It is a way of writing a text in such a way that an unauthorized reader cannot understand it. It is mainly used in communication that needs to be kept secret or secured. Even messages on the messenger. There, too, you want to exchange messages with others, but you do not want anyone else to know what is in them.
Because man is a secretive creature, the first attempts at encryption date back to ancient Egypt and Mesopotamia. The first ciphers worked on the principle of cryptographic tables, where it was indicated exactly which letter in the text would be replaced by another letter.
A little later, perhaps the most famous CAESAR’S CIPHER was created, which was also used by Gaius Julius Caesar himself. In its basic form, it works on the principle of shifting each letter by 3 places in the alphabet. For example, we encrypt the letter B as the letter E. When decrypting, we do the opposite, so for example, we decrypt the letter F as the letter C.
Caesar’s cipher
Although Caesar only used a shift of 3, we consider this principle of encryption to be Caesar’s cipher, even with a shift of a different number of letters in the alphabet, which we determine in advance. With the advent of powerful computers, especially in the 20th century, such simple ciphers lost their power and thus their justification.
A sufficiently powerful computer can quickly crack any of these ciphers simply by trying all possible solutions. We call this method a brute force breaking.
Therefore, mathematical encryption based on mathematical operations and relationships came into play.
SENDING A SECRET MESSAGE USING A SYMMETRIC CODE:
- We take the message (plain text)
- We encrypt it using an encryption algorithm and a key
- We send the encrypted message
- The recipient decrypts the encrypted message using the decryption algorithm and the key
- The recipient reads the original message
Key encryption
The most used type of cipher is symmetric cipher. We will need:
- Plain text – the message we want to send
- Encryption algorithm – a sequence of steps or operations that we must perform with open text
- Key – a word, number or something similar that enters the algorithm and thus affects the result
The encryption algorithm tells you what to do with the message.
E.g. „Amplify“ or „add to end“.
The key will tell you what specific number or word to do it with.
E.g. amplify „number 5“ or add „pa“ to the end.
What encryption and decryption algorithm is used in Caesar’s cipher?