Caesar Cipher: Caesar Cipher was first used by the ancient Roman military commander Gaius Julius Caesar to transmit encrypted information in the army, so it is called the Caesar cipher.
This is a displacement encryption method. Only 26 (upper and lower case) letters are displacement encrypted. The rules are quite simple and easy to be cracked. The following is a comparison of moving the plaintext alphabet back to 3 digits:
Plaintext alphabet X Y Z A B C D E F G H I J K L M N O P Q R S T U V W
Cipher alphabet A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Then A becomes D, B becomes E, and Z becomes C.
The letters can be moved up to 25 digits (by alphabet). Usually it is moving backwards. If you want to move forward by 1 bit, it is equivalent to moving backward by 25 bits. The displacement is selected as 25 bits.