Introduction to Cryptographic Hash Functions for the Working Developer

Much more than encryption algorithms, one-way hash functions are the workhouses of modern cryptography - Bruce schneier

This post would be a quick, straight to the point, overview of some essential things a developer should know about cryptographic hash functions. It is targeted at the working developer who needs to be familiar enough with cryptographic hash functions in order to use them, but who does not need to know the gory details of how they are implemented, all their possible use cases or how they work internally.

This post contains the following sections:

1. Cryptographic hash function: A definition
2. Properties of cryptographic hash functions.
3. Types of hash functions
1. Fixed length hash Functions
2.  Extendable Output Functions (XOF)
3. Password hashing functions 
4. Some Hashing Hygiene

NFTs are not to blame

T206 Honus Wagner baseball card sold for $6.606 million just this August 2021, Pikachu Illustrator, a pokeman card sold for $195,000 in 2019. You can get different Micheal Jordan's basketball card on e-bay ranging from couple of thousands to couple of millions. Sentimental and collectible items have always been part of the human experience. NFTs are not to blame.

Why should pieces of cards with pictures of athletes (or game characters) be worth that much? Why should JPEGs/PNGs be worth that much? Maybe because humans also value things for sentimental reasons just as they do for utilitarian/sustenance reasons.

NFTs only made the act of ownership that was so easy to establish in the physical realm, also possible in the digital realm. It's only natural it will be used for digital arts/collectible culture.

The mistake to avoid, is thinking NFTs are only about digital arts and collectibles. No! they are more than this. The ability to create unique, non fungible digital items that can be provable owned, can be, and is being deployed for other use cases.

Why I am offering NFTs as a crowdfunding perk

Non-equity funding campaigns are always based on promises: "Back us now, and we promise you early access to the product when we launch, or we promise you a discount, digital shout-out or swags". I am currently running an Indiegogo campaign where the promise will also include an NFT: Non Fungible Token, which is a digital artifact that can be used to prove things like ownership. This, as far as I know, is the first time NFTs would be used in this capacity.

In this post, I will shed some light on what NFTs are and share my thoughts on why they are a  perfect perk for a non-equity crowdfunding campaign. In doing so, I will touch on my thoughts on the continual march towards the digitalization of the human experience. How digitalization and technologies like virtual/augmented reality, blockchain technology, etc are making it possible to further digitize aspects of society and human interaction that were previously rife with problems or just plain impossible to digitize.

By the way, my campaign is to kickstart the development of DishAfrik: a recipe app to discover, enjoy and share African recipes. Think of it as Yummly or Tasty.co but focused on African cuisine. One of the perks of the campaign is going to be 54 uniquely generated collages made up of 54 recipes from 54 countries. 54 because currently Africa is home to 54 fully recognised sovereign states.

You should check out the IndieGoGo campaign and back the project :) Find it here 

TL;dr 

• Ever since the third industrial revolution, there has been a march towards digitalization of the physical world. 
• Blockchain-related technologies, like NFTs, provided the possibility to digitize aspects of the physical world that relied on scarcity, uniqueness, and proof of ownership, aspects that were previously hard to digitize. 
• DishAfrik's Indiegogo campaign will be making use of NFTs as a perk, using it as a way to capture participation, while also creating digital art in the form of a recipe collage that can also be owned.

Understanding the Magic behind Utility Types in TypeScript

This post will be the conlcuding post in the Introduction to Advanced Types in TypeScript series. It looks at some of the utility Types in TypeScript, explain how it works while pointing out the features within the TypeScript type system that makes it possible.

Why TypeScript?

TypeScript comes with a powerful and expressive type system. Its expressiveness makes it a joy to work with while its powerful features makes it possible to build, and scale large codebases by providing type safety.

One of the ways TypeScript brings about type safety is by providing developers the tool to manipulate types in ways that encode constraints within the type system. This then ensures that code that could lead to runtime exception do not compile, making it possible to catch errors during development time and not in production. One of such tools TypeScript provides for this are Utility Types.

Utility Types are a set of Generic Types that come natively within TypeScript that makes it possible to transform one type into another. This sort of type transformation is useful because it makes it possible to take exiting types, and apply modifications to it which would ensure the enforcement of certain constraints.

In this post, we would look at 2 of such Utility type and how they could be used to provide more type safety. After that, we would take a step back to understand some of the other TypeScript features that come together to make Utility Types possible. Armed with this knowledge, we will then demystify Utility types by taking a peek under the hood of the 2 Utility types in focus to see how they are implemented.

First impressions with Deno from building PlanetTypeScript.com

PlanetTypeScript.com is a content aggregator for all things TypeScript. It regularly polls RSS feeds for TypeScript related content, which it then list on the site, send out as a tweet via @planetypescript, and also as a weekly digest to subscribers.

Back when I used to write a lot of Java-related content on this blog, I found out that my blog ended up on www.topjavablogs.com/, which is a site that aggregates Java contents. So when I decided to play around with Deno, I thought a nice little idea would be to build something similar to topjavablogs.com, but for TypeScript. And that is how PlanetTypescript.com was born.

In this post, I will share some of my first impressions with Deno. The things I enjoyed and the bits I found inconvenient. Let's start with the cool stuff.

3 Ways to Name Types in Typescript

TypeScript type's system is structural and hence, it allows for the easy creation of types based on the shape of data. These types can be created and used without having a name. For example:

let john: {name: string, age: number} = { 
  name: "John Doe", 
  age: 30
}

Where {name: string, age: number} is the type defined.

But there is a problem with using the type definition this way. If we want to create another person and annotate another variable with the type, we would need to repeat ourselves:

let john: {name: string, age: number} = {
  name: "John Doe", 
  age: 30
}

let jane: {name: string, age: number} = {
   name: "Jane Doe", 
   age: 45
}

This is not dry.

How to implement sleep function in JavaScript

Most popular mainstream languages have a sleep functionality that allows for the pausing of code execution for a specified amount of time. Not surprising this functionality is often implemented via a function usually named sleep. For example:

// ruby
sleep(time_secs)
// python
import time
time.sleep(time_secs)
// Java
Thread.sleep(time_milli_secs)
// Perl
sleep(time_secs)

JavaScript does not have a similar sleep function, although it has the setTimeout function which can be used to achieve a similar purpose. The only problem is, using setTimeout is not as convenient as one would like. This is due to the fact that setTimeout is an asynchronous function, hence one would have to continue the execution of the code, in the callback passed to it, after the elapsed time.

console.log("Executing code..."); 
setTimeout(() => { 
console.log("continue after pause"); 
}, 3000)

This is not convenient.

A more convenient option would be to have something similar to:

console.log("Executing code..."); 
// sleep for some time
// sleep()
console.log("continue after pause");

Unfortunately, this does not exist natively in JavaScript. But this is not to say we can't implement one!