Lord777
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Hi, this week we will be talking about cryptography. Let's start with the history and the most ancient methods of encryption, and end with encryption in instant messengers and on websites. Hope you find it interesting. Do not forget to leave your feedback in the comments, as it is you who decide what content will appear on our forum.
What is cryptography? Quite simply, this is the science of encryption and various ways to maintain the confidentiality of information. Even in ancient times, people realized that information is often much more precious than money, which means it needs to be protected. The main purpose of encryption is to make it impossible to extract and use the intercepted information. The first cryptography began to be dealt with in Ancient Egypt, but the most famous cipher, the Caesar Cipher, which everyone probably heard about, was invented in Ancient Rome.
Encryption methods
There are generally two global encryption methods. Symmetrical and asymmetrical. What is the difference between them? Symmetric encryption uses only one universal decryption key, while asymmetric encryption uses two keys - a public and a private. Today we are focusing on the simplest - symmetric encryption, because it was this approach that laid the foundation for protecting the confidentiality of information. Now let's talk about the most famous symmetric ciphers and you yourself will understand everything.
Simple permutation
All ancient symmetric ciphers belonged to one large kind of simple permutation cipher. The bottom line is what. One letter is replaced by some other specific letter, number, or symbol. With the development of cryptography, new methods of symmetric encryption appeared, such as a double permutation, or a magic square, where the same symbols marked different letters, and the encryption itself could be carried out several times. In short, everything is very confusing, so first the basics.
Atbash
One of the oldest methods of encryption. My friends and I used it quite often at school, since the essence of this cipher is very simple. We take the usual Russian alphabet, which consists of 33 letters. According to the atbash method, we replace all the letters of the alphabet back to front - instead of the first - the last letter, instead of the second - the penultimate one, A = Z, B = Y, and so on. So, if we encrypt the word "mom", we get "daddy". Breaking such a cipher will not be difficult, since knowing the principles, it is easier to determine the essence. So let's move on.
Wandering
One of the most ancient encryption methods is Skitala, or the Sparta cipher, which you might have come across in the Assasins Creed: Odyssey game. The skitala was a long rod on which a tape of parchment was wound. The text was applied to the tape along the axis of Skitaly, so that after unwinding the text became unreadable. To restore it, a Skitala of the same diameter was required. A very simple and elegant way to protect the information of its time.
Caesar's cipher
The most famous of the simplest ciphers. The essence of this method is as follows. Each letter of the alphabet is shifted by a certain number of positions. That is, if we take the Russian alphabet and the classic shift by three letters, then the letter A will mean G, B = D, and so on. Thus, the same word "mother" in the Caesar cipher with a shift of three letters will look like this - "PGPG". In this case, the encryption key will be the number 3, which indicates the amount of the shift.
Polybius square
And here is the first cipher with numbers. The ancient Greeks thought of writing their alphabet in a 5x5 square and in parallel signed each row and column with an ordinal number. Thus, they conveyed messages to each other, in which each letter was designated by two numbers - the number of a row and a column. In this case, the 5x5 plate itself acts as the encryption key.
Well, so far it's easy, isn't it? And all because we started from the very basic. Today we have studied what encryption methods are, got acquainted with the most ancient of them, and also understood what an encryption key is. So we are completely ready to disassemble the Enigma cipher machine. Already in the next post. See you!
What is cryptography? Quite simply, this is the science of encryption and various ways to maintain the confidentiality of information. Even in ancient times, people realized that information is often much more precious than money, which means it needs to be protected. The main purpose of encryption is to make it impossible to extract and use the intercepted information. The first cryptography began to be dealt with in Ancient Egypt, but the most famous cipher, the Caesar Cipher, which everyone probably heard about, was invented in Ancient Rome.
Encryption methods
There are generally two global encryption methods. Symmetrical and asymmetrical. What is the difference between them? Symmetric encryption uses only one universal decryption key, while asymmetric encryption uses two keys - a public and a private. Today we are focusing on the simplest - symmetric encryption, because it was this approach that laid the foundation for protecting the confidentiality of information. Now let's talk about the most famous symmetric ciphers and you yourself will understand everything.
Simple permutation
All ancient symmetric ciphers belonged to one large kind of simple permutation cipher. The bottom line is what. One letter is replaced by some other specific letter, number, or symbol. With the development of cryptography, new methods of symmetric encryption appeared, such as a double permutation, or a magic square, where the same symbols marked different letters, and the encryption itself could be carried out several times. In short, everything is very confusing, so first the basics.
Atbash
One of the oldest methods of encryption. My friends and I used it quite often at school, since the essence of this cipher is very simple. We take the usual Russian alphabet, which consists of 33 letters. According to the atbash method, we replace all the letters of the alphabet back to front - instead of the first - the last letter, instead of the second - the penultimate one, A = Z, B = Y, and so on. So, if we encrypt the word "mom", we get "daddy". Breaking such a cipher will not be difficult, since knowing the principles, it is easier to determine the essence. So let's move on.
Wandering
One of the most ancient encryption methods is Skitala, or the Sparta cipher, which you might have come across in the Assasins Creed: Odyssey game. The skitala was a long rod on which a tape of parchment was wound. The text was applied to the tape along the axis of Skitaly, so that after unwinding the text became unreadable. To restore it, a Skitala of the same diameter was required. A very simple and elegant way to protect the information of its time.
Caesar's cipher
The most famous of the simplest ciphers. The essence of this method is as follows. Each letter of the alphabet is shifted by a certain number of positions. That is, if we take the Russian alphabet and the classic shift by three letters, then the letter A will mean G, B = D, and so on. Thus, the same word "mother" in the Caesar cipher with a shift of three letters will look like this - "PGPG". In this case, the encryption key will be the number 3, which indicates the amount of the shift.
Polybius square
And here is the first cipher with numbers. The ancient Greeks thought of writing their alphabet in a 5x5 square and in parallel signed each row and column with an ordinal number. Thus, they conveyed messages to each other, in which each letter was designated by two numbers - the number of a row and a column. In this case, the 5x5 plate itself acts as the encryption key.
Well, so far it's easy, isn't it? And all because we started from the very basic. Today we have studied what encryption methods are, got acquainted with the most ancient of them, and also understood what an encryption key is. So we are completely ready to disassemble the Enigma cipher machine. Already in the next post. See you!
