Frequency Analysis

https://en.wikibooks.org/wiki/Cryptography/Frequency_analysis

A friend of mine recently released a demo for his new studio’s second title, Heartbound[1], though aside from being a fantastic developer, his cryptographic prowess has secured him multiple DefCon Black Badges[2][3].

Along with the release of the game, he created an ARG puzzle that you can check out here: http://gopiratesoftware.com/games/Heartbound/TheLightBeckons/
Spoiler Warning: If you’d like to work through the challenges yourself, I’d avoid reading the rest of this article.

One of the challenges requires the usage of the runic glyphs as seen on multiple pages throughout the ARG, though I wasn’t sure as to how I would actually apply them.

My initial thoughts lead me to believe it was simply a public font and many hours of googling resulted in even more confusion.

A series of books titled “Our Mathematical World” recently launched here in the UK. One of the cryptography-focused issues brought up the usage of frequency analysis to decode caesar ciphers along with unknown foreign text, at which point I  immediately thought back to the puzzle. The book even provided this neat little table:

We’ll start off with this sample of all glyphs and start searching for the most frequent ‘characters’. To narrow this down further, we can check the glyph positions and reference them with letterfrequency.org.

The site identifies the most common first letter in the English language as ‘T’. Under this assumption, I went with what I’ve coined as the ‘table’ glyph. I’ve removed the background and marked our guess.
Luckily there are a couple of two letter words on the right set of glyphs, this makes it easier to narrow down possible characters.
The most common second letters are as follows: h, o, e, i, a, u, n, r, t. As, at least to my knowledge, ‘th’ isn’t a word, we can assume that the F glyph is ‘o’ to form ‘To’.

From here it’s a case of following similar cases as well as using word finder tools to aid in character assumptions. I’ve also added a key as to help us form words later on.

‘th’ being by far the most common two letter combination made eyeing up certain words / assumptions much easier, providing a larger sample size for future referencing. Infuriatingly there isn’t enough data to complete a custom alphabet, much to the dismay inner completionist.

It was a super fun topic to look into, though these days frequency analysis has lost most of its purpose in the realm of cryptography, only bearing relevance to the odd archaeologist or computer science class.

Bonus! My original messy walkthrough of the puzzle

Sources:
[1]: www.gopiratesoftware.com/games/Heartbound/
[2]: http://potatohatsecurity.tumblr.com/post/94565729529/defcon-22-badge-challenge-walkthrough
[3]: http://potatohatsecurity.tumblr.com/post/126411303994/defcon-23-badge-challenge

1 Comment

  1. Smithf28 March 23, 2017 at 6:59 am

    Nice read, I just passed this onto a friend who was doing some research on that. And he just bought me lunch since I found it for him smile So let me rephrase that Thank you for lunch!

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