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Aenigma Solve

· 6 Minuten Lesezeit
Anderson de Souza

Since my childhood, I’ve had a taste and a need for writing in code (so I could vent about my crushes without the risk of getting caught).

NEED?​

Since I didn't know another language yet—and even if I did, it wouldn't have served my purpose, as anyone who spoke it could still access my secrets—I quickly turned to something I didn't even have a name for at the time: a Monoalphabetic Substitution Cipher1.

'A' was a star, 'B' was a rune, the letter 'C' was a waxing moon, and so on.

And just like that, it was done. Now, all I had to do was copy the substitution table and give it to anyone I wanted to share my secrets with.

Back then, I had a crush on a gal, but as my family moved to another town, I needed to send her the letter 2 along with another one to my friend who acted as our go-between. Did I trust my friend? Yeah. So much so that we already had our own secret code, not to mention 'P-language' 3 for when we spoke. But there were some things only my crush was meant to read 4. All of this inside an envelope marked "SOCIAL LETTER" 5 with a 1-cent stamp, and more often than not, a handmade envelope.

In the last letter I got from my friend, she warned me that our pen-pan romance scheme had been busted: while trying to smuggle a letter inside te girl's arm sling, her parents noticed and found out everything. Well, at least the 'sensitive parts' weren't decoded. LMFAOOO

Challenge​

Years later (around age 16 or 17), a letter arrived at my place. "SENDER: GUESS WHO?" Boom. My friend had found me again. I wasn't completely shocked 'cause she had talked to my parents in person at a religious event, so she probably got my new address there. I'm not entirely sure if she handed the letter to my parents or if she asked for the address and mailed it.

At the end of the letter, there was an old-school ciphered message. Right after it, a cliffhanger: "You're going to have to reply to this letter so I can send you the code for you to understand the sentence! LOL"6

Man, that really triggered me. Back then, I hated being forced to do anything, and I was pretty determined to show off how smart I was (poor little being).

I grabbed a notebook and rewrote the entire sentence. Then, I wrote down the characters. I started brainstorming a method to crack it. "It's pure substitution, a silly swap. If someone made this up, I can crack it too!" - or so I thought.

The table didn't work out so well; a piece was missing. I grouped the words together and, using Portuguese grammar, started determining whether a given character could be a vowel or a consonant. I had to count on my friend having written with impeccable Portuguese, free of slang or typos; otherwise, it would cause inconsistencies in the method.

Back then, my simple line of reasoning went like this:

  • A word can start with a consonant, followed by another consonant or a vowel.
  • A word can start with a vowel, but it must be followed by a consonant (Aarão would beg to differ, haha).
  • A consonant can follow another consonant only if it is "H, L, N, or R."
  • The last character must be a VOWEL or one of the following consonants: "L, M, R, S, X, Z."

For every V/C (Vowel or Consonant) I placed under a character, I had to replicate it across all occurrences to ensure the consistency and efficiency of the method. In fact, the more words she had written, the more it would help me solve it.

These were the rules of my rudimentary cracking system, which, by the way, would only be effective specifically in the Portuguese language.

At the time, I had no knowledge of "Frequency Analysis" tools and techniques 7. But I had a problem to solve, the drive, and the capability.

After determining whether each character was a vowel or a consonant, I started assigning a letter to each symbol, rewriting the text and replacing all matches of that character: "The square could be a 'T'"...

Victory​

I kept at it, trial and error, until I finally managed to translate the sentence.

Right after that, I set about creating my own copy of the cipher dictionary, though naturally, a few letters were still missing.

I wrote a reply to my friend and just couldn't help but brag. Using her very own cipher, I told her it wouldn't be necessary to send me the answer key.

A few days later, I received a letter in pure disbelief, questioning how on earth I had managed to translate and replicate that secret code.

To this day, I still wonder: "What did Rafa actually think about that whole thing?"

Aenigma solve

Notes:​

  1. ↩

    • When I say I was born in a really great era, this is what I mean: having experienced sending paper letters, 4, 8, and 64-bit video games (and later, of course, the PS1), offline computers, dial-up internet (though I never actually used it), TDMA phones (my first cell phone was a Gradiente CD 550)—man, I even miss *3001#12345# (Field Test Mode) — and now living through things like A.I., V.R. (Meta Quest 3), and the modern internet.

    ↩

    • Well, as this article was originally written in Portuguese, it would be a hell of a trouble to explain this part in English. But I found something that could help English readers to understand: The "P-language" is something similar to "Pig Latin", "Gibberish", "Opish" and "Ubbi Dubbi".

    ↩

    • This part doesn't contribute much to the story; it's just a curious note about having practically dealt with the Byzantine Generals Problem, MitM (Man-in-the-Middle), cryptography, etc., in my own life back then.

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    • This was a hack I learned from a friend of my mother's, who was a former postal worker. All you had to do was write "CARTA SOCIAL" (Social Letter) and stay within the ONE-PAGE limit. Yes, they would actually weigh the envelope sometimes. Carta Social – Wikipedia, the free encyclopedia (Note: This was a specific low-cost postal service in Brazil).

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    • I need to track down the letter among my things so I can write the exact words used here.

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  7. ↩