The Polybius Square is an uncomplicated cipher developed by the Greek scholar Polybius. Consisting of a 5x5 grid, each of the 25 letters of the Greek alphabet occupied a single square. With 26 letters, the English alphabet must be altered in order to fit a Polybius square. This is usually done by combining two letters, typically “I” and “J”, or by including the digits 0-9 on a 6x6 grid with 36 squares:

 Each plaintext letter is represented by the two numbers corresponding to its location on the grid. In the above 6x6 grid, the letter “K” could be written as “25” (across, then down), or “52” (down, then across). The phrase “gay baby jail” could be encrypted as “2111511211125124112326”. 

Alternately, Polybius squares can be constructed with a keyword. Each letter may only be used once. Example: using the key “SWAMP QUEEN”, you would end up with a Polybius square that looks something like this:

Polybius squares are also easy to decrypt. They may be recognized by frequent repetitions of the same digits, none of them higher than 6. 

24 23 52 23 25 34 44 24 24 23 34 41 52 23 54 44 22 22 15
24 23 52 23 25 34 44 24 24 23 43 23 51 54 44 22 34

“Hello. We are looking for highly intelligent individuals. To find them, we have devised a test. There is a message hidden in this image. Find it, and it will lead you on the road to finding us. We look forward to meeting the few that will make it all the way through. Good luck.” That message, signed “3301,” appeared on the underground message board known as 4chan two years ago. It was mysterious, cryptic and sparked a global Internet mystery that has yet to be answered to this day. (via The Internet’s Cicada: A Mystery Without An Answer : NPR)

  • “It’s like a Dan Brown novel if Dan Brown could write this well,” freelance writer Chris Bell tells NPR’s Arun Rath. Bell wrote about the online mystery for The Telegraph. “It’s beyond the realms of my intelligence and beyond the realms of any individual’s intelligence to do this.”
  • Thousands of peopletook on the challenge.
  • To code-breakers who dwell in this world, it was simple in the beginning. The first puzzle used a technique called steganography, concealing a message or image within another image. Hidden inside that first seemingly simple image — those black words on white text — were many more pictures, codes, clues and the reoccurring image of a cicada. That’s what gave the mystery its name: Cicada 3301.

Are we looking at the key to Alexander Hamilton’s secret correspondence? Perhaps. This grille cipher was found among Hamilton’s papers after his death, but the question of if or how the late general ever used it remains unanswered. In the letter, Nathaniel Pendleton, who served as Hamilton’s second in the infamous duel, is asking Evan Jones, whose name appeared on the envelope containing the grille, if he might be able to remember anything about the object’s intended use. 

Grille cipher. The Nathaniel Pendleton Papers, MS 483. New-York Historical Society.

Nathaniel Pendleton. Letter to Evan Jones. November 5, 1808. The Nathaniel Pendleton Papers, MS 483. New-York Historical Society.

Cicada 3301.

Cicada 3301 is perhaps the most mysterious seemingly Internet-based organization in the history of online mysteries. Since 2012, the group has posted numerous puzzles online under that name and has made no reference as to what it does or even where it is from. No one knows who runs it, assuming it really is an organization, or even the name of a single member. Cicada 3301 is able to keep its reputation with so little information strictly because of the interesting scavenger hunt of sorts it has released for three years running.

It all started on January 5, 2012 when a 4chan user posted a steganography clue on the “random” board. The image stated that Cicada 3301 was looking for “intelligent” people. In fact, the word used was “recruiting.” For what, no one has said and Cicada 3301 is certainly keeping it a secret. The image hid a clue that takes some level of specialized knowledge to find. It involved a Caesar cipher, which is pretty standard crypto, but the rest took at least some technical knowledge.

From there, and in future puzzles, clues varied greatly in skill-set necessary for solving and even location. Some of the clues were in physical locations, making it necessary for people who could not reach the clues to use posts on the Internet to get further in the hunt. Moreover, some of the references in the clues are pop culture, literature and other non-tech topics.

Some have touted the Cicada 3301 puzzles as unsolvable. This is not true. Several have solved the hunt and have allegedly received emails from the organization. Still, no one has come forward and stated what they were recruited to do, if anything. Judging by the puzzles, it is possible that Cicada 3301 is simply a cyber group like Anonymous. Of course, there is also the possibility that it is really MI6, the CIA or a similar organization. Information security, cryptography and a number of other skills necessary to crack the puzzles offered by Cicada would be helpful to virtually any large organization, which makes it hard to discover who is behind it. In fact, this would not be the first time an organization used such tactics to recruit new members. We have to assume that Cicada succeeded on that front, as it stated that it found the people it needed after the first puzzle. It began all over again on January 5, 2013 and again on January 5, 2014, so it must be an ongoing recruitment effort.

At this juncture, it is impossible to tell when these recruitment efforts from Cicada 3301 will stop, but that is not stopping people from looking forward to the next year’s puzzles. It may not be a very public honor, but it must be satisfying to know you have reached the end of one of the most famous puzzles in Internet history.

sensual-pluck  asked:

Hey I was wondering how your code of the week thing works? Because I would like to TO and do them but I am new to the code world and need some guidance.

Hello! Here’s a link to a question I answered earlier on that describes the basics of cryptography and provides a few resources to summarize key terms.

As for Code of the Week specifically, people decipher the code than answer it via reblog though I have occassionally received submissions as well - Both work. I’ve also seen people reply back with a message in the same cipher used to create the code to protect their answer from being shared or copied. I appreciate this type of response because it confirms their understanding of the process. 

One of the best ways to improving cryptography understanding is to practice so this blog hopes to provide this opportunity with the challenges having various levels of difficulty. Code of the Week occurs once every week on Wednesday with the answer posted/confirmed during the following days.

Good luck - Hopefully this clarifies a few things!

  • Christopher: Cryptography is the science of codes.
  • Alan: Like secret messages?
  • Christopher: Not secret. That’s the brilliant part. Messages that anyone can see, but no one knows what they mean, unless you have the key.
  • Alan: How is that different from talking?
  • Christopher: Talking?
  • Alan: When people talk to each other they never say what they mean. They say something else. And you’re supposed to just know what they mean. Only, I never do. So how is that different?
  • Christopher: Alan, I have a funny feeling that you’re going to be very good at this.
I ♥ mathematics

Thanks for all the positive feedback and new ideas! This is why I love the Tumblr math community. Based on your suggestions and remarks, some other designs:

  • A heart-filled matrix for linear algebra:

  • Cryptography gets a bitstream encoding a heart:

  • Complex analysis with a heart-shaped contour integral:

  • A logical Boolean circuit:

  • Another cardioid for geometry:

Still to do: number theory, algebra, combinatorics, perhaps trigonometry?

Alan Turing, pioneering British computer scientist who theorized the concept of a general purpose computer in 1936 with the hypothetical Turing machine. During World War II he made groundbreaking developments in cracking the German Enigma codes and designed the Automatic Computing Engine after the war in 1948. In 1952 Turing was prosecuted for homosexuality and died shortly after in 1954 from cyanide poisoning, ruled suicide by an inquest.