Not all information should be available for general viewing. One of the ways to protect information is encryption, that is, the compilation of a special algorithm that allows you to recode information into a form that only some people understand.
The most primitive cipher is the use of auxiliary words or letters. In childhood, many tried to speak in a fictitious language, for example, adding after each vowel the syllable "ma". This method only works during a conversation, others are unlikely to be able to understand you. Written information is unlikely to be encrypted in this way, since such an algorithm is easily calculated.
Another childish cipher is the removal of any letters from a word. Most often, all vowels or every other letter are eliminated. So, for example, from the sentence "Come to visit" you can get "prhd in gst". It is not difficult to decipher without additional hints.
Symmetric ciphers
In another way, they are called symmetric cryptosystems. The peculiarity of this encryption method is that the same key is used for encryption and decryption. The algorithm must be agreed by the parties in advance.
One of the most common methods of such encryption is to write text vertically, not horizontally. A table with a fixed height and variable length is compiled. The required information is recorded vertically. As soon as the text reaches a certain size, it wraps to the next column. Then the table is removed, and the received cipher is sent to the second party. To make a decryption, it is enough to know the height of the table.
If the information is very valuable and needs to be encrypted more carefully, a double permutation can be used. That is, the previous method is repeated again with a change in the height of the table. In addition, in the second table, you can use not columns, but rows, this will only complicate the decryption. Some encrypt records in a zigzag, diagonal, or spiral pattern.
Asymmetric ciphers are called ciphers, the key of which is known in advance. Used primarily on the Internet. For example, digital signatures function with the help of asymmetric cryptosystems.
Replacing letters
The advantage of this encryption method over the previous one is that it is almost impossible to figure it out on your own. At the very least, it will take a very large amount of time.
The easiest way is when one letter is matched against another. For example, A = B, D = D, and so on. First, they write the text itself, and then replace the letters one by one. The advantage of this method is that you can learn the table of necessary substitutions once, and then use it constantly. Your best bet is to simply split the alphabet in half, put the letters side by side, and match them that way.
