My Lecture 2 ( Continue....)

Lecture on 27^th July was continued with the last lecture 2 that talked about Authentication & Basic Cryptography. Caesar Ciphers is one of the earliest substitution cipher described by Julius Caesar in the Gallic Wars. For Vigenère Cipher that best known of the manual polyalphabetic cipher uses Vigenère Square to perform encryption. Below is Vigenère Tableau. Mr Zaki also talked about the transposition method of encryption.

There are two types of transposition which are unkeyed single transposition and keyed single transposition. Next, stream ciphers and block ciphers are classification of ciphers. In stream ciphers, they convert one symbol of plaintext immediately into a symbol of ciphertext and it is depends o symbol, key and control information of encipherment algorithm. Besides that, in block ciphers, encrypt a group of plaintext symbols as one block. For example, in columnar transposition, the entire message is translated as one block; block size need not have any particular relationship to the size of the character.

Moreover, Mr Zaki also explained to us about the digital signature. Digital signature for a message from a particular sender is a cryptographic value that depends on message and sender. In slide, Mr Zaki had showed us how to create and verify a digital signature using RSA.

This lecture had mentioned that certification authority (CA) that is to guarantee the authenticity of public keys. The certificate can accompany all senders’ messages and recipient must trust CA and validate the certificate. Before end of this lecture, Mr Zaki had giving us an assignment that needed us to find 1 page of Malay’s newspaper and 1 English’s newspaper. In these newspapers, we have to record all the amount of each alphabet in order to prove the graph in the slide is true.