Summary of AES-CMAC

CMAC creates a message authentication code from an encryption primitive. The most common is the AES-CMAC, which is described fully in RFC 4493. It involves operating the AES operation in cipher-block chaining mode, where each 16-byte chunk of the original plaintext is fed to the AES encryption operation in turn and combined with the output… Continue reading Summary of AES-CMAC

Power side-channel attack on AES-CMAC

AES-CMAC is a popular message authentication code in the automotive world. Although I have been working in automotive electronics for 25 years, I don’t know the actual reason why. But my surmise is that this stems from the fact that the first cryptographic accelerators used in automotive met the “Secure Hardware Extensions” (SHE) specification, which… Continue reading Power side-channel attack on AES-CMAC

RIP Sir Clive Sinclair

A hero of the early home computing era, Sir Clive Sinclair, died on 15th September 2021. Sir Clive was a diverse inventor, way ahead of his time. The portable TV, at the time scoffed at – “you can’t watch TV on the move” – now a commonplace activity. His battery-powered trike was really just waiting… Continue reading RIP Sir Clive Sinclair

ISO/SAE 21434 is ready

Binary ghost

This standard for road-vehicles cybersecurity engineering finally sees the light of day. It was developed under both the International Standards Organisation and the Society of Automotive Engineers, after a lot of hard work from many contributors across the industry. The standard gives a framework within which designers of vehicles, and the electronic control units within… Continue reading ISO/SAE 21434 is ready

What is an embedded system?

I just wrote a post for an Infosec site, discussing some definitions of embedded systems. I survey some existing definitions, describe why I don’t feel they represent the current state of embedded systems, and offer another: “It’s an embedded system if the end-user doesn’t control the code that it runs”. Once an end user takes… Continue reading What is an embedded system?

Me: One, Tiny pieces of plastic: Nil

For want of a better place to log how to get at the dishwasher pump *next* time it gets stuck with a tiny piece of plastic blocking the impeller, I’m sticking it here.

In case it helps anyone else it’s a Bosch Classixx (no idea what model no, bought about 2004 IIRC). Here are the steps:

EEWeb electronic design site

I recently became aware of the [EEWeb]( electronic design site (as one of their reps emailed me to see if I’d like my site to appear on their front page… we’ll see if my server can handle that soon!)

It’s sponsored by [Digikey](http://digikeycom/), much like [RS](’s [DesignSpark]( and [Farnell](’s [element14](

There’s an awful lot of content and I’ve barely scratched through a tiny bit of it – worth a trawl!

Variables and signals in VHDL – and when variables are better

VHDL has two types of what-would-normally-be-called-variables:

* `signal`s, which must be used for inter-process communication, and can be used for process-local storage
* `variable`s which are local to a process.

(there’s also variables of a `protected type` which we’ll ignore for now as they’re another thing altogether)