Obfuscation for puzzles...

Obfuscation, the art of hiding things in plain sight, is a key part of designing puzzles. Here's one useful example that is much more complex than it might at first appear to be...

Photo by Vishnu Mohanan on Unsplash

Seven Segment Displays

In the 21st Century, LCDs, OLDs and all sort of other sophisticated display technologies make it increasingly easy to provide alphanumeric (or beyond) indications to users. But, some older display technologies still get used, for any number of reasons - from nostalgia to retro-design to simply saving space to pure perversity, and more. 

One such display (nostalgia, not perversity) is the 'Seven Segment' display. Seven LEDs arranged in a figure of '8' shape, and which can display all of the numbers from 0 to 9 by turning on some of the LEDs, or all of them for an '8'. The number '8' is a special humber in some cultures, and in electronics, displaying the number '8' causes the highest current consumption in seven segment displays! 

But seven segment displays can also display more than just the numbers - and this ignores the decimal point or full stop or period LED that is sometimes available to the left or right of the seven LED segments. With a little imagination, the '5' could be a capital (upper case) 'S', the '0' could be a capital 'O', and so on. Requiring more stretching of the imagination, the '9' might be a raised 'g', the '2' might be a capital 'Z'... Just by using those seven segments as raw source material, then many other letters can be produced: capital letters like 'U' and 'P' and 'C', for example. Lower case letters like 't' and 'o' and 'b' and 'd' are okay, but some letters are more challenging. A capital 'Y' can be produced by turning off the top LED in a curly '9', for example. 

But some letters are just plain difficult to produce on a seven segment display. Examples include: M, m, W, w, X,x, e, Q, q, etc. This doesn't mean that they can't be 'expressed' on the display, it means that their appearance might not be immediately obvious. At which point, we have obfuscation.

Seven Segment Font

Preparing puzzles for online use, or the CAD files to enable conference badges or other physical objects, often requires a true type font (almost 'de facto' for many typographical purposes nowadays). But fonts based on seven segment displays aren't all that common...

So here's one based on the coding used on the Synthstrom Audible 'Deluge' groovebox, an amazing piece of musical technology that is part sequencer, part synthesizer, part drum machine, part sample, part DAW and part effects unit, plus a few other parts. For its display. it uses just four seven segment LEDs, plus a few other LEDs underneath buttons, as part of the user interface, with the seven segment displays used for text and numbers (which scroll across - thus increasing the effective width to arguably 'more than 4' characters). The Deluge also comes from New Zealand, which is sort of a link with the 'Kiki' in the picture at the start of this blog post!

From: https://github.com/weavermedia/deluge-led-font?fbclid=IwAR0dNTx0U0GPTNHxYrVkdm3UUlq4PMhSv-pJ7M8vC2LipziNfalnWS7d7mQ

As you can see, some of the problematic letters, like lower case 'a' and 'e' have just been turned into their upper case, capital alternative. But the 'M', 'W', 'K' and 'X' are very distinctive, because the lower and upper case are the same, but they are also difficult to read at first glance. Oooh! Obfuscation. 

Even more interestingly, some of the upper case (capital) letters are deliberately turned into lower case, even when an upper case exists. 'o' is an example - it is used for the upper case (capital) and lower case, even though a zero '0' could be used, although that might be confusing in some circumstances... Conversely, some are left as upper case, even when a lower case alternative exists: 'c' and 'u', and maybe 'j'.

But for puzzles, then a font like this is an almost perfect way of providing a mixture of familiarity and unfamiliarity, all at the same time. Careful choice of words enables clues and hints to be given in varying degrees of obscurity: 'CLUE' for example, is easy to read in the font, whilst 'MIX' is much harder at first glance.  

Yes, there are other 'seven segment' fonts, but this one has an electronic music connection, and is pretty distinctive, so it has huge appeal to me for use in puzzles. Curiously, some of the alternatives cheat by using more than seven segments!

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