Author: Michael Johnson

Summary: Erroneous implementation of BLOCKHASH can trigger a chain reorganisation leading to consensus problems Affected configurations: All geth versions up to 1.1.3 and 1.2.2. All eth versions prior to 1.0.0. Likelihood: Low Severity: Medium Impact: Medium Details: Both C++ (eth) and Go (geth) clients have an erroneous implementation of an edge case in the Ethereum virtual machine, specifically which chain the BLOCKHASH instruction uses for retrieving a block hash. This edge case is very unlikely to happen on a live network as it would only be triggered in certain types of chain reorganisations (a contract executing BLOCKHASH(N – 1) where…

London, United Kingdom, October 22nd – The Ethereum Foundation is pleased to announce the Keynote Speaker of Ethereum’s annual conference DΞVCON1, Nick Szabo. Nick’s keynote will focus on the history of the blockchain, smart contracts and assets on the blockchain. Nick is a computer scientist, legal scholar and cryptographer known for his research on digital contracts and digital currency. The phrase and concept of “smart contracts” was developed by Szabo with the intent of merging contract law into programming protocols on the Internet. Recently, Szabo contrasted the use of smart contracts on Ethereum in relation to the Bitcoin blockchain, “If…

London, United Kingdom, October 28th – Ethereum is happy to announce that Microsoft will sponsor and attend DΞVCON1, the premier Ethereum developer conference. Marley Gray, Director of Technology Strategy US Financial Services at Microsoft said, “Microsoft is excited to sponsor and attend Ethereum’s DevCon1. We find the Ethereum blockchain incredibly powerful and look forward to collaborating within the Ethereum Community. We see a future where the combination of Microsoft Azure and Ethereum can enable new innovative platforms like Blockchain-as-a-Service. This will serve as an inflection point to bring blockchain technology to enterprise clientele”. Ethereum founder Vitalik Buterin notes “DΞVCON1 is…

With DEVCON1 a mere week away, the teams are excited and preparing to share all the great tools and technology the ecosystem has to offer. There will be hundreds of developers and dozens of talks including Nick Szabo, Vitalik Buterin, and Marley Gray from Microsoft. Tickets are limited and we anticipate selling out, so if you haven’t already registered, head on over to https://devcon.ethereum.org to secure your spot now! cpp-ethereum TurboEthereum released 1.0.0 of the C++ tools. Work has been done on state trie pruning and upgrading network protocols (PV 62 & 63). Several Mix bugs have been fixed and…

One of the major security challenges of the internet over the last twenty years has consistently been the rather simple problem of securing user accounts. Right now, users have accounts with hundreds of websites, and dozens of passwords, leading to large numbers of hacks as individual websites, often run by people not particularly skilled in the finer points of cryptography and internet security, find themselves exploited by increasingly clever hackers, and users frequently deal with the complexity of remembering hundreds of passwords by either making them simple or making them all the same – with often very unfortunate results. Over…

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…

Special thanks to Vlad Zamfir for his work in developing many of the ideas behind prediction markets for content curation. For the past six years, people have been searching to try to find those elusive applications of blockchain technology that could finally break out into the mainstream. For cryptocurrency, the applications are largely already known – though it of course remains to be seen just how well it will be able to retain its advantages as traditional payment systems continue to become more efficient. But what about smart contracts and crypto 2.0? One route that we can take is to…

A lot of things have happened in the past few weeks in the Ethereum ecosystem, so many that it might be hard for a casual observer to understand where we are and what’s available out there. So I would like to use my first post here to give you an overview of the tools we’ve built and how you can use them to build interesting things right now. But first a short introduction: I am Alex Van de Sande and I am the lead designer on the Ethereum foundation. At DevconOne I gave a talk entitled “The Blockchain Versus The…

This is a second post on a series on how to use the current Ethereum tools to build smart contracts without needing programming experience. Download the latest version of the Ethereum Wallet, read the first part and let’s have fun! Creating a token is fun, but what is the value of a token that doesn’t do anything new? We are now going to create a new contract that uses the tokens we just created. The contract will be a Democratic organization that lives on the blockchain and that anyone holding a share token will be able to vote on proposals. So…

This is the third and final post on a series on how to use the Ethereum Wallet to create your own autonomous organisations. On the first post we detailed how to create a token, and on the second we shown how to generate a digital democracy controlled by these tokens. Now we will do the full circle and create a token controlled by the Organisation! We are going to modify the token contract to allow it to be minted by your DAO. So save the address of your current DAO in a note pad (pay attention to the icon) and…