LECTURE 2 : Basic Cryptograpy

This lecture will cover about the cryptography concept, cryptography algorithms, Monoalphabetic, Polyalpabetic and Transposition

CRYPTOGRAPHY CONCEPT

Basically, cryptography concept is about the idea of a cipher system which is to distinguish information in such a way that its meaning is unintelligible to an unauthorized person..or in Malay..satu system yg digunakan untuk membezakan maklumat yg ingin disampaikan supaya maklumat tersebut tidak boleh dibaca oleh orang yg tidak berkenaan..(lebih kurang cam 2 ler mksudnye..=))

The concept of cryptography or we can say the art of secret writing can be divided into 2 types which are

• Steganography

- hiding messages
- Message does not changed
- Does not involve key

• Cryptography

- scrambling messages
- messages changes
- does involve key


SECURITY TOOLS

The earliest information is encrypt using scytale
On the World War II a machine call enigma machine is used as a mechanical crypto machine.

CRYPTOGRAPHY TERMINOLOGY

• plaintext- original message
• cipher text - coded message
• cipher - algorithm for transforming plaintext to ciphertext
• key - info used in cipherknown only to sender/receiver
• encipher - converting plaintext to ciphertext
• decipher - recovering ciphertext from plaintext
• cryptography - study of encryption principle/method
• cryptanalysis - study of principles/method of deciphering ciphertext without knowing key
• cryptology - field of cryptography + cryptanalysis

CRYPTOGRAPHY ALGORITHMS

Three independent dimension:

• The number of key used

- symmetric or asymmetric??

• The type of operations used for transforming plaintext to ciphertext

- substitution?? or transposition?? or product..

• The way in which the plaintext is processed

- block or stream??

Posted by aziekotani