Weekend workshop in NYC

Weekend workshop in NYC

The blockchain academy in NYC invited me to work with them on their teaching materials for developers, IT professionals and programmers. We also decided to take the opportunity to give few condensed workshops on smart contracts and Ethereum in NYC during the weekends. The next (and probably last) one will take place on Oct 21-22 in Rise New York, 43 W 23rd St. Chelsea. Here’s a video we’ve created after our previous session: For more details: https://www.theblockchainacademy.com/store/FBFKTG2t

Modifiers – Go With The Flow

Modifiers – Go With The Flow

What is a modifier Modifiers are a neat feature in Solidity that allows us to change the flow of our code execution. The modifiers (as the name suggest) can modify the code of a function. Look at the following contract: contract A{ uint public number; modifier zeroNum(){ number = 0; _; } function plusNumber(uint _input){ number = number + input; } } In the code above, the modifier zeroNum is executed right before the rest of the function. It reset…

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Ethereum developer Working environment

Ethereum developer Working environment

If you want to create smart contracts and dApps using Ethereum, you first must have a working environment. Here I’ll share with you my personal setup and why I choose to use it. The big picture Our working environment should contain three main components: Local Machine Keep it as light as possible 1.       Google Chrome (or Chromium for Linux users) 2.       MetaMask and/or Ethereum node of your choice 3.       Optional – SSH client and terminal Digital Ocean Droplet This is…

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Get your Bitcoin address using Ethereum smart contract

Get your Bitcoin address using Ethereum smart contract

Ethereum and Bitcoin are both using the same type of encryption, the ECC (Elliptic Curve Cryptography) over the same graph (256k1). While it’s not really recommended, the same key pair can be used both for Bitcoin and Ethereum. A simple Solidity code can be used to get the Bitcoin address of a public key. Such a code can run locally (as a constant function) on the Ethereum Virtual Machine to save gas, or as a regular Ethereum transaction. The code…

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Proof of data integrity – Solidity code

Proof of data integrity – Solidity code

Update: I’ve simplified to code to take more advantage of the boolean data type Ethereum offers. Now the mapping is (bytes32=>bool) instead of (bytes32=>bytes32). The boolean array is used to prove the existence of a single document. The root of the tree is stored once and is hashed again with the new input. The complete code can be found on Github. The old test files can be used on this code as well struct tree{ bytes32 root; mapping(bytes32=>bool) dataExist; }…

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How to be blockchain compatible. part one

How to be blockchain compatible. part one

Tl;dr: Don’t try to move your existing organization to be a “decentralized/ blockchain based” look at the cases in which your organization might implement some blockchain based solutions and start making the necessary changes in-house to allow future integration. Seeing how new technologies are changing our world, and change it fast, makes many entrepreneurs twist and itch. It’s in the blood of most of them to try and incorporate this new technology as soon as possible. However, most are failing…

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The blockchain developer path – Blockchain at Berkeley

The blockchain developer path – Blockchain at Berkeley

Mapping the blockchain education ecosystem When I created my first tutorials almost two years ago, there were very few educational resources about blockchains. The ecosystem was sorely lacking in good courses, tutorials and guides to ease the learning curve for newcomers. I remember the many days I’ve spent reading raw codes and technical documentation until I was finally able to manually connect to the Bitcoin network, create keys, sign transactions, etc. But two years is forever in the world of…

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The blockchain developer path – Princeton University – Bitcoin and Cryptocurrency Technologies

The blockchain developer path – Princeton University – Bitcoin and Cryptocurrency Technologies

Mapping the blockchain education ecosystem When I created my first tutorials almost two years ago, there were very few educational resources about blockchains. The ecosystem was sorely lacking in good courses, tutorials and guides to ease the learning curve for newcomers. I remember the many days I’ve spent reading raw codes and technical documentation until I was finally able to manually connect to the Bitcoin network, create keys, sign transactions, etc. But two years is forever in the world of…

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Certification, The ends justify the means.

Certification, The ends justify the means.

The wild west of certificates Blockchain education is a growing ecosystem with very few players. Most courses and training programs are trying to create their certification program, tailored specifically to their self-construct program. This is a major issue for anyone involved in this field: the students, the course/program instructors and creators and future employers/customers. My experience in this ecosystem has let me consider few approaches regarding certification, especially my eight weeks live course which provided me with numerous insights and made…

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ICO – Simple. Too simple.

ICO – Simple. Too simple.

important notice, please read! This post blog is for educational purposes only. Solidity and Ethereum are bleeding edge technologies and should be treated with respect. Make sure to properly educate yourself before attempting to implement any code you might find online. I can attest that the code provided here is without a doubt not secure. It’s (at the very least) susceptible to overflow attacks, short address attacks and transferFrom double spend attacks. This is actually a very good example to…

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