Reader challenge explained

As I promised, here's a brief explanation of the reader challenge I posted earlier. (Deadlines in the summer? Baaad idea.) I will leave decoding as homework though.

Spoiler alert!

I. Almost trivial

This is a simple substitution cipher using my haxor handle (repeated characters removed) as the key:


Reversal is almost trivial due to the distinct pattern it leaves in the letter frequency spectrum. "Almost", because there is an added challenge in the language used.

II. Shouldn't be very hard either

This message was transformed into audio with the Hellschreiber teleprinter. There's no further encryption. Some people noticed that there's a hint in the audio metadata; this was unintentional.

III. Might take some effort

A visual encryption scheme. A message is encoded in the difference of these two random dot patterns. I tried to add noise into the encoded message to make the resulting similarities in the patterns less obvious to the eye.

IV. NSA-grade

Okay, it's not really NSA-grade. But it's a Playfair cipher, using the following key:

$square =

Whitespaces and punctuation was removed, and full stops were converted to "STOP".

I was surprised at how many people actually reversed this!


  1. Thank you!

    I am sad I didn't think of the old english language when gluing scripts to do letter frequency analysis :)

  2. Oona, thanks for putting together this little challenge! I had fun figuring these out, and learned some things along the way as well.

    1. Agreed...I had a lot of fun trying to figure these out.

  3. Thank you.

    I have taken this as a wonder journey:


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