Cryptography : The word “Cryptography” is derived from Greek words κρυπτόςkryptós meaning “hidden” and γράφωgráfo meaning “to write”. Cryptography is the practice and study of hiding information. It is considered as a branch of both Mathematics and Computer Science.
A Brief History of Cryptography : Probable origin of cryptography : 2000 B.C. In Egypt. (Hieroglyphics).
A Brief History of Cryptography (contd.) : The ancient Chinese art of Cryptography: Ideography. Petroglyph (An Ideograph on rock surface)
A Brief History of Cryptography (contd.) : The ancient art of Cryptography in Mesopotamia, Babylon, Assyria: Cuneiforms and Atbash ciphers.
A Brief History of Cryptography (contd.) : Spartan art of Cryptography : A system which consisted of a thin sheet of papyrus wrapped around a staff.
Messages were written down the length of the staff, and the papyrus was unwrapped. In order to read the message, the papyrus had to be wrapped around a staff of equal diameter.
A Brief History of Cryptography (contd.) : Scytale
Elements of Cryptography: Encryption Decryption Key
Encryption and Decryption The process of disguising a message in such a way as to hide its substance is encryption. An encrypted message is cipher text. The process of turning cipher text back into plaintext is decryption. Plain Text Cipher Text Plain Text Encryption Decryption
Key: A key is a value that works with a cryptographic algorithm to produce a specific cipher text.
Types of Cryptography: Based on the type of key used, Cryptography is broadly categorized into: Symmetric Key Cryptography Asymmetric Key Cryptography