Quest script for children at home: step-by-step instructions. Playing Spy: A Guide to Encryption Cryptography for Kids
On this day, the Russian Cryptographic Service celebrates its professional holiday.
"Cryptography" from ancient Greek means "secret writing".
How did you hide words before?
A peculiar method of transmitting a secret letter existed during the reign of the dynasty of Egyptian pharaohs:
they chose a slave. They shaved his head bald and painted the message on it with waterproof vegetable paint. When the hair grew back, it was sent to the recipient.
Cipher- this is some kind of text conversion system with a secret (key) to ensure the secrecy of transmitted information.
AiF.ru has made a selection of interesting facts from the history of encryption.
All secret writings have systems
1. Acrostic- a meaningful text (word, phrase or sentence), made up of the initial letters of each line of the poem.
Here, for example, is a riddle poem with the answer in the first letters:
D I am known loosely by my name;
R The rogue and the innocent swear by him,
U I am more than a technician in disasters,
AND Life is sweeter with me and in the best lot.
B I can serve the harmony of pure souls alone,
A between villains - I was not created.
Yuri Neledinsky-Meletsky
Sergei Yesenin, Anna Akhmatova, Valentin Zagoryansky often used acrostics.
2. Litorrhea- a type of encrypted writing used in ancient Russian handwritten literature. It can be simple and wise. A simple one is called gibberish writing, it consists of the following: placing the consonant letters in two rows in the order:
they use upper letters in writing instead of lower ones and vice versa, and the vowels remain unchanged; for example, tokepot = kitten and so on.
Wise litorrhea involves more complex substitution rules.
3. "ROT1"- a code for kids?
You may have used it as a child too. The key to the cipher is very simple: each letter of the alphabet is replaced by the next letter.
A is replaced by B, B is replaced by C, and so on. "ROT1" literally means "rotate forward 1 letter in the alphabet." Phrase "I love borscht" will turn into a secret phrase “Ah myvmya”. This cipher is intended to be fun and easy to understand and decipher even if the key is used in reverse.
4. From rearranging terms...
During World War I, confidential messages were sent using so-called permutation fonts. In them, letters are rearranged using some given rules or keys.
For example, words can be written backwards, so that the phrase “Mom washed the frame” turns into a phrase "amam alym umar". Another permutation key is to rearrange each pair of letters so that the previous message becomes “am am y al ar um”.
It may seem that complex permutation rules can make these ciphers very difficult. However, many encrypted messages can be decrypted using anagrams or modern computer algorithms.
5. Caesar's sliding cipher
It consists of 33 different ciphers, one for each letter of the alphabet (the number of ciphers varies depending on the alphabet of the language used). The person had to know which Julius Caesar cipher to use in order to decipher the message. For example, if the cipher E is used, then A becomes E, B becomes F, C becomes Z, and so on alphabetically. If the Y cipher is used, then A becomes Y, B becomes Z, B becomes A, and so on. This algorithm is the basis for many more complex ciphers, but by itself does not provide reliable protection for the secrecy of messages, since checking 33 different cipher keys will take a relatively short time.
Nobody could. Try it
Encrypted public messages tease us with their intrigue. Some of them still remain unsolved. Here they are:
Kryptos. A sculpture created by artist Jim Sanborn that is located in front of the Central Intelligence Agency headquarters in Langley, Virginia. The sculpture contains four encryptions; the code of the fourth has not yet been cracked. In 2010, it was revealed that characters 64-69 NYPVTT in Part 4 meant the word BERLIN.
Now that you have read the article, you will probably be able to solve three simple ciphers.
Leave your options in the comments to this article. The answer will appear at 13:00 on May 13, 2014.
Answer:
1) Saucer
2) The baby elephant is tired of everything
3) Good weather
Imagine the world around you, in which there is not a single secret, not a single unsolved riddle. How boring it would be! Who loves everything mysterious and secret more than anyone else in the world? Of course, children! Their inquisitive mind strives to explore the unknown, to find the key to all the secrets.
On the other hand, a child, like any other person, has his own secrets: how else could he feel like an individual and preserve his “I” in front of the people around him, including adults. Let's remember ourselves as children: when writing a note to a school friend, did we write it using 33 letters of the alphabet? Most likely not: a special secret alphabet served these purposes. Each group of friends had their own, but, one way or another, it helped keep secret what we didn’t want to tell everyone.
Almost everyone will like this game of “spy” and “detective”. How great it is to imagine yourself as agent 007 or a character in your favorite detective story! In addition, secret writing perfectly develops thinking: after all, transforming some signs into others, incomprehensible, is only half the battle; you also need to be able to quickly read the encrypted messages of your comrades. And this is a real logical puzzle, no less! Its implementation requires concentration, attention and a good sense of rhythm from the young codebreaker.
Isn't that interesting? Please be patient and read this article to the end. In it you will find detailed tips on creating a secret cipher, as well as learn where it can be used, and get acquainted with a brief history of cryptography - the science of encryption.
Where there is a person, there is a secret, or Some interesting facts from the history of encryption
- Everyone has their own secrets, so it would be fair to say: “Where there is a person, there is a secret.” Back in the 2nd millennium BC. in Ancient Egypt there was a writing system called enigma, and by the Greeks in the V-IV centuries. BC. One of the first encryption devices, “Skitala,” was invented. By the way, the Greeks came up with the idea of translating letters into numbers (if only they knew that in the future their idea would turn into the so-called “school cipher”, more about it below).
- In ancient India, secret writing was considered one of the 64 arts that women should master.
- The first book about encryption was published in Arabic in 855 and was called “The Book of Man’s Great Striving to Unravel the Mysteries of Ancient Writing.”
- In Rus' from the XII-XIII centuries. Litorrhea was used - a special alphabetic code, when the vowels in words remained in place, and the consonants changed places.
- Both children and adults are familiar with Arthur Conan Doyle's detective story "The Dancing Men." But few people know that humanoid icons were invented back in the 8th century. Emperor Charlemagne.
- But the writer (and part-time mathematician) Lewis Carroll invented his own method of encryption, and in very unusual circumstances. One cold winter evening (as always), many brilliant thoughts were spinning in his head. But I didn’t want to get out from under the warm blanket to light a candle, so Carroll came up with the idea nycgrapher– a special stencil with which you can write in the dark!
What is a secret code? Instructions for a young detective.
1. Replacing some characters with othersThere are a great many such ciphers. There are even entire cryptographic “libraries” on the World Wide Web, where all these codes are collected, decrypted and conveniently formatted. You can change some letters for others, letters for numbers, real signs for fictitious ones.
A striking example is the above-mentioned “school cipher” - probably the simplest and fastest method of encryption. Its principle is to remember the numbers of letters in the alphabet and replace the letters with numbers, separated by commas. For example, the word "mom" would look like "14, 1, 14, 1." For greater secrecy, the numbers can be shifted - for example, with an interval of +3: the letter A will turn into 4, and M into 17.
An analogue of the “school cipher” can be created by typing on an ordinary computer keyboard: simply replace the Russian letters with the corresponding Latin characters. By the way, this will help improve your typing skills.
This also includes “dancing men” and L. Carroll’s nycgraphy. Come up with your own original code: you can do this not only with your friends and peers, but also with your whole family, and then find encrypted notes in the kitchen in the morning. Great exercise for the mind!
Examples:
alarm clock - 4, 23, 7, 12, 15, 32, 17, 12, 14 (key - letter number +2)
candy - rjyatnf ("keyboard" cipher)
store - nizgagam, toy - akshgrui, shoe - kontiob (try to guess the key to this code yourself!)
2. Half-word
This encryption method was used back in Ancient Rus' to classify secret messages and documents. The half-word signs vaguely resemble real letters, but unfinished. You can do the opposite - add new elements to well-known letters so that they change almost beyond recognition.
3. Inserting extra sounds
In every class there are such “polyglots” who periodically start talking to each other in an incomprehensible language. You listen and listen – and you can’t make out whether it’s English, German or some kind of gibberish! The last assumption is closest to the truth. So-called “gibberish” consists of words in your native language with extra sounds inserted after each syllable. Let’s say we want to pronounce the word “school” so that only our narrow group of friends understands it. There is nothing simpler: we add some syllable to it, for example, “ro”, and instead of “school” we get the mysterious “shkorolaro”. And if you insert “ro” before the syllables, no one will hear the famous word!
By the way, if the previous encryption method is suitable exclusively for written negotiations, then this one is simply ideal for oral ones.
Examples:
gift - pokudakurokku
bookmark - zamekladmekame
University - Uzonizoverzosizotetzo
4. The letter is backwards.
Everything here is extremely simple and clear: we write all the words backwards. Or maybe someone will be able to speak such an encrypted language! In any case, the logic will become simply ironclad.
Examples:
backpack - kazkyur
steam locomotive - zovorap
computer - retweak
informational - yynnoitsamrofni
electricity - yaigreneortkele
5. Creative cryptography.
Who said that letters and words need to be replaced with similar squiggles? After all, a secret alphabet can be created from alternative symbols. There is a 3D pipeline alphabet, where the letters are differently curved pipes. And experimenter John Regsdale recently, in 2006, came up with the Puzzle Code, where the parts of the message are parts of a complex puzzle. If you are okay with your imagination (and this is probably the case), come up with your own unique code and tell everyone about it!
Where can the art of secret writing come in handy?
– For secret correspondence with friends. But in class it’s better not to do this, but to listen to the teacher and remember new information, which will definitely come in handy later!
– For your own notes, which are not intended for prying eyes.
– For a smart and exciting game. This entertainment will go a long way at any party, especially a themed one, where you invite guests to act like great detectives or cool secret agents.
– When going on a long journey, we always stock up on good books and fun games. Why not solve some encrypted story instead of a crossword puzzle? You can do this at speed, together with friends!
– In language lessons – foreign or native. This is an excellent alternative to textbook exercises: deciphering a famous poem or catchphrase will certainly attract interest in the subject being studied and allow you to master spelling in a fun way.
Try yourself in the role of a brilliant cryptographer - and test the capabilities of your mind!
When the complex code is finally solved, it may contain the secrets of world leaders, secret societies and ancient civilizations. Here are the ten most mysterious ciphers in the history of mankind, which have not yet been solved.
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Notes from Ricky McCormick
In June 1999, 72 hours after one person was reported missing, a body was found in a corn field in Missouri. What’s strange is that the corpse decomposed more than it should have in such a time. At the time of his death, 41-year-old Ricky McCormick had two encrypted notes in his pockets. He was unemployed with a high school education, living on welfare, and didn't have a car. McCormick also served time in prison for raping a minor. He was last seen alive five days before his body was found, when he went for a routine check-up at Forest Park Hospital in St. Louis.
Neither the FBI's cryptanalysis unit nor the American Cryptanalytic Association were able to decipher these notes and made them public 12 years after the murder. Investigators believe the mysterious notes were written approximately three days before the murder. McCormick's relatives claim that the murdered man used this technique of encoding messages since childhood, but, unfortunately, none of them knows the key to this code.
Kryptos
This is a sculpture by American artist Jim Sanborn, which is installed in front of the entrance to the CIA headquarters in Langley, Virginia. It contains four complex encrypted messages, three of which have been decrypted. 97 symbols of the last part, known as K4, remain undeciphered to this day.
Deputy head of the CIA in the 1990s, Bill Studman, tasked the NSA with deciphering the inscriptions. A special team was created that was able to solve three of the four messages in 1992, but did not make them public until 2000. The three pieces were also solved in the 1990s by CIA analyst David Stein, who used paper and pencil, and computer scientist Jim Gillogly, who used a computer.
The decrypted messages resemble CIA correspondence, and the sculpture is shaped like paper coming out of a printer during printing.
Voynich manuscript
The Voynich manuscript, created in the 15th century, is one of the most famous mysteries of the Renaissance. The book bears the name of the antiquarian Wilfried Voynich, who bought it in 1912. It contains 240 pages, and some pages are missing. The manuscript is full of biological, astronomical, cosmological and pharmaceutical illustrations. There's even a mysterious fold-out astronomical table. In total, the manuscript contains more than 170 thousand characters that do not comply with any rules. There is no punctuation or breaks in the writing of the encrypted characters, which is unusual for handwritten ciphertext. Who created this manuscript? Researcher? Herbalist? Alchemist? The book once allegedly belonged to the Holy Roman Emperor Rudolf II, who was interested in astrology and alchemy.
Leon Battista Alberti, Italian writer, artist, architect, poet, priest, linguist and philosopher, could not choose just one activity. Today he is known as the father of Western cryptography, and he lived during the same years when the manuscript was created. He created the first polyalphabetic cipher and the first mechanical cipher machine. Maybe the Voynich manuscript is one of the first experiments in cryptography? If the code of the Voynich manuscript is deciphered, it could change our knowledge of the history of science and astronomy.
Shugborough inscription
The Shepherd's Monument is located in picturesque Staffordshire in England. It was erected in the 18th century and is a sculptural interpretation of Nicolas Poussin's painting "The Shepherds of Arcadia", although some details have been changed. Below the painting is a text of 10 letters: the sequence O U O S V A V V between the letters D and M. Above the image of the painting are two stone heads: a smiling bald man and a man with goat horns and pointy ears. According to one version, the man who paid for the monument, George Anson, wrote an acronym for the Latin saying "Optimae Uxoris Optimae Sororis Viduus Amantissimus Vovit Virtutibus", which means "To the best of wives, the best of sisters, the devoted widower dedicates this to your virtues."
Former CIA linguist Keith Massey linked the letters to John 14:6. Other researchers believe that the cipher is associated with Freemasonry. Former Bletchley Park analyst Oliver Lawn has suggested that the code may be a reference to Jesus' family tree, which is unlikely. Richard Kemp, head of the Shugborough estate, initiated a publicity campaign in 2004 that linked the inscription to the location of the Holy Grail.
Linear A
Linear A is a type of Cretan script that contains hundreds of characters and has not yet been deciphered. It was used by several ancient Greek civilizations between 1850 and 1400 BC. After the Achaean invasion of Crete, it was replaced by Linear B, which was deciphered in the 1950s and revealed to be an early form of Greek. Linear A was never deciphered, and the codes for Linear B are not suitable for it. The reading of most signs is known, but the language remains unclear. Mainly its traces were found in Crete, but there were monuments of writing in this language in mainland Greece, Israel, Turkey, and even in Bulgaria.
It is believed that Linear A, which is said to be the predecessor of the Cretan-Minoan script, is exactly what can be seen on the Phaistos Disc, one of the most famous archaeological mysteries. It is a fired clay disk approximately 16 cm in diameter, dating from the second millennium BC. and found in the Phaistos Palace on Crete. It is covered in symbols of unknown origin and meaning.
1000 years after Creto-Minoan, the Eteocretan language appeared, which cannot be classified and may be somehow related to Linear A. It is written in the letters of the Greek alphabet, but it is definitely not Greek.
Dorabella Cipher
The English composer Edward Elgar was also very interested in cryptology. In memory of him, the first encryption machines of the early 20th century were named after his work “Enigma Variations.” Enigma machines were capable of encrypting and decrypting messages. Elgar sent his friend Dora Penny a “note to Dorabella” - that’s what he called his friend, who was twenty years younger than him. He was already happily married to another woman. Maybe he and Penny were having an affair? She never deciphered the code he sent her, and no one else was ever able to do so.
A man from Virginia who creates ciphers containing the secrets of hidden treasure is something out of the realm of Dan Brown, not the real world. In 1865, a pamphlet was published describing the enormous treasure, which today would be worth more than $60 million. It has allegedly been buried in Bedford County for 50 years. Perhaps the man who did it, Thomas J. Bale, never existed. But the brochure indicated that Bale gave a box containing three encrypted messages to a hotel owner, who did nothing with them for decades. Bale was never heard from again.
The only message from Bale that has been deciphered states that the author left a huge amount of gold, silver and jewelry in a stone cellar six feet deep. It also says that another code describes the exact location of the cellar, so there should not be any difficulties in finding it. Some skeptics believe that Bale's treasure is a hoax that was successfully used to sell brochures for 50 cents, which would be $13 in today's money.
A notorious California serial killer known as the Zodiac has taunted San Francisco police with several codes, claiming that some of them will reveal the location of bombs planted throughout the city. He signed letters with a circle and a cross - a symbol representing the Zodiac, the celestial belt of thirteen constellations.
The Zodiac also sent three letters to three different newspapers, each containing a third of the 408-character code. A schoolteacher from Salinas saw the symbols in a local newspaper and cracked the code. The message said: “I like killing people because it's a lot of fun. This is more fun than killing wild animals in the forest because man is the most dangerous animal of all. Killing gives me the most thrill. It's even better than sex. The best thing awaits when I die. I will be born again in paradise, and everyone I killed will become my slaves. I will not tell you my name because you will want to slow or stop the recruitment of slaves for my afterlife."
The Zodiac took responsibility for killing 37 people and was never found. He has imitators all over the world.
In December 1948, the body of a man was found on Somerton Beach in Australia. The identity of the deceased could not be established, and the case is shrouded in mystery to this day. The man could have been killed with an undetectable poison, but even the cause of death is unknown. The Somerton man was wearing a white shirt, tie, brown knitted pullover and taupe jacket. The tags on the clothing were cut off and the wallet was missing. The teeth did not match any existing dental records.
In the unknown person’s pocket they found a piece of paper with the words “tamam shud”, or “finished” in Persian. Later, when publishing material on this topic in one of the newspapers, a typo was made: instead of “Tamam,” the word “Taman” was printed, as a result of which the erroneous name went down in history. It was a fragment of a page from a rare edition of the collection “Rubaiyat” by the 12th century Persian poet Omar Khayyam. The book was found and on the inside cover was written a local phone number and an encrypted message. In addition, a suitcase with things was found in a storage room at a nearby railway station, but this did not help identify the murdered man. Could the Somerton man be a deep-cover Cold War spy? Amateur cryptographer? Years pass, but researchers are no closer to the solution.
This mystery is the newest of all listed, as it was only made public in 2011. The Blitz Ciphers are several pages discovered during World War II. They lay for years in wooden boxes in one of the basements in London, which was opened as a result of German bomb attacks. One soldier took these papers with him, and it turned out that they were full of strange drawings and encrypted words. The documents contain more than 50 unique calligraphic-like characters. It is not possible to date the documents, however, according to the popular version, the blitz ciphers are the work of occultists or masons of the 18th century.
I suspect that cryptography appeared almost simultaneously with writing :-). After all, we write in order to record and transmit information, and we do not always want it to fall into the wrong hands. Officially, the history of cryptography began 4 thousand years ago. The first known use of cryptography is considered to be the use of special hieroglyphs about 4000 years ago in Ancient Egypt. Today, the widest group of highly qualified cryptographers are doctors, I think that many have encountered their mysterious writing :-)
I would like to clarify right away that code and cipher are not synonyms at all. A code is when every word in a message is replaced with a code word, symbol or design, while a cipher is when every letter in a message is replaced with a cipher letter or symbol. In a sense, Chinese characters are also a code.
You can hide a message not only using a cipher or code, but also in more exotic ways. For example, you can tattoo a messenger on the head, and then just wait for the hair to grow (of course, this was used in very old times and, as a rule, slaves were used for this).
The simplest and oldest methods of encryption are replacing the letters of the alphabet with the ones that follow them (the code is called ROT1, which means rotating by one) or rearranging the letters in words. A more complex modification of ROT1 is the Caesar cipher, which is actually two circles with letters rotating relative to each other. Thus, in the Russian language you can create 33 encryption codes using one device. As you can see from the photo, it’s easy to do at home :-)
All of these examples refer to monoalphabetic substitutions, which means that one letter is replaced by another or a symbol. They were used from 3 thousand years BC until the 10th century AD - this is the first period of cryptography. Unfortunately, such codes are easy to solve, since the length of the words does not change. To decipher, you just need to find the shortest words, such as one-letter conjunctions and prepositions, and then you just need to match the letter you see with the most common conjunctions. Having solved one or two letters, you need to substitute them into two-letter ones and so on.
Another way is to count the occurrence of different letters and compare them with the frequency in our language (but this requires additional data, so I prefer the first option) - this approach is called frequency analysis and each language gets its own picture. How often the letters of the Russian and English alphabets are used can be seen in these pictures.
Russian: 
English: 
Of course, there are programs that allow you to do this with an encrypted message in a fraction of seconds, but sometimes it’s nice to work on this task yourself. Actually, during our school years, we had fun by sending each other texts saved in a different MS Word encoding, so that we could decode them later - just for fun.
One of the most famous monoalphabetic ciphers is Morse code, however, it is not used for encoding, but to simplify data transmission. 
The second period of cryptography began in the 11th century in the Middle East and reached Europe only in the 15th century. It is characterized by polyalphabetic ciphers. The essence of polyalphabetic ciphers comes down to the consistent use of monoalphabetic ones. For example, you have 5 monoalphabetic ciphers, the first letter you encode with the first cipher, the second with the second, and so on, when you run out of ciphers you need to start from the beginning. Their biggest advantage is that they do not lend themselves to frequency analysis like monoalphabetic ciphers. The difficulty in decrypting lies in determining the number of mono-alphabetic ciphers; once you know their number, it is enough to select all the letters belonging to one cipher and apply algorithms to decrypt mono-alphabetic ones. Modern computers go through such combinations very quickly, so they are not suitable for hiding very important information.
A classic example of such a cipher is the Vigenère cipher. To create a message, you need to have a table with a set of classic ciphers with an alphabetical shift and a key word: 
Under the text you need to write a key word, repeating it until the number of letters is equal to the number in the text.
Let's assume that the key word is SUMMER, and we want to encrypt the word WELCOME. 
Now, to determine the first letter, you need to find S in the monoalphabetic cipher (row of matrix S), find the letter W (column W), it will be O. 
There is another famous example of a polyalphabetic cipher: the Playfair cipher, which was invented by Charles Wheatstone but is named after Lord Playfair, who introduced it into the British Civil Services. The method is simple, although a little confusing. I’ll try to explain point by point with an example:
For each language, you make a matrix of letters - the point is that the matrix contains all the letters of the alphabet. Therefore, a 5 × 5 matrix is suitable for the English alphabet, and 8 × 4 for the Russian alphabet.
Here is our empty matrix: 
A code phrase or words are used to compose. It is written into the matrix according to a pre-agreed rule: for example, in a spiral (repeating letters are not written). Next, the unused letters of the alphabet are written in order into the empty cells.
For example, we will choose the phrase “It’s summer and we swim every day.” And fill the cells in order: now With l e That And We coupe aems I ka and dy d e no
And we add the remaining letters of the alphabet (BVGZRFHTSSHSHCHEYYA) also in order: 
Our matrix is ready.
We select the phrase that we want to encrypt and divide it into pairs of letters. If an unpaired letter remains, then the selected character is added to it (for the English alphabet this is X, so we’ll stick to this for our example)
Let’s take the phrase “Sunny day” and divide it into pairs: SO-LN-ECH-NY-YD-EN-H
We take the first pair and build a rectangle in our matrix with the corners in these letters, then we replace them with letters in other corners of this rectangle (one corner is replaced with another in the same line). We continue to do this for the remaining couples.
If the letters are on the same line, they are replaced by those adjacent to the right. If the letter is the last one in the line, then take the first one in the next line. For a pair of CO, since they are on the same line, the replacement will be EI. 
For a pair of LN, according to the rectangle rule, we replace it with EG. 
If the pair is in one column, then replace it with letters in the same column, but one lower. Continuing the replacements, we receive a coded message: EI-EG-YA-BM-S-MH-NC
In an extremely simplified representation, the Enigma machine is a set of rotors (each rotor is a mono-alphabetic cipher), adjacent rotors, when connected, complete an electrical circuit. When several rotors were connected in series, a light bulb with an encrypted letter lit up from the formed electrical circuit. With the large use of rotors, there are a lot of options for combining a sequence of monoalphabetic substitutions, which made this cipher extremely effective in those days. Moreover, rotor combinations can change daily, which further complicates the work of cryptographers. The total number of possible combinations was about 2 * 10 145 , for comparison, if I’m not mistaken, there are only about 2 * 10 11 stars in our Milky Way galaxy.
Commercial production of Enigma machines began in the 20s of the last century. The German Navy was the first to use them in data transmission, however, introducing a number of modifications to increase security. Other countries also used them, but usually commercial designs.
Until the 70s of the last century, cryptography, despite constant complications, was still classical encryption with the aim of hiding information from prying eyes. Modern cryptography is more a branch of mathematics and computer science than linguistics. We are now widely applying the results of this new discipline in electronic paperwork and electronic signatures; now this is not only the prerogative of the state, but also part of business and private life. Using encryption methods, it becomes possible, for example, to verify the authenticity of a message or its addressee.
But the work of cryptographers comes down not only to spy games; in my opinion, there is an even more romantic component - the decipherment of ancient and extinct languages. Here, of course, one cannot fail to mention the “Rosetta Stone”. 
It was found at the very end of the 18th century in Egypt, its great scientific value was that it bore 3 identical inscriptions in three languages: two of which were different scripts of the ancient Egyptian language, and one in ancient Greek, which was well known on that moment. Thanks to this tablet, it was possible to begin deciphering ancient Egyptian hieroglyphs. Unfortunately, none of the three inscriptions are complete due to damage to the stone, which I imagine made the work of the cryptographer-linguists more difficult, but also more interesting.
Cryptography even has its own monuments - this is the statue of Kryptos, near the CIA office in the USA. It consists of 4 pages with 4 encrypted messages made by American artist James Sanborn. To date, only 3 out of 4 messages have been deciphered. 
And of course, like any science, cryptography is not without great secrets. 
I have already written about one of them - this, which turned out to be such a tough nut to crack that most scientific cryptographers already agreed that the text was absolutely meaningless, but this year it was perfected, which I also wrote about not so long ago.
Another interesting example of a mysterious book is the Codex Seraphinianus. 
Although, unlike the Voynich Manuscript, it is known that this is the creation of the Italian architect Luigi Serafini, in which he depicts a mysterious world, however, the small text of this codex has not yet been deciphered.
Thus, despite the help of supercomputers capable of calculating the most complex decryption algorithms in a split second, this matter still cannot be done without a creative approach. Cryptography has not yet lost its noble touch of romance.
And, of course, gratitude magnolia1985
for an interesting topic for a post :-)
Man is a social being. We learn to interact with others by observing their reactions to our actions from the first days of life. In any interaction, we use what art historians call “cultural codes.” But cultural codes are the most difficult to decipher; there is no special program that will tell you what a raised eyebrow or seemingly causeless tears can mean; there is no clear answer; Moreover, even the “encoder” himself may not know what he meant by his action! The science of understanding others is something that we comprehend throughout our lives, and the better this skill is developed, the more harmonious, as a rule, is communication with others and any activity that requires coordinated actions.
Studying cryptography in both its forms (encryption and decryption) allows you to learn how to find a connection between an encrypted, confusing, incomprehensible message and the meaning that is hidden in it. Walking the historical path from the Julius Caesar cipher to RSA keys, from the Rosetta Stone to Esperanto, we learn to perceive information in an unfamiliar form, solve riddles, and get used to multivariance. And most importantly, we learn to understand: both different people, unlike us, and the mathematical and linguistic mechanisms that underlie each, absolutely each message.
So, an adventure story about cryptography for children, for everyone who has children, and for everyone who has ever been a child.
Flags flutter in the wind, hot horses neigh, armor rattles: it was the Roman Empire who discovered that there was still someone in the world whom they had not conquered. Under the command of Gaius Julius Caesar there is a huge army that must be quickly and accurately controlled.
Spies are not asleep, enemies are preparing to intercept the emperor's envoys in order to find out all his brilliant plans. Every piece of parchment that falls into the wrong hands is a chance of losing the battle.
But then the messenger is captured, the attacker unfolds the note... and understands nothing! “Probably,” he scratches the back of his head, “it’s in some unknown language...” Rome triumphs, its plans are safe.
What is the Caesar cipher? Its simplest version is when instead of each letter we put the next one in the alphabet: instead of “a” - “b”, instead of “e” - “z”, and instead of “i” - “a”. Then, for example, “I like to play” will become “A mävmä ydsbue.” Let's look at the sign; at the top there will be a letter that we encrypt, and at the bottom there will be a letter with which we replace it.
The alphabet is sort of “shifted” by one letter, right? Therefore, this cipher is also called a “shift cipher” and they say “we use the Caesar cipher with a shift of 10” or “with a shift of 18”. This means that we need to “shift” the lower alphabet not by 1, like ours, but, for example, by 10 - then instead of “a” we will have “th”, and instead of “y” we will have “e”.
Caesar himself used this cipher with a shift of 3, that is, his encryption table looked like this:
More precisely, she would have looked like this if Caesar lived in Russia. In his case, the alphabet was Latin.
Such a cipher is quite easy to crack if you are a professional spy or Sherlock Holmes. But he is still suitable for keeping his little secrets from prying eyes.
You yourself can arrange your own little home plot. Agree on your shift number, and you can leave coded notes on each other's refrigerator for a surprise for someone's birthday, send coded messages, and maybe, if you're separated for a long time, even write secret, coded letters to each other!
But the whole history of cryptography is the history of the struggle between the art of encrypting messages and the art of deciphering them. When a new way to encode a message appears, there are those who try to break this code.
What is "crack the code"? This means coming up with a way to solve it without knowing the key and meaning of the cipher. The Caesar cipher was also once cracked using the so-called “frequency analysis method.” Look at any text - there are many more vowels in it than consonants, and there are much more “o” than, for example, “I”. For each language, you can name the most frequently and rarely used letters. You just need to find which letter is the most in the ciphertext. And most likely it will be an encrypted “o”, “e”, “i” or “a” - the most common letters in Russian words. And as soon as you know what letter is used to denote, for example, “a,” you know how much the encrypted alphabet is “shifted,” which means you can decipher the entire text.
When the whole world learned the solution to Caesar's code, cryptographers had to come up with something more powerful. But, as often happens, people did not invent something completely new, but complicated what already existed. Instead of encrypting all the letters using the same shifted alphabet, several of them began to be used in secret messages. For example, we encrypt the first letter of the alphabet with a shift of 3, the second - with a shift of 5, the third - with a shift of 20, the fourth - again with a shift of 3, the fifth - with a shift of 5, the sixth - with a shift of 20, and so on, in a circle. Such a cipher is called polyalphabetic (that is, multi-alphabetic). Try it, your cipher can only be solved by someone who is privy to the secrets of cryptography!
It would seem that the attackers should have become confused and the secrets should have remained secrets forever. But if the cipher has been cracked once, then any more complex versions of it will also be cracked once.
Let's imagine that someone encrypted a message in two alphabets. The first letter is with a shift of 5, the second is with a shift of 3, the third is again 5, the fourth is again 3 - as on the plate below.
We can divide all encrypted letters into two groups: letters encrypted with a shift of 5 (1, 3, 5, 7, 9, 11, 13, 15, 17, 19) and letters encrypted with a shift of 3 (2, 4, 6 , 8, 10, 12, 14, 16, 18, 20). And within each group, look for which letters we encountered more often than others - just like in the Caesar cipher, only more hassle.
If the coder used three alphabets, then we will divide the letters into three groups, if five, then into five. And then the same frequency analysis comes into play again.
You can ask the question - how did the decryptors know that there were three alphabets, and not, for example, five? They didn't really know. And we looked through all possible options. Therefore, decryption took much longer, but was still possible.
In cryptography, the message to be transmitted is called "plaintext" and the encrypted message is called "ciphertext". And the rule by which the text is encrypted is called the “cipher key”.
The 20th century crept up unnoticed. Humanity is relying more and more on cars: trains are replacing carts, radios are appearing in almost every home, and the first airplanes have already taken flight. And the encryption of secret plans is also eventually transferred to machines.
During World War II, many machines were invented to encrypt messages, but they all relied on the idea that a polyalphabetic cipher could be further obfuscated. To confuse it so much that, although in theory it could be solved, in practice no one will succeed. Confuse as much as a machine can do, but a person cannot. The most famous of these encryption machines is Enigma, used by Germany.
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But while Germany’s most important secret was the design of Enigma, the most important secret of its opponents was that by the middle of the war all countries had already solved Enigma. If this had become known in Germany itself, they would have started to come up with something new, but until the end of the war they believed in the ideality of their encryption machine, and France, England, Poland, Russia read secret German messages like an open book.
The thing is that the Polish scientist Marian Rejewski once thought that since they had invented a machine for encrypting messages, they could also invent a machine for decrypting them, and he called his first sample “Bomb”. Not because of the “explosive” effect, as one might think, but in honor of the delicious, round cake.
Then the mathematician Alan Turing built on its basis a machine that completely deciphered the Enigma code, and which, by the way, can be considered the first progenitor of our modern computers.
The most complex code of the entire Second World War was invented by the Americans. Each US warship was assigned... an Indian. Their language was so incomprehensible and poorly understood, it sounded so strange that the codebreakers did not know how to approach it, and the US Navy fearlessly transmitted information in the language of the Choctaw Indian tribe.
In general, cryptography is not only about how to solve a riddle, but also about how to solve it. People don’t always come up with such riddles on purpose; sometimes history itself throws them up. And one of the main mysteries for cryptographers for a long time was the mystery of the ancient Egyptian language.
Nobody knew what all these hieroglyphs meant. What did the Egyptians mean when they painted birds and scarabs? But one lucky day, the French army discovered the Rosetta Stone in Egypt.
There was an inscription on this stone - the same one, in ancient Greek, Egyptian alphabetic (demotic text) and Egyptian hieroglyphic. Historians of that time knew ancient Greek well, so they quickly learned what was written on the stone. But the main thing is that, knowing the translation, they were able to reveal the secrets of the ancient Egyptian language. The demotic text was deciphered quickly enough, but historians, linguists, mathematicians, and cryptographers puzzled over the hieroglyphs for many years, but in the end they finally figured it out.
And this was a great victory for cryptographers - a victory over time itself, which hoped to hide their history from people.
But among all these solved ciphers, there are three special ones. One is the Diffie–Hellman method. If a small message is encrypted using this method, then in order to decrypt it, you need to take all the computers in the world and keep them busy for many, many years. This is what is used on the Internet today.
The second is quantum encryption. True, it has not yet been completely invented, but if people make quantum computers the way they dream of them, then such a code will know when they are trying to decrypt it.
And the third special cipher is the “book cipher”. Its amazingness is that it is easy for them to encrypt something and not easy for them to decrypt it. Two people choose the same book, and each word in their writing is searched for and replaced with three numbers: the page number, the line number, and the word number in the line. It's very easy to do, right? And it’s not at all easy to solve: how does a spy know which book you chose? And most importantly, computers won’t help much in this matter either. Of course, if you connect a lot of smart people and a lot of powerful computers, such a cipher will not stand.
But there is a main safety rule. There should be so much of this security that the encrypted message is not worth the enormous effort that must be spent on deciphering it. That is, so that the villain - the spy - would have to spend as much effort to unravel your code as he is not willing to spend to find out your message. And this rule works always and everywhere, both in friendly school correspondence and in the world of real spy games.
Cryptography is the art of making and solving riddles. The art of keeping secrets, and the art of revealing them. With cryptography, we learn to understand each other and figure out how to keep something important to ourselves safe. And the better we are at both, the calmer and more active our life can be.
