welcome back friends, we are discussing the concept of cryptography and its continuation and we are looking on history of cryptography. Classical cryptography is used before computer era.
caser cipher or rotation cipher
Lets takes an example of rotate by 3 , a become d, b become e . “hai” the character will become “kdm” after rotation . receivers should know how to rotate it back.
Cipher disk normally has two concentric disks, each with an alphabet with the periphery, two parties has to agreed with the common character set, for example “s will set d” and the character will be encrypted ,below picture show the cipher disk with we can adjust the character with inner circle “a will set to c” the character will be rotated same like caser cipher.
lot other cryptographic devices are used, during the second world war period also for secure communication. some of the devices used are mentioned below .
- Enigma – used by Germany
- Sigaba – used by united states
- Purble – used by Japanese . after the second world war , common laws are made for having a common encryption and concept also changed in history of encryption.
In the next post we will see the cryptography concept in Computer era.