MICROPROCESSOR AND MICROCONTROLLER

Detailed explanation-1: -Cipher disk. Alberti’s cipher disk embodies the first example of polyalphabetic substitution with mixed alphabets and variable period. This device, called Formula, was made up of two concentric disks, attached by a common pin, which could rotate one with respect to the other.

Detailed explanation-2: -In order to decrypt a message written using Alberti’s discs you had to have a matching alphabet on your inner disc. To make matters more complicated the disc could be turned during an encryption so that a different alphabet is used periodically. This was the first instance of the polyalphabetic cipher.

Detailed explanation-3: -1553: Giovan Battista Bellaso envisions the first cypher to use a proper encryption key-an agreed-upon keyword the recipient must know to decode the message. 1854: Charles Wheatstone invents the Playfair Cipher, which encrypts pairs of letters instead of single ones and is, therefore, harder to crack.

Detailed explanation-4: -The first known evidence of the use of cryptography (in some form) was found in an inscription carved around 1900 BC, in the main chamber of the tomb of the nobleman Khnumhotep II, in Egypt. The scribe used some unusual hieroglyphic symbols here and there in place of more ordinary ones.