How to run a Libra validator node yourself:

Everyone knows Facebook announced Libra, and its testnet. If you follow the instruction of it, you can run a client and connect to testnet, create account Alice and Bob, send 10 unit between them in 15 minutes.

This post is NOT about how to do that, this post is about how to run a local validator and connect your client to yourself.

If you look at the code structure, FB actually released a validator with it, it’s just undocumented (not talking about how to run it yourself). …


Centralized Payment System vs. Decentralized Payment System

In this post, we will take a closer look into payment systems. We will talk about what is a centralized payment system and then what is a decentralized payment system using blockchain technology. This post assume you understand what blockchain is and what a full node in bitcoin blockchain is.

First, what’s the current popular payment system and how does it work?

Let’s look at one example, VISA.

When processing a payment transaction, there are typically three main parties involved: the cardholder’s bank (whoever issue the card to customer), the settlement bank and…


Real use case of bitcoin — $12 lunch in Singapore.

So I was in Singapore this week, there is a cafe that I always wanted to visit, it’s called Ducatus Cafe Singapore. Finally got a chance to stop by. Apparently they have been around for a while, as the crypto market cool down, it doesn’t seems to impact them much. They still take all the popular crypto currencies for payment. In my case, I used BTC.

I ordered 1 Americano + 1 Latte with Caramel + 1 Duc Coinwich. The total cost is SGD 18. The waiter pulled out a…


Details about double spending attack during BCH fork.

We all know by now, there is a fork in BCH (Bitcoin Cash) on Thursday 2018–11–15.. 1542300000

Couple things to know before the hard fork, if you don’t know what is hard fork, read here. I also have a previous post about this hard fork. BCH-ABC and BCH-SV are the main 2 parties involved in the fork. ABC’s code base progress and coordination with other parties in the community was always one of the best, some of them was even better than bitcoin-core. This fork was also long planned many months ago…


About Bitcoin Cash coming November hard fork.

We all know by now, Bitcoin Cash will be hard forking by November 2018, if you don’t know what is hard fork, read here.

From the 2 clients source code, they both have this part in place:

//Bitcoin ABC code:
// Nov 15, 2018 hard fork
consensus.magneticAnomalyActivationTime = 1542300000;
//Bitcoin SV code:
// Nov 15, 2018 hard fork
consensus.magneticAnomalyActivationTime = 1542300000;

Before we dive into coding, some basic background information about Bitcoin Cash and different clients.

BCH (Bitcoin Cash) was a fork itself from BTC (Bitcoin Core), it’s the #4 biggest crypto by…


In the previous post, we talked about how to setup a test environment for bitcoin with docker containers. Each docker container runs a bitcoind process, it was on c++. We ran make command to build, went through the pain for long wait (or take our time to have a nice lunch). As most of modern web developer, pushing to production 20+ times a day is not unusual, wait 25 minutes between each small change is just not right. Now this post (Phase II) will solve all of that.

Jokes on the side, build-time is a big issue in developer’s day…


If you are new to bitcoins or docker , keep reading, this is for you.

What is bitcoin? Bitcoin (₿) is a cryptocurrency, a form of electronic cash. It is a decentralized digital currency without a central bank or single administrator that can be sent from user-to-user on the peer-to-peer bitcoin network without the need for intermediaries. For more technical details, read the wiki, or read the source code.

What is docker? Docker is a computer program that performs operating-system-level virtualization, also known as “containerization”. If you want to learn more about docker go read www.docker.com

If you are still…

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