A Byte of Coding Issue 370

Yo,

I met up for some cocktails and then dinner with two readers yesterday. It was a really great time! Thanks for coming out Colin and Andreas. I’ll definitely be looking to organize similar events in the future. Our conversations ranged from the frustrations of debugging issues in IoT devices (hardware vs software) to geopolitics (after a couple of drinks heh).

Anyway, here’s the issue.

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Unexplanations: sql is syntactic sugar for relational algebra

Published: 18 March 2024

Tags: sql, math, database

Jamie Brandon elucidates on how additions to sql (both features and optimizations) have made it inaccurate to consider it an exact representation of relational algebra.

Some highlights:

• “In database theory, relational algebra is a theory that uses algebraic structures for modeling data, and defining queries on it with a well founded semantics”

• scoping is where some of the largest differences are seen between real sql databases and theory

• “for most of the history of sql we did not know how to translate it to relational algebra, and now that we do know most databases still don't do it”

Reverse-engineering an encrypted IoT protocol

Published: 14 February 2024

Tags: iot, reverse engineering, infosec

Scott Leggett reverse engineers the encrypted protocol used by a solar panel smart meter, in order to capture metric data locally.

Some highlights:

• the device was not very secure

• you can use encryption and still not have a secure system

• leaving devices like this exposed on your home network can be risky business

What is MFA, and why does your app need it?

Published: 13 December 2023

Tags: sponsored, auth, web

WorkOS describes what multi-factor authentication (MFA) is and why it’s useful.

Some highlights:

• “it’s an added layer of security to your app that makes it more difficult for hackers or impersonators to steal and use a user’s credentials”

• describe the different types of MFA

• summarizes the back-end flow for different types of MFAs

10x Performance with SIMD Vectorized Code in C#/.NET

Published: 9 July 2023

Tags: c#, optimization, simd, cpu, dotnet

Alexandre Mutel takes on the challenge of “How to find efficiently a specified int from an int[] using x86-64 SIMD instructions ?“.

Some highlights:

• “One of the cool addition to .NET 7 are generic SIMD code via the namespace System.Runtime.Intrinsics that allows you to write SIMD code without dealing with specific CPU instructions, as long as the code stays simple and you can use the various existing methods available”

• process requires writing the SIMD code and checking the ASM code it generates

• stack spilling was the first performance issue tackled