BIP91 & SegWit2x Lock-in, Activation

There seems to be a lot of confusion about BIP91, SegWit, SegWit2x timelines lock-in and activation dates. This is a quick explainer. BIP91 Explained BIP91 Forces signalling for BIP141. 269/336 blocks are required to lock BIP91 in. Current BIP91 period started at block 476448. If at block 476783 we have 269 blocks that signalled bit 4, then bip91 will be locked-in. Once that (lock-in) happens BIP91 will be activated 336 blocks later (roughly two and one third of a day). BIP91-enabled nodes will reject blocks that do not signal BIP141. BIP91 was devised to avoid BIP148 activation. Once signaling BIP141 becomes “mandatory” we still need to have enough votes for BIP141 to lock it in and activate it. Lock-in happens after

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Sidechains: Alpha Sidechain Tutorial

In this tutorial we will take a practical look at sidechains [1]. We will concentrate on the Elements project [2] and its first sidechain known as Alpha . Alpha is a developer sidechain that is pegged to Bitcoin’s testnet [3]. In order to play around with sidechains in general and with Alpha in particular we need to have the mainchain installed on our machine. The mainchain in our case is the bitcoin testnet. Then we will need to install the Alpha sidechain. Let’s proceed. The instructions below are for Linux Ubuntu. Step 1 – Install bitcoind & alphad First we need to get some dependencies:

If you do not have git installed on your machine:

To be organized

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Bitcoin & Blockchain Programming #006 – Blockchain Notary System Design

by Albert Szmigielski Notary System Let’s design a notary system. A system that can notarize a document and store it. There are three solutions possible: a decentralized one, that can keep functioning for ever, a centralized system that would depend on a company running it, and a combination of both. We would like the system to be decentralized, so that in the event of our company’s demise the system can keep on functioning. This is a desirable property to have as wills may need to exist for decades before they are executed. In addition to this we will have a centralized component where we keep the information stored for our users. Added functionality like storing authorized users able to access

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Rootstock – Smart Contracts on the Bitcoin Blockchain

by Albert Szmigielski As a concept the Rootstock [1] platform is one of those ideas that once it is proposed it is obvious that it is a great idea. Essentially Rootstock aims to be what Ethereum is, a decentralized, Turing-complete smart contract platform. However, Rootstock aims to utilize the Bitcoin ecosystem rather than creating a new one from scratch. The way this will be accomplished is via the still not fully implemented sidechains technology [2]. This approach presents both advantages, and its own set of challenges. We will briefly outline what the Rootstock platform promises to offer and then will discuss the main points of the proposal. Smart Contract Platform Smart contracts are an active area of interest and research.

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New Book Review: Bitcoin and Cryptocurrency Technologies

For anyone serious about understanding the technical inner workings of Bitcoin, Princeton University Press will be releasing a new textbook later this year: Bitcoin and Cryptocurrency Technologies. After studying this book and doing the exercises, you will understand how Bitcoin works in detail, and see why there is so much commercial interest surrounding blockchain technology, not to mention the potential social and political ramifications. This book is both technically rigorous and very accessible—an indispensable reference for any serious student of cryptocurrencies. CryptoIQ’s very own Research Director, Albert Szmigielski, is mentioned in the Introduction for his help in reviewing the text. A free draft version of the book is available here. Check it out! -Paul Jones

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Compiling Bitcoin Classic from Source on Ubuntu

by Albert Szmigielski If you would like to run Bitcoin Classic and you want to build it from source here is the way to do it. In your terminal navigate to the directory you want Bitcoin Classic to reside in. Then clone the GitHub repository:

cd into the Bitcoin classic directory

checkout the branch with 2MB support

Now run the autogen, and configure scripts

If any of the dependencies are missing then configure will let you know, install the dependencies (see below) and try again from ./configure If all the dependencies are met you can now build (this will take a few minutes)

optionally you can also install

If all the dependencies were met

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Bitcoin: The Maximum Block Size Debate, Much Ado About Nothing?

Headlines Can Deceive News headlines can be like movie trailers. Too short to give an accurate picture of the full story—designed to grab attention and often deceptive. This article will explain in layman’s terms the issues surrounding one of the hottest Bitcoin * topics of late, known as “the maximum block size debate”. There is a lot of confusion swirling around the media. For those lacking insight into the mechanics of Bitcoin, simply scanning headlines can leave a misinformed impression. Mike Hearn, a former core developer, recently created major commotion with his blog post titled, The resolution of the Bitcoin experiment [1]. His post was followed by a prominent article in the New York Times, sounding a premature death knell

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Bitcoin Block Size Debate – Two sides to each coin.

by Albert Szmigielski As Bitcoin, the secure network and bitcoin, the currency gain in popularity, the number of transactions per time frame, and therefore per block increases. There is a limit to the number of transactions that can be included in a block. As the number of transactions is trending upwards, we are approaching the 1MB per block limit. A natural reaction would be to shrug and say: “so what, just raise the limit, problem solved”. However raising the limit has consequences on the economics of the network. Conversely, not changing the limit presents a different set of consequences. What follows is a summary and a review of arguments for and against the block size increase. Those in favour. The

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Bitcoin & Blockchain Programming #001 – Introduction

By Albert Szmigielski It has come to our attention that there is a shortage of Bitcoin and Blockchain programmers. As a result we have decided to post a series of tutorials starting at the very beginning. We will download and set-up a full Bitcoin wallet and then we will proceed to go through all the commands and how to use them. We will show you how to connect to your wallet programmatically via RPC calls (Remote Procedure Calls) , and finally we will put together a couple of projects using the material we have covered. We will work in Linux, for Windows users we will show you how to install a Virtual Machine (VM) so you can run Linux on

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Bitcoin Basics #003 – Bitcoin Wallets

By Albert Szmigielski Today we will explain Bitcoin Wallets A Bitcoin Wallet is a piece of software that allows you to do the following: Keep track of the bitcoins you own Send and receive bitcoins Connect to and query the Bitcoin network for a variety of information Technically the term wallet is a little bit misleading, the Bitcoin wallet does not hold your bitcoins. All the bitcoins ever created are stored on the blockchain. The wallet stores your private keys, which in turn allow you access to the bitcoins you own on the blockchain. There are a few types of wallets: Full wallet Light wallet (sometimes called a light  or thin client) Mobile wallets Web wallets Paper wallets Hardware wallets

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Milestone: The Bitcoin Network Reaches One Exahash

By Albert Szmigielski Sometime around January 24th 2016 the Bitcoin Network reached one Exahash per second for the first time ever. That is 1 quintillion, a 1 followed by 18 zeros or 1018 hashes per second. That is just an insane amount of computing power. Image: Bitcoin Network reaches ONE exahash. Image courtesy of Over the last two years the Bitcoin Network hashrate increased roughly 50-fold. Image: Bitcoin Hashrate over the past two years. Image courtesy of Why is this a big deal? Bitcoin currently has the most secure network in the world. To duplicate the network it would take a lot of resources. At a low price of $150 per Terahash, it would cost approximately $150 million

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Bitcoin blocksize increase discussion – summary and analysis of proposals.

by Albert Szmigielski Introduction Currently Bitcoin blocks are limited to 1 MB. This limit implies a certain number of transactions per time frame. Bitcoin blocks are found on average every 10 minutes, therefore on average we can expect 7 transactions per second. In order to compete with established companies, Bitcoin must scale up and therefore increase the blocksize to allow more transactions per time frame. Increasing the blocksize would require a hard fork. Anytime major changes are required to the Bitcoin protocol different interest groups raise their concerns and lobby for their interest. Proposals There were four proposals for increasing the blocksize put forward. They can be found in BIPs 100 through 103, and BIPs 105, 106, the unofficial 248,

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