Blog Archives

ScytheCTF 2017 Writeup

I took part in the ScytheCTF 2017 capture-the-flag contest at It’s finished now, but the challenges should still be accessible in the practice area. Here are a few hints for anyone who needs them: optimize-me Not solved rsa-love Not

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3D noughts and crosses

3D Noughts and Crosses

Long ago (back in the 80’s), my school had a couple of Research Machines 380Z computers for us to play around on. These things had about as much processing power as your average modern-day wristwatch, but were great fun nonetheless.

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HackerRank W3 — where was everyone?

The latest HackerRank weekly challenge attracted 71 entries from the US and 387 from India, but only four from the UK. I think this is the lowest turnout so far. Maybe the good weather had something to do with it. But anyway,

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I recently learned about an encryption protocol called CipherSaber, which was developed in 2001 by author, consultant and Star Wars fan Arnold G. Reinhold in retaliation against government plans to restrict access to strong cryptographic techniques. CipherSaber is based on

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Subpixel-aware image scaling

Subpixel rendering is the technique your computer uses to make text on the screen as readable as possible even at small font sizes. In a typical LCD monitor, each pixel is represented by a combination of three separate light-emitting elements,

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Get notified when a website comes back online has been offline all evening. This is not such bad news, as there are other things I should really be doing right now. It would be nice, however, if my computer could let me know when the site comes

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Emergency kittens

Here’s a bookmarklet that replaces all the images on a page with kittens. To use, just drag it to your bookmarks bar and click when necessary. Emergency Kittens Update: I’ve edited the bookmarklet to work around an issue at

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Have you heard of HackerRank before? Their 20/20 Hack October programming contest launched a few hours ago. I just had a quick scan through the current leader board, and it looks like I’m the only Brit taking part in this thing so

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Dandelion clock

Here’s a dandelion clock I made using SVG’s built-in animation functions. Unlike every other SVG clock I’ve seen*, this one doesn’t use any Javascript at all. Instead, the hands are rotated by using <animateTransform> tags, and their starting positions are

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PHP malware

I was recently asked to quote for some work on the website of a business that delivers education-related services (I’m not naming any names here). To get an idea of the work involved, I asked for the FTP login details

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