So how do we create a decentralized oracle? The model is as follows: a contract should ask several oracles to execute the same query, get results from each oracle, and then determine the correct answer on its own based on multiple results (answers from multiple oracles).

External data to the smart contract (from outside the blockchain) can be provided only, as parameters (arguments) of its call. Oracles are software running outside the blockchain, which listens for "requests" by smart contracts for external data, and then provides this data to the smart contract, by calling the appropriate…

The recent news about 1400 bitcoins loss caused a lot of buzz: the amount of Bitcoins worth about 16.3 million $, not any kind of exchange hack, all happened using Electrum wallet - one of the oldest and still very popular Bitcoin wallet. I share the lessons which could be learned from that story.

With the new release of Hyperledger Fabric 2.0 the lifecycle of chaincode has been changed. It implies also the changes in the chaincode deployment process - what basically means that commands used to deploy chaincode in < 2.0 release (no matter if using peer binary or SDK) will not work. In this article I show how to deploy…

Truffle Suite is the tool pack dedicated to Ethereum developers (focusing on smart contracts). That very actively developed project is currently one of the most popular frameworks for implementing, testing and running Ethereum based decentralized applications. In this article: I will describe the Truffle Suite tools; I will…