one stored in the state(address)) . See $DATA_ARRAY. gasPrice: The price of gas for the transaction, as used by the GASPRICE instruction. gas: The total amount of gas available for the execution, as would be returned by the GAS instruction were it be executed first. The pre and post sections each have the same format of a mapping between addresses and accounts. Each account has the format: code: The body code of the account, given as an array of byte values. See $DATA_ARRAY. storage: The accounts storage, given as a mapping of keys to values. For key used notion of string as digital or hex number e.g: "1200" or "0x04B0" For values used $DATA_ARRAY. The callcreates section details each CALL or CREATE instruction that has been executed. It is an array of maps with keys: data: An array of bytes specifying the data with which the CALL or CREATE operation was Continue reading >>

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