Chapter I

In the beginning,

there was

4chan

Our story begins on 4chan.org. Ten years ago, it was one of the most popular entertainment resources.
Any visitor could leave a message with a picture and at the same time remain anonymous. There was practically no censorship on 4chan, so often posts and discussions contained a huge amount of pornography, hard trolling and racist jokes.

Here, visitors planned mass flash-mobs and created memes, hacker groups coordinated actions and boasted of success, so a subculture was formed there that opposed itself to social networks which were rapidly losing freedom.
On January 4, 2012, a strange ad appeared on the most popular section of 4chan.
A simple text on a black background challenges viewers to solve a puzzle within the image itself.
Copy of final.jpg from imgur.com
This picture is very different from what usually appears on 4chan and pretty much just issues a challenge. It is not surprising that the forum’s frequent flyers were enthusiastic about finding the solution to this puzzle.

Only one thing can be said about the picture itself — it was made by a person with good taste, familiar with the basics of design and typography.
A well-readable and contrasting font, neat margins on the left and top, the same indentation between paragraphs and double indentation after the signature. The phrases are constructed correctly, without errors and typos.

In general, all this would be more appropriate on the pages of a corporate booklet or textbook, rather than on an entertainment resource.
And I also noticed unusual gaps. Look carefully — the spaces between words differ to the spaces between sentences. Indeed, after a full stop, the author used a double space.

A trifle? Not at all. From such a trifle, I can conclude that the text was written by a pedantic and middle-aged American. Look at this first newspaper printing of the transcription of the Declaration of Independence of America.



It was made in 6 July 1776 — and sentences within paragraphs are separated by double spaces.
In America, this typographic tradition survived until the mid 20th century. At typing courses, secretaries and typists were taught exactly this method of typing.

With the advent of computers, another option came into use — the use of just one space. But traditionalists and supporters of the academic style of text design defiantly continued to use double spaces and even cite studies that prove their correctness.

However, these observations do not bring us closer to the solution of 3301, but only indicate the pedantry and accuracy of the message's author.
ADVANCED TYPING
U.S. NAVY ADVANCED TYPING DUPLICATING AND MANUSCRIPT TYPEWRITER INSTRUCTIONAL
The most obvious options for solving this problem immediately go out the window — neither the name nor the EXIF data contain any information. By the way — 4chan, unlike modern social networks, did not remove this data when publishing — so this shows us that the author himself manually took care of this.
The aspect ratio of the image also attracts attention. It is a square. Or rather, almost a square. 509 points in width and 503 points in height. You have to agree, if you were making a similar picture, you would most likely have chosen rounder values – exactly 500 by 500 for instance. This contrasts with the pedantry that we noted earlier.
The only thing that unites these numbers with the signature 3301 is that they are all prime. They are not divided by any multipliers other than themselves.

This is hardly a coincidence. 3302, 510 or 504 would have changed the whole picture. What does this mean? Nothing yet.

The first 500 prime numbers

The first real hint is hidden in the file itself. Someone guessed to open the image in a regular text editor and look at the source code. Perhaps this person was looking for traces that graphic editors often leave at the beginning of files, but he found something completely different.
See for yourself how .jpg images look like through the eyes of a computer. A hodgepodge of symbols, by which we will not be able to determine what is depicted in the photo — whether it’s a kitten or a picture of an atomic bomb.

But the file from the post on 4chan contained a line intended for human eyes. Look here, at the very end:
TIBERIVS CLAVDIVS CAESAR says "lxxt>33m2mqkyv2gsq3q=w]O2ntk"
It turns out that one message hides another in itself. This technique is called steganography, which combines the word steganós meaning "covered or concealed", and -graphia meaning "writing" This is the most ancient method of secret message exchange. People tried to hide from other people's eyes not the meaning of the letter, but the very fact of its existence.
For example, one of the ancient Greek tyrants conveyed a message to his ally using a tattoo on the body of a slave. The poor guy was shaved bald, and then they tattooed a secret message on the back of his head. After a couple of months, the hair securely hid the message and the slave set off on his way. It was useless to search or interrogate him — he had no letters with him, and he simply did not know the text of the tattoo. The recipient of the message once again shaved the slave and read the message. It consisted of just one word — "Rise up!". Too short? But it was this message that served as the impetus for the beginning of the half-century Greco-Persian Wars.
Steganography does not change the text but hides the very fact of its existence. In our case, unless you open the image in a text editor, you wouldn't even guess that there is additional information in it. The characters at the end of the file do not prevent the display of the image itself — the browser or graphic editor simply ignores them.

This method of transmitting information was also used by the first hackers since it is possible to merge a short note into a photo without additional programs — using simply one command in the console.

Tiberius Claudius Caesar Augustus Germanicus
The fourth Roman emperor, ruling from AD 41 to 54
But we are clearly facing something more complex.

"TIBERIVS CLAVDIVS CAESAR says"


The first three words evoke an association with Ancient Rome. It’s the formal name for Claudius, but what he “says” to us is not yet clear. It looks like some kind of code or cypher. However, if you have ever been even slightly interested in cryptography — the answer is obvious.

One of the first encryption systems was developed by the Roman commander Gaius Julius Caesar.
CAESAR says...
The principle of the encryption is extremely simple — write the alphabet twice on two different sheets of paper, put them one under the other, and then shift the lower one by several letters. And now write down the letters of the message from the upper alphabet, with the letters that were under them.
To decipher the message, the recipient must shift his pair of alphabets in the opposite direction by the same number of letters. This number is called a step. And the algorithm itself is called a shift cipher or Caesar code!

The Caesar cipher has long been a part of popular culture — for example, it can be found on best-selling Dan Brown books about the adventures of Professor Langdon.
In principle, the main drawback of this algorithm is that the key to it is only one number, and even if you do not know it exactly, guessing it will only take a few seconds. Look, it's enough to enter an encrypted message into the online Caesar code calculator and click the step counter.
Try it on cryptii.com
One, two, three, four - and we get a hint!
http>33i2imgur2com3m=s]K2jpg
Looks kinda similar to an internet address, right? The letters http at the beginning, the domain name, com, the jpg file extension. We can assume that the greater-than sign replaces the colon, the number 3 is a slash, and the two is a dot. So we are on the right track, but even with all my assumptions — we won’t get a link.
Why? Because the Romans did not distinguish between uppercase and lowercase letters, they did not use seperate numerical digits, and of course, they didn’t use modern punctuation. The calculator correctly replaced the letters of the alphabet but couldn’t cope with everything else.
We need to expand the alphabet, but in what order should the new numbers and symbols go? If their order does not match the one used by the authors of the encrypted message, we will not be able to get the correct link.

In fact, programmers faced a similar problem at the dawn of the appearance of computers. The letters in computers are stored and processed by their special names or codes. But what code each letter will have was determined by the developers of programming languages.
Until the early 60s, there were several different encodings. But in 1963, the American Standards Association developed a single encoding table — ASCII.

Let's try to supplement our alphabet with letters, numbers and symbols in the order defined by this standard.

ASCII printable characters

Let's try to supplement our alphabet with letters, numbers and symbols in the order defined by this standard.
!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
Try it on cryptii.com
As a result, we get a link to a new hint:
http://i.imgur.com/m9sYK.jpg
By the way, even the shift step would not have to be selected manually. Tiberius Claudius Caesar, who is mentioned in the hint, was the fourth Roman emperor.

However, to find that out, it was necessary to write his name correctly. The author of the riddle replaced all the U with V, concordant with Roman fashion.

I think that this was done so that anyone unfamiliar with this nuance of Latin inscriptions, trying to paste the text into google, would be swiftly cut off.
So, before proceeding to the next hint, let’s discuss. Who is the protagonist in this saga of obfuscation?
Version 1: The Imitation Game
One of the most popular theories, which appeared almost immediately and is very popular today, is that it’s a head-hunting exercise for the secret service. If you’re able to solve the riddles of 3301 before anyone else, you’ll end up at an interview for Men in Black.
This is true, but only partially.
Supporters of this version like to recall the crossword puzzle, with the help of which in 1943, the British special services found gifted people to work on decrypting Enigma.
Indeed, on January 13, 1942, a complex crossword puzzle appeared on the pages of The Daily Telegraph newspaper. According to urban legend, everyone who solved this crossword puzzle received invitations to work in the cryptography department of the great Alan Turing.

In fact, the day before publication, this crossword puzzle was used in a competition that the newspaper held jointly with the "Eccentric Club". Participants were asked to solve a crossword puzzle in just 12 minutes. The editor-in-chief of the newspaper and a representative of the club followed the events.

Out of three dozen applicants, only five could cope with the task. Later, they actually received invitations to work at Bletchley Park as ordinary code breakers.

Alan Turing
Mathematician, computer scientist, logician and cryptanalyst
Please note — the competition was in-person, with observers and an unknown task. And besides, in such an unusual way, they did not recruit analysts, mathematicians or engineers, but ordinary executors — whose tasks included only routine and monotonous work. They were not required to have mathematical abilities or analytical skills — they needed patient, accurate and diligent executors.
By the way, during the war, the staff of the Government Code and Cypher School in Bletchley Park increased from a couple of hundred to nine thousand people. Perhaps some of them could share stories that are a bit more off the beaten track.
Government Code and Cypher School has now changed its name to Government Communications Headquarters and supports that legend. Even now, GCH holds interesting logic contests around Christmas. But they do it absolutely openly, right on their website. Go ahead, maybe you’ll end up as a new recruit.
In the case of the 3301 riddle, I strongly doubt that playing with the simplest steganography and entry-level cryptographic algorithms would help identify really off the wall analysts. Much of what we talked about may be unfamiliar to the general public, but any programmer knows about the Caesar cipher or the ASCII table from the first book he reads. We’re talking ABCs.
Moreover — all versions and keys to solving riddles were discussed right there on 4chan — that is, anonymously and in the public domain.

It's like taking a test in the middle of a noisy square, where everyone is trying to hand over their answers at once.
Now the government services do not have to hide.
The special services during the war really had to act more covertly, so as not to betray the very fact of the existence of cryptographic departments.

That's why if you want to work for the Crown or Uncle Sam — just send your resume to the CIA or MI6’s HR department. Well, if you have already shown your talent as a developer, mathematician or analyst on the Internet — they will contact you anyway if your abilities are needed.
GCHQ sets its 2020 Christmas card challenge
But back to our riddle!
We have a link to an image that has been posted on imgur.com
This is a website where anyone can upload any image. In 2012, more than a million people visited it every day.

Is there a new mystery waiting for us at the end of this link?
Chapter 2. WOOPS!