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Smart Contracts News Monday, February 12

Smart Contracts News TLDR / Table of Contents

  • Predicting Random Numbers in Ethereum Smart Contracts
    • Ethereum has gained tremendous popularity as a platform for initial coin offerings (ICOs). However, it is used in more than just ERC20 tokens. Roulettes, lotteries, and card games can all be…
    • Ethereum blockchain, gas price, block variables, higher gas price, smart contracts
  • How Smart Contracts Can Improve Revenue Sharing in the 21st Century.
    • Revenue sharing is truly different in each industry, but at its core revenue sharing is sharing profits or losses among different groups or individuals. Although we may not always see it, the…
    • revenue sharing, smart contracts, , ,
  • How Formal Verification Can Ensure Flawless Smart Contracts
    • Bernhard Mueller, Security Engineer at ConsenSys, lays out how to eradicate errors in the Ethereum bytecode. Smart contract security is serious business. Previously, I wrote about detecting common…
    • state, Smart contract security, formal verification, Ethereum Virtual Machine, certain error states
  • Smart Contracts sicherer machen – mit Hyperledger Sawtooth
    • Hyperledger Sawtooth ist jetzt in Version 1.0 verfügbar. Wir haben mit Dan Middleton gesprochen, dem Projektmanager des Blockchain-Framework.
    • Sawtooth und Fabric, Unterschied zwischen Sawtooth, Dan Middleton Sawtooth, Sawtooth Betreuer kümmern, Anwendungen für Sawtooth

Score: 10111.773984220907
URL: https://blog.positive.com/predicting-random-numbers-in-ethereum-smart-contracts-e5358c6b8620?gi=afb2753801c4
Tweeted At: Sun Feb 11 20:48:10 +0000 2018
Publish Date: 2018-02-01T03:27:43.238000+00:00
Author: Arseny Reutov

  • We decided to research smart contracts in order to assess the security of PRNGs written in Solidity and to highlight common design antipatterns that lead to vulnerabilities allowing prediction of the future state.Our research was performed in the following steps:3,649 smart contracts were collected from etherscan.io and GitHub.These contracts were…
  • So if an attackers contract calls the victim contract via an internal message, the same PRNG in both contracts will yield the same outcome.Example 1 Won if block number is even// (note: this is a terrible source of randomness, please dont use this with real money)bool won = (block.number %…
  • In these contracts, the blockhash of the current block was deemed known at runtime and was used as a source of entropy.Example 1 deal(address player, uint8 cardNumber) internal returns (uint8) { uint b = block.number; uint timestamp = block.timestamp; return player, cardNumber, timestamp)) % 52);}Example 2 random(uint64 upper) public returns…
  • The random numbers for the two contracts will be the same.Example 1 random number between 0 maxuint256 constant private FACTOR = rand(uint max) constant private returns (uint256 result){ uint256 factor = FACTOR * 100 / max; uint256 lastBlockNumber = block.number – 1; uint256 hashVal = return uint256((uint256(hashVal) / factor)) %…
  • For instance, popular Ethereum client web3 has the API method web3.eth.getStorageAt(), which allows retrieving storage entries at the specified indices.Given this fact, it is trivial to extract the value of the private variable pointer from the contract storage and supply it as an argument to an exploit:function attack(address a, uint8…

Tags: Ethereum blockchain, gas price, block variables, higher gas price, smart contracts

Score: 123.1410071942446
URL: https://blog.rublix.io/how-smart-contracts-can-improve-revenue-sharing-in-the-21st-century-8a2294533efa?gi=e9e77a1d2bf3
Tweeted At: Wed Jan 31 05:53:53 +0000 2018
Publish Date: 2018-01-30T22:46:07.826000+00:00
Author: Rhys Boulanger

  • How Smart Contracts Can Improve Revenue Sharing in the 21stCentury.Revenue sharing is truly different in each industry, but at its core revenue sharing is sharing profits or losses among different groups or individuals.
  • The teams pool their annual revenue and redistribute it from high grossing team to low grossing ones.Small Business: Owners may choose to use incentives programs, like paying their partners a percentage-based bonus for referring new customers.Challenges With Our Current Revenue Sharing ModelWhen it comes to revenue sharing, there has been…
  • For example, when it comes to music streaming services who combine songs from different artists into one package, they face the issue of how much revenue to allocate to each song.Speedrevenue sharing is a process and in come cases, there is an order to which stakeholders receive their portion of…
  • Using smart contracts, we can ensure that all stakeholders receive their correct share of the revenue by embedding specific terms into a smart contract.For example, lets say you invested a certain amount of cryptocurrency for 15% ownership in a venture.
  • By using smart contracts, you can ensure that right when revenue starts to flow in, 15% of it will be transferred to you wallet in real time.As for speed, there is nothing quicker that the real time transaction mentioned above.

Tags: revenue sharing, smart contracts, , ,

Score: 11.716345160179126
URL: https://media.consensys.net/how-formal-verification-can-ensure-flawless-smart-contracts-cbda8ad99bd1?gi=38b23bf2aeaa
Tweeted At: Fri Feb 02 06:06:00 +0000 2018
Publish Date: 2018-01-29T05:23:20.610000+00:00
Author: Bernhard Mueller

  • Formal verification allows us to prove conclusively that certain error states can never occur.There is a considerable amount of academic research into semantic modeling of the Ethereum Virtual Machine (EVM) and formal verification of smart contracts using various frameworks (links below).
  • In this article, Ill describe an approach based on symbolic execution and the Z3 theorem prover, and demonstrate that this method is capable of detecting subtle bugs, such as those resulting from Solidity memory addressing mechanics.Our specimen of choice is Ownable, a commonly used base contract that defines the owner…
  • Each state consists of a set of concrete and/or symbolic values associated with the contract account (storage, balance,… ) and virtual machine environment (program counter, call data, etc.), as well as a set of path constraints, i.e. the requirements that must be fulfilled to reach that particular state.Mythrils symbolic execution…
  • We can therefore more easily obtain the set of relevant initial states by selecting from all pairs of global state and machine state (, ) where:An error state exists if it is possible to satisfy the logical formula:In plain English, we attempt to prove that it is impossible to reach…
  • /analysis.py Ownable.solAnalysis completed.Since no counterexample has been found, we can conclude that Ownable is safe with respect to modifications of the owner state variable, with a few caveats:We assume that the Ethereum virtual machine always behaves correctly;The result only applies to the Ownable contract in isolation, not necessarily to contracts…

Tags: state, Smart contract security, formal verification, Ethereum Virtual Machine, certain error states

Score: 0
URL: https://jaxenter.de/smart-contrats-hyperledger-sawtooth-67050
Tweeted At: Mon Feb 12 13:43:21 +0000 2018
Publish Date: 2018-02-12T14:41:07+00:00
Author: Gabriela Motroc

  • JAXenter: Eine einzigartige Eigenschaft von Hyperledger Sawtooth ist, dass man Smart Contracts in seiner Lieblingssprache programmieren kann.
  • Ihr untersttzt etwa Go, JavaScript und Python, um nur ein paar zu nennen.
  • Ist Go eine gute Sprache, um Smart Contracts zu programmieren oder Blockchains zu erstellen?
  • Natrlich, es gibt in allen Projekten Bugs und wir werden diese auch in Sawtooth finden und beheben, aber der Groteil der Arbeit aus der Community in den letzten Monaten hat darauf abgezielt, die Plattform abzuhrten und zur Reife zu bringen.
  • Unternehmen knnen also ruhigen Gewissens auf dem API aufbauen, da zuknftige Verbesserungen und Fixes rckwrtskompatibel sein werden.

Tags: Sawtooth und Fabric, Unterschied zwischen Sawtooth, Dan Middleton Sawtooth, Sawtooth Betreuer kümmern, Anwendungen für Sawtooth

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