John Graham-Cumming

Two-factor paper passwords

I guess it makes me boring but I try to get people to use stronger passwords. People love to use the same password over and over again, o...

Making a Ponyo boat

If you've seen the film Ponyo (or if you grew up in Asia) you may have seen a sort of toy boat powered by a very simple steam engine. This...

The UK has an entire IPv4 /8 that it isn't using

IMPORTANT UPDATES BELOW If you take a look at the list of IPv4 allocated /8 blocks there's one interesting block in there: 51.0.0.0/8 ...

Things I like about programming in Go

I recently wrote a blog post for CloudFlare about our use of Go . I thought it was worth following up with a bit more detail about why I li...

Rabbit hole: stumbling across two Portuguese punched cards

Look, here's the thing, I don't like mysteries that involve technology. I think I hate them because I know that some other human created the...

In praise of... text files and protocols

The other night I had to debug a problem where CMYK colors specified in an OmniGraffle file weren't making it into an exported PDF (or at...

Long range WiFi antenna from Illy coffee can

I have a stack of half finished projects that I'm trying to complete. Happily, the first one was finished late last night: a long range Wi...

UK government declines to pardon Alan Turing

There's been a petition to the government and an Early Day Motion asking for Alan Turing to be pardoned. This is something I oppose desp...

Lovelace's Leap

There's a great deal said about Ada, Countess of Lovelace that I find misguided. And, worse, the real intellectual triumph of Lovelace is ...

Beautiful Simplicity

GAGA-2

Last April I sent a weather balloon up into the stratosphere after months of preparation. You can read all the details starting here . I c...

"We've read your code"

Babbage's heart-warming message for the middle-aged

Please don't use pie charts

I don't like pie charts. I don't like them because they fail to convey information. They do that because people have a really hard time ju...

Who's your SSH buddy?

My foxhole radio

As a child I'd made a crystal radio set and had been meaning to make one again when I came across stories of foxhole or PoW radios made f...

Two ways to use an LED as a light sensor with Arduino

I needed to log when a light switched on and off during the night as part of debugging an oddly behaving movement sensor. To do that I built...

Your last name contains invalid characters

My last name is "Graham-Cumming". But here's a typical form response when I enter it: Does the web site have any idea how rude it is to cla...

To boldly go where Node man has gone before

With all the chatter about how uber-amazing Node.js is I figured I'd do a little comparison with my favorite language du jour: Go . Node'...

The lost world of physicality

The 10:10 Code

Four years ago I wrote about a way to encode the latitude and longitude of any point on the Earth's surface to 10m of accuracy with a 10 ch...

1,000 (bad) ideas

Tidying up my messy corner in the basement I unearthed one of my older "ideas books" in which I write down the random ideas that flit throug...

I Made a Rubbish Clock

With separate plastic, metal, paper, and glass recycling, composting, and pick up of all the rest, knowing which days to put out which bins ...

My primality testing code is faster than Sir Roger Penrose's

But, I guess he did win the Nobel Prize for Physics in 2020 so I can't really brag. However, it was a great surprise when looking at two pa...

Your test suite is trying to tell you something

A few weeks ago I started wondering about 'the test that occasionally and randomly breaks' in a large test suite at my job. The test, calle...

How to forcibly eject a CD/DVD from a MacBook Air USB SuperDrive

So you've got a DVD stuck in the external USB SuperDrive that connects to the MacBook Air? And you've tried hitting the magic Eject button ...

How I ended up with so much Hacker News karma

On the Hacker News leaderboard I'm currently in position #12 with 32,360 points. I was curious to find out how I ended up in that position...

Beware the Alan Turing fetish

Write your passwords down

Here's my advice on password security based on the collected opinions of others: 1. Write them down and keep them in your wallet because you...

Five bugs in a single line of JavaScript

Today I've been working with a piece of third-party software. I was having big problems getting it working and decided to delve into its ...