I do feel a bit like in that picture, to be honest. These past few days I have started doing my first audit in code4rena and together with the Smart Contract course and my job it’s quite a lot to handle.



Yes, mainly because I did pay for it. But that only helped me take it even more serious.

And then, a week ago I left my “fear” of not being prepared aside and I registered in code4rena, determined to participate in the next auditing contest. And so I did. A couple of days after that, the as



Firstly, I am going to help you understand in a simple way what is a reentrancy attack and how you can prevent it, and then, I will dive deeper into code examples in order to show where are the vulnerabilities, what would be the attacker code and most importantly I will show you the latest verified methods to protect not only one but all the smart contracts in your project.

Spoiler: If you have already heard about the nonReentrant() modifier, keep reading because you are about to discover a



When I first discovered Blockchain and started to read about the potential that it has and how much certainly present is going to be a big thing in the near future I wanted to tell everyone about it and I found myself in a situation where I was not even able to explain what it is and what is it applied to.

“Blockchain is the new internet” — I was saying.

Okay, but tell me more about it, sounds interesting

“The internet will be decentralized thanks to this new technology” — I was mentioning



You might have come across some Solidity tips to improve your code skills in order to save some gas, but, today I want to focus more on how understanding the Ethereum Virtual Machine can effectively save you gas costs on your smart contracts.

Since we are going to dive into Ethereum, I am going to leave here the snippet of its Yellow Paper which specifies the gas costs of the opcodes, and during the article we will be referring to them.



Tip #1: Cold access VS warm access

Gcoldsload: 210

To start, let me mention I am a Software Engineer in Test, aka QA. I have been working on testing mobile apps and writing some automated tests for over 7 years.

Now, how does a QA end up involved in the world of Blockchain?

Was it through Bitcoin? or Trading? or any kind of crypto investment? Not even close. I have never been interested or involved in anything related to crypto. And I will tell you more I had never even heard the word Blockchain until the day I caught up with a good old friend